At the Garden Line, we receive numerous calls from homeowners who want to spray their plants because there is a BUG on them. Before suggesting a pesticide, I always ask the homeowner to describe the insect, because not all insects are harmful. The overly protective homeowner spraying any and all insects may actually be contributing to a buildup of harmful insects. Ladybugs, for example, eat aphids. Destroying the ladybugs will allow the aphid population to increase.
Positive identification of insects is important. Equally important is the identification of the insect at its different life stages. For example, most people are familiar with the adult form of the ladybug, but few recognize this beneficial insect in its larval form. Unfortunately, the larvae looks nothing like the adult and are often sprayed by homeowners who assume they are harmful insects.
What follow is a list and description of some of the most common beneficial insects. Homeowners should take care not to kill any of these insects. If the population of these beneficial insects is high, there is a high population of harmful insects to feed on; with no harmful insects to feed on, the beneficial insects will leave.
DRAGON FLY-Both the adult and nymph form of this insect are active predators on many insects, but are especially predacious on mosquitos. The dragon fly spends much of its life cycle around or in water, which is also the breeding grounds for mosquitos. Many type of dragon flies are common to this area. Adult size may range from 3.8 - 7.6 cm. in length, and color ranges from brown to blue.
LADYBUG-Also called the "lady bird," this insect is more correctly called a "lady beetle." Many different types of lady beetles are found in North America, and almost all are considered extremely valuable predatory insects. As a whole they prey mainly on soft-bodied insects such as aphids, mealy bugs and scale insect, but they also feed on egg masses of many other insects. The soft-bodied, unattractive, black-and-orange spotted larvae of this insect do not resemble the attractive hard-bodied-orange and black spotted parents, but the larvae are ferocious insects with an insatiable appetite for aphids.
GROUND BEETLE-A very large family of insects with over 2500 species in North America. These hard-shelled beetles are mostly black in color but can have an iridescent hue to their shell. They are mostly night feeding insects and not commonly seen during the day, unless found hiding under stones or debris on the soil. As a family they are considered highly beneficial, with both larvae and adult forms feeding on numerous insects, slugs and snails. They are also reported to consume soil maggots, cutworms and other soil borne larvae. Adult ground beetles are approximately 1 cm. in length.
GREEN LACEWING-These beautiful and delicate insects have earned a common name of "aphid lions," because of their enormous appetite for aphids. Both adult and larvae forms also feed on mealy bugs, other small larvae and eggs of many insects and mites. The brown lacewing is more common in the USA, where it is often called the "aphid wolf." Green lacewings are easily recognized by their large, delicate and usually transparent wings, with green and black venation. The fierce-looking mouth parts of the lacewing larvae help to reinforce its common name of aphid lion. Adult lacewings are approximately 1-2 cm. long.
BLISTER BEETLE-This insect can be both beneficial and harmful. The adult form of the Nuttall blister beetle will consume foliage and flowers of plants in the legume family, and therefore can be quite destructive. However, the larvae form of this same insect will also consume large volumes of grasshopper egg masses. The blister beetle is easily recognized by its dark, metallic green or purple shell, giving it an iridescent sheen. These insects are seldom noticed except when the adults swarm in June. The adult form is approximately 2 cm. in length. If blister beetles are found feeding on desirable plants (caragana, honeysuckle, beans, peas), spray the plants with water to discourage the insects. If this fails, resort to a pesticide to protect the plants.
The song birds of summer are a welcome addition to any yard. As well, non-migratory birds help to brighten the day during winter. The shrubs you select and plant during the springtime gardening rush can have a major effect on the bird populations in your yard. Most often birds are drawn to locations with abundant food and adequate cover for nesting or protection. While most shrubs will provide some cover, those that also supply berries as a food source are especially favoured. Here are some ideal landscape shrubs and champion bird charmers.
Dogwood shrubs come in a variety of forms. Leaf colours can range from clear green, through golden-edges to bright silver and white. Most have red or yellow bark that contrasts nicely with wintertime snow cover. The leaves turn bright red in fall. Clusters of white berries that are produced through the summer remain attached to the twigs well into winter.
Cotoneasters are usually grown as a sheared hedge but, they also make excellent accent plants, or can be grown as large, informal unsheared hedges. A naturally-formed cotoneaster maintains more wood which then results in a more abundant fruit supply. Left to grow naturally, cotoneasters may reach two or more meters in height. They produce red or black fruit. The dark green leaves turn various shades of orange and red in the fall. In general, the more direct the sunlight they are being grown in, the redder the leaves will become.
Elderberries make excellent feature plants in the landscape. The golden elderberry is particularly striking. Elderberries can grow to a height of two to three meters and should be left to adopt a natural form. Elderberries are poorly suited to shearing into formal regular shapes, as they have coarse textured twigs that leave a shorn plant with a somewhat porcupine-like appearance. Elderberry fruit are bright red and hang in clusters.
Honeysuckles range in size from one to two meters and produce small bright red, berries at the ends of branch tips. One sure way to tell a honeysuckle, is that the berries are almost always produced in groups of two. The most common honeysuckle problem is aphid attack which results in twisting and curling of the newest growth, making the plants quite unsightly. Honeysuckles have an upright spreading habit and their most important attribute is a brief display of spring flowers.
Anyone who has tried to beat the local bird population to a crop of saskatoons growing on a backyard shrub knows just how much the birds like them, and just how un-ripe the birds are willing to eat them to make sure you don't get them first. Saskatoon shrubs are infrequently used as landscape plants because they can sometimes appear somewhat untidy. Where a naturalized landscape is desired, these shrubs are an excellent choice.
The native chokecherry is also greatly loved by birds, with plants often being completely stripped of fruit before the end of summer. Like saskatoons, chokecherries are better suited to a naturalized landscape because of their untidy appearance and a strong tendency to sucker. The shrubs reach a height of about three meters.
The highbush cranberry is the most common representative of the Viburnum group of plants grown in our area. This plant remains an attractive addition to the landscape all year round. In the spring, large white flower clusters are produced. During the summer, the attractive foliage is a pleasing dark green. The highbush cranberry is one the few shrubs with leaves that turn a crimson red in fall. The bright red berries which maintain a glowing red colour during the winter are favourites of many non- migratory birds. The bushes have a tidy appearance, even at their mature height of two meters, making the highbush cranberry a shrub well worth planting.
Small-fruited Siberian crabapples, and larger-fruited domestic crabapples provide a seasonal display that is attractive to birds. In the spring, there are white or pink blossom; in summer the plants have attractive dark green foliage, with the foliage of some plants becoming red or purple. In fall the leaves become yellow or orange, and in winter, the fruit (especially the yellow fruiting types) forms an attractive display which provides a food source for hungry birds. Because they are grown from seed, crabapples vary in height, and growth characteristic. Unfortunately, crabapples are susceptible to the disease fireblight.
Mountain ash can be considered as a small tree or a very large shrub depending upon whether it is grown with one main trunk, or several smaller trunks. This is another plant with a year-round display. There are white clusters of spring flowers. Late in summer, the dark green compound leaves provide an interesting contrast to the landscape. In fall, the leaves turn brilliant shades of red and orange. The orange berry clusters hang gracefully from the branches through out the winter and are an important food source for cedar waxwings and other birds. The only drawback to mountain ash it that it is even more susceptible to fireblight than most crabapples.
The native buffaloberry is an excellent choice for a naturalized area. Buffaloberries are drought tolerant and are attacked by few pests. A bonus is the tightly clustered bright red berries that cling to the branches. Buffaloberry leaves are a striking silvery-grey colour, which is uncommon in the landscape. The plants reach a height of three meters. Unlike the other plants listed here, buffaloberry plants are entirely male or female. This means that if fruit is desired, you must have both a male and a female plant growing in close proximity. With very young plants it is difficult or impossible to tell the male plant from the female, so you sometimes take a bit of a chance getting several plants that are all the same sex.
Hawthorns, also native shrubs that range in height from two to five meters. The fruit which resembles a very small dry apple remains on the tree well into the winter. The branches are extremely thorny, providing excellent protection for nesting birds. The plant also creates a highly effective living fence which few people or large animals will be willing to violate. Hawthorns are best used in naturalized moist areas.
Like hawthorns, sea-buckthorns have thorny branches, but the thorns of sea-buckthorn are far less aggressive. The most outstanding feature of this large shrub is the mass of bright orange fruit which appear in late summer. Sea-buckthorn branches will literally bend from the weight of thousands of pea sized orange fruit which cling tightly to the stems through much of the winter. Once the leaves have fallen, the showy fruit is visible for long distances. The plants are native to Central Asia, where they survive drought and extreme cold. They also withstand high levels of salt in soil or roadside spray better than most landscape shrubs. Like our native buffalo berry, an entire sea- buckthorn plant will be either male or female, so both a male and a female plant must be present for pollination to occur and fruit to set. Ideally, one male plant should be provided for every four or five female plants, with the male being planted slightly behind the scene, since it will never produce fruit.
When spring is just around the corner, many homeowners have gardening on their minds. The seed catalogues are well worn from repeated flipping of pages. Seeds have been ordered, and some early bedding plants have been started. Many of us are itching to get outside and start seeding the garden, but it is too early. The days are warming but the nights remain too cold to allow seedlings to survive.
One way out of this dilemma is to build your own portable greenhouse. Designed by Agriculture Canada, the greenhouse consists of polyethylene-covered wooden frames that are bolted together and assembled in the garden. The greenhouse can be easily dismantled and folded flat for storage. It can be built to any size specifications, depending on your needs.
The floorless greenhouse allows light and heat to enter, but prevents some of the heat from escaping. Thus, the temperature inside the greenhouse increases during the day. The soil over which the greenhouse is placed stores some of this heat. During the night, when the outside temperature is cold, the heat gradually escapes from the soil but the greenhouse holds enough of this heat to prevent frost from damaging the plants inside.
The system works well if the air temperature is not too cold, though additional frost protection can be achieved by using internal and external curtains.
The greenhouse can be set over the garden area in the early spring (March). For best results, the garden should be located in an area that receives full sunlight. As the air temperature builds up inside, any snow covering will melt and the ground will begin to warm. By mid to late March it is often possible to seed directly into the soil "floor" of the greenhouse. Only plants that tolerate a cool growing season, can be seeded early. Warm-season crops such as require much more warmth that this greenhouse can provide.
As the days become warmer, too much heat may build up inside the greenhouse. It is very important not to let this happen, or you might lose your crop. The simplest solution is to leave the greenhouse door partly open to provide ventilation. When the days become quite hot, remove the greenhouse. In September it can be taken out again and placed over the garden patch to extend the growing season.
Many of our most popular garden flowers produce an abundant supply of seed which can be collected for planting the following season. Also, for those gardeners who wish to try a few of our more showy wildflowers in their garden, seed collection offers an obvious and non-destructive means of acquiring many new and interesting plants.
Timing is a primary consideration in the gathering of seed. In most cases, it is best to allow seed to become almost fully mature before it is collected. Seeds which are collected too early will have a high percentage of immature and inviable individuals. On the other hand, seed that is left too late may be lost when it shatters and disperses naturally from the plant. The maturity level of seed is usually quite easy to detect. As seed heads begin to approach maturity, their moisture level begins to decline, leading to a natural browning. When a certain level of drying has been achieved, seeds begin to fall from the plant. If seed collection is undertaken one or two days prior to its time of natural release, almost all of the seeds will be mature, and collection will be made easy by simply clipping off entire seed heads, and dropping them into paper bags.
Drying is a second essential part of proper seed collection and storage. Dry seed is less subject to attack by various decay organisms such as molds. If moisture levels are high enough to satisfy the needs of the decay organisms, they will almost certainly begin to feed on the seed. In addition, the metabolic processes in a dry seed are greatly slowed. Since a living seed remains viable only as long as its energy supply is maintained, the slower the metabolic rate of any seed, the longer that seed will remain viable. To assure proper drying, newly collected seed heads should left in a dry place at room temperature for a week or more. Partially closed paper bags make ideal containers for drying of newly-collected seeds. Paper bags permit abundant air circulation, but will prevent even the smallest or lightest of seeds from escaping if they should break away from the head during drying. Where large quantities of seed have been collected a small fan blowing over bags of seed will also help to dry the seed more quickly.
Once the seed is fully dry, it can be shaken from the heads or pods, cleaned of chaff, and transferred to air tight containers for long-term storage. The small plastic containers which photographic film is purchased in make excellent air-tight containers for storing small batches of seed. Each container should be labelled with seed type and date of collection. The dried seed can then be moved to a cool dry place for long-term storage. While the inside of most refrigerators offers an ideal storage temperature of around 4°C, the air in most refrigerators is far too humid for suitable seed storage. A refrigerator is therefore only appropriate if air tight containers are being used. A cool corner in the basement is also an ideal spot for seed storage. The low level of humidity found in most homes during winter assures the seed remains dry, and the cool temperatures of the basement will help prolong viability.
Storage life of seed is also highly dependent upon the species of plant. Candytuft and delphinium have a relatively short storage life. Seeds of these flowers will often only remain viable for one year. Bachelor button, sweet pea, strawflower, lobelia, poppy, schizanthus and nicotiana seed will generally remain quite viable for at least two years. Columbine, verbena, hollyhock, shasta daisy, phlox and aster can be counted on to germinate quite reliably after three years storage; while sunflower, pansy, cosmos, marigold, zinnia and nasturtium, stocks and pinks can be stored successfully for up to five years.
Even where ideal storage conditions have been established, it is unlikely that any seed source will provide 100% germination. More often, a germination percentage around 65 to 75% should be expected. It is easy to determine the germination percentage of any seed lot by simply placing 10 seeds between moist paper towels for about 7 days, and then multiplying the number of germinated seeds by 10 to arrive at the germination percentage. If you have a large number of seeds on hand, a more reliable test can be conducted using 100 seeds. Of course, the longer any seed has been stored, the lower the germination percentage which can be expected. It is an especially good idea, therefore, to do a germination test on seed which has been stored for several years.
Another factor which must be considered in the collection of seed from horticultural plants is their genetic parentage. Many of our best known horticultural flowers and vegetables are sold as F1 hybrids. This means that seed for these plants was derived from a carefully controlled cross of two selected parent lines. Controlled pollination assured that a specific set of characteristics would be found in the F1 generation of seedlings. When seed is later collected from these plants, the uniform characteristics the F1 hybrid will often be gone, or greatly altered. Seed collected from F1 hybrids is often non-uniform, less vigorous and lacking most of the desirable characteristics that the parent generation displayed. While it is true that the odd seedling may possess some desirable characteristics, the chances of finding a superior seedling is quite low.
Some plants such as lilies and roses offer the gardener the opportunity to become amateur plant breeders. Because their floral organs are large and easy to work with, these flowers are ideal for people wishing to make a few experimental crosses. By covering selected blossoms with small paper bags, normal wind or insect pollination can be prevented. These blossoms, can then be selectively pollinated with a specific other cultivar of the same species. Usually, each seed from such a cross will produce a plant which is distinctly different from both parents in some way. While the majority of seedings produced from crossing two named cultivars will probably be inferior to the parents, many excellent horticultural cultivars have been found by simply growing out the seedlings of simple crosses, and evaluating them.
You have all heard of the Garden Of Eden - a place where plants grow and flourish all year long. This land is blessed with warm temperatures, ample water and plenty of sunshine. Ah! What a life for a plant. Then there's Saskatchewan. A land characterized by hot, dry summers, cold, dry winters, and plenty of drying winds. It's a tough place for plants to survive, and those that do must conform to the demands of Mother Nature.
One way that plants have adapted to survive here and in other harsh environments is through a process called dormancy. To explain this phenomena, we will follow a tree through a typical year. Early in spring the days begin to lengthen, the sun rises higher in the sky, and the temperatures begin to rise. These environmental factors trigger a change in the driving mechanism in plants. This driving mechanism consists of the supply of plant growth regulators (mostly hormones). The concentration of each growth regulator changes in response to the favorable growing conditions; as a result, plant growth is stimulated.
As spring departs and summer arrives, the trees are growing rapidly, taking advantage of the long days and optimum sunlight. For most trees, growth ceases by late summer (early August). That is, the tree does not produce any more leaves after this time. Again, this is a response to the constantly changing concentrations of plant growth regulators. From now until fall, the objective of the tree is to prepare for winter. During fall the trees are storing up food and energy reserves which are needed for next spring's growth. Forcing new growth occupies the plant and delays the energy-storage process.
The shortening days and the reduction in sunlight cause another change in the driving mechanism, and this stimulates dormancy in the tree. Dormancy is a period of rest and inactivity. The tree is far from dead; it is just awaiting spring. Changing the conditions around the tree may alter the time of year that the tree goes into dormancy. Heavy watering and fertilizing in fall (September) may stimulate the tree to continue growing, and therefore this is not recommended. New growth produced at this time of year will have little chance to prepare itself for winter, and will most likely die from winterkill.
You may argue that watering in fall is recommended to prevent winter desiccation. Agreed, but the timing of the water is important. Late October watering is recommended to prevent winter desiccation. By this time, the tree should be fully dormant and ready for winter. For less tender plants, mulch the soil around their bases to protect the root system from extreme cold, and from fluctuating spring temperatures. If possible, encourage a good snow cover around the plants. Snow is an excellent insulator.
As winter sets in, the tree has become fully dormant, and will not come out of this state until the changing environmental conditions once again stimulate growth. This type of dormancy also applies to seeds of trees grown in this area. Many hardy trees produce seeds which will not germinate in the fall. If the seeds were to germinate in the fall, many of the young tender seedlings would be killed by the severe winter conditions.
The same growth regulators which bring on dormancy in trees also prevent growth of seedlings in the fall. Other types of trees have mechanisms (such as hard seed coats) in the plum and cherry family which prevent immediate germination. When spring arrives, and environmental conditions favor growth, the seedlings burst from the ground and look forward to a year of good growth - weather permitting!
"It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organized creatures."
Some gardeners feel that earthworms are harmful to the soil; in fact, the opposite is true. Earthworms feed on partly decomposed organic material, which they pull down into the soil. In the earthworm, the organic matter is broken down further and after it is excreted (as "castings") it is easily converted by micro-organisms in the soil to nutrients that are taken up by developing plants.
The organic matter that earthworms eat consists of decomposing plant material and animal parts; as well, they eat soil micro-organisms such as bacteria, fungi, and nematodes. Earthworms will feed on roots or other parts of plants that have been decayed by other organisms; but they do not feed on healthy plants.
In many countries, plant material is left on the soil surface for the earthworms as part of recommended agricultural practice. On the prairies, relatively little decomposition of organic matter takes place on the soil surface because of our dry conditions. This is one of the reasons why thatch tends to build up on our lawns. Recycling of organic material is much faster in areas of higher rainfall.
Earthworms are generally found in the top few centimetres of the soil. They must have a moist environment in order to breath, and therefore if the soil dries excessively, the worms will burrow deeper or move to another location. They tolerate a range of temperatures from 0-35C. Earthworms cannot regulate their body temperature and will move to a shady location or deeper in the soil during hot weather. They are basically nocturnal; they come to the soil surface at night when temperatures are lower and humidity higher. Earthworms live in almost all soil types, except very coarse soils (sands) and those that are very acidic.
Reproduction in earthworms is not fully understood. For most types, some mechanism stimulates the worm to produce a cocoon which is deposited into the soil. One or more live worms eventually emerge from the cocoon. They reach sexual maturity in 3-6 weeks. Some species can regenerate amputated body parts but no know species, if cut in two, can generate two viable worms.
In addition to recycling organic matter for plants, earthworms, by their borrowing action and the deposition of castings, modify the soil structure and help to improve such properties as aeration, moisture retention, and water infiltration. Some gardeners complain that because earthworms eat organic matter they cause the soil to harden. It is true that the organic matter is somewhat depleted by earthworms, but earthworm activity reduces, rather than increases, soil compaction. If soil hardening is a problem, it can be easily remedied by adding organic matter. With proper water and composting and with the assistance of earthworms, our garden soils can be maintained in a healthy, productive state.
Fall fertilizing of trees, shrubs and lawns is not recommended in Saskatchewan. In warmer parts of the country, it may be a common practice, but not in the cold prairies. Because fertilizers encourage growth, fall fertilizing may stimulate plants to continue growing when they should be "hardening off" in preparation for winter. Plants that have not hardened off properly will likely suffer from some sort of winter injury.
Seasonal Growth Patterns
In early spring, buds which have been dormant over winter begin to grow in response to warming temperatures and lengthening days. With most trees and shrubs, growth occurs rapidly and continues only until about early or mid-July. At this time growth ceases, and the plants begin to harden off and prepare for the winter. You can check this by examining the tree or shrub. If the leaves at the outer tip are the same size as the leaves lower down on the branch, then you know that growth has ceased. Look carefully and you should also see a bud at the base of each leaf, and a terminal bud at the very tip of the branch.
Some plants, such as raspberries and elderberries, tend not to cease growth in July, but continue growing slowly, sometimes right up to killing frost. When this occurs, the plant has not hardened off properly and, as a result, tip die-back occurs. Any plant that continues growing until late in the fall is susceptible to this form of winter-kill. When fertilizing trees and shrubs, it is best to apply the fertilizer in early spring when the plant is actively growing. By early July, fertilizing should cease.
Lawns are an exception to this; ideally, urban lawns should be fertilized three times a year (May 15, July 1, August 15). Lawns should not be fertilized later than mid-August, for this will encourage growth too late in the fall. Because lawns are low to the ground and usually have a good snow cover, they are more protected from the winter environment and therefore less susceptible to winter-kill that trees and shrubs.
Lawns should be fertilized on approximately May 15 with 2 to 2.5 kg of 27-14-0 or 26-13-0 per 100 m2. Six weeks later apply 2.0 kg of 34-0-0 per 100 m2. Six weeks later apply 2 kg of 34-0-0 per 100 m2.
Trees and shrubs generally do quite well on Saskatchewan soils without the addition of chemical fertilizers. Most problems associated with trees and shrubs are due to lack of proper watering or insect problems and are seldom attributed to lack of nutrition. Excess fertility in the soil promotes excess succulent foliage which is more susceptible to winter injury.
Vegetable and flower beds usually require 11-48-0 or 16-20- 0 applied in spring at the rate of 2 lb per 100 m2.
Do NOT apply fertilizer in late summer or fall. It will cause lush, succulent growth which may not "harden off" in time for winter and therefore be more susceptible to winter kill or fungal or bacterial problems.
Never put granular fertilizer or fresh manure in the planting hole. The chemical salts within the fertilizer may desiccate or "burn" plant roots.
How to Apply Commercial Fertilizer
On lawns, to apply granular fertilizer, first divide the total amount needed in half. With a fertilizer spreader adjusted to the lowest possible setting, walk north-south over the lawn area with half the amount, and then east-west with the other half. This will give an even distribution and reduce the possibility of "burning." If you are hand-broadcasting, follow the same procedure.
In vegetable gardens and annual flower beds, fertilizer may be applied in several ways: (1) fertilizer can be broadcast and thoroughly incorporated into the upper 7 to 8 cm of soil in spring prior to planting; (2) or it can be side-banded that is, incorporated along the sides of each row and about 5 cm deep. This involves more work but is more efficient because less fertilizer is used; or (3) fertilizer can be placed around each plant, 5 cm away and 5 cm deep. This last method is even more "labor intensive" than side- banding but it is also more efficient, in that all of the fertilizer is placed where it can be used by the plants. In perennial borders or other permanent plantings, fertilizer should be incorporated around each plant, 5 cm deep and 5 cm beyond the roots.
Organic vs. Inorganic
There has been much controversy over organic versus inorganic fertilizers. It is important to realize that plants do not recognize the difference between organic and inorganic fertilizers. Their tiny root hairs can absorb only nutrients that have been broken down into inorganic, water-soluble forms. It makes no difference to your tomato plant if the atom of nitrogen it is absorbing has come from a compost pile or a fertilizer factory. There are, however, advantages and disadvantages to each form of fertilizer, organic and inorganic.
Advantages - Organic nutrients include such things as cow, sheep, poultry and horse manure. (One should avoid using pig, dog or cat feces because of the problems involved with internal parasitic worms which may be transferred to humans.) Bonemeal, bloodmeal, compost, and green manures will also provide nutrients for your plants.
There is less danger of over-fertilization by adding decomposed organic material to a garden. It provides a slow release of nutrients as micro-organisms in the soil break the organic material down into an inorganic, water soluble soluble form which the plants can use. The addition of organic material improves soil structure or "workability" immensely. It also vastly improves the water-holding capacities of sandy soils, a distinct advantage in arid climates such as ours.
Disadvantages - For the most part, organic fertilizer is not immediately available to the plants. As noted above, this "slow- release" feature can be an advantage. However, if there is an immediate need for nutrients, organic fertilizer cannot supply them in a hurry. Furthermore, information on the amount of nutrients and the exact elements in an organic fertilizer such as manure is not readily available to the home gardener. In contrast, when you apply manufactured inorganic ferilizer you know the kinds and amounts of the elements it contains, and this allows you to be more precise in meeting a plant's nutritional needs.
The possibility of nitrogen depletion is another drawback of organic fertilizers. Because of complex bacterial action, the addition of a large amount of organic material can cause a temporary nitrogen depletion in the soil and therefore in the plants.
Inorganic Commercial Fertilizer
Advantages - The primary advantage of using packaged commercial fertilizer is that nutrients are immediately available to the plants. As well, the exact amounts of a given element can be calculated and given to plants.
Disadvantages - Commercial fertilizer, especially nitrogen, is easily washed below the level of the plant's root system through the leaching of rain or irrigation. An application which is too heavy or too close to the roots of the plants may cause "burning" (actually a process of desiccation by the chemical salts in the fertilizer). As well, overly heavy applications of commercial fertilizers can build up toxic concentrations of salts in the soil, thus creating chemical imbalances. If organic materials are readily available and cheap, the expense of the commercial fertilizer should also be considered.
Whether a gardener chooses to use organic, inorganic or a combination of both types of fertilizers, it's important to follow the guidelines regarding timing of application, placement of the fertilizer, and the proper amount of fertilizer to be used.
By definition, a fertilizer is "any organic or inorganic material of natural or synthetic origin which is added to a soil to supply elements essential to the growth of plants." (Brady, Soils, 1974)
What exactly does that mean? Organic means something which is or was alive. Animal manures were once living plants. Bonemeal, a by-product of slaughter houses, is composed of ground- up bones of animals. Inorganic means from non-living sources. Rock phosphate, a common source of phosphorus, comes from rocks, a non-living material. The term natural describes the manure, the bonemeal, and the rock phosphate. All are naturally occurring. The term synthetic describes such products as nitrogen fertilizer manufactured by combining natural gas with nitrogen from the air.
Bonemeal, rock phosphate, manure, or manufactured nitrogen fertilizer may be added to soil to supply elements essential to the growth of plants. As long as these elements are supplied in adequate amounts it makes little difference to the plant if they are organic, inorganic, natural or synthetic. Inorganic fertilizer, however, is immediately available to plants, whereas organic fertilizer must be converted by micro-organisms in the soil to an inorganic form before it can be used by the plants.
The Numbers on the Bag
On a fertilizer bag, you will find three or four numbers with hyphens separating them. The numbers indicate, in order, the percentage of nitrogen (N), phosphorus (P), potassium or potash (K), and sulfur (S) - the letters in parentheses are the chemical symbols for the elements. Here are some common fertilizers and the proportion of the elements they contain.
Percentage of N P K S
So, a 25-kg bag of 16-20-0-14 would provide (16/100 X 25 =) 4 kg of nitrogen, (20/100 X 25=) 5 kg of phosphorus, no potash, and (14/100 X 25 =) 3.5 kg of of sulfur. A 25 kg. bag of 34- 0-0 would supply 34/100 X 25 =) 8.5 kg of nitrogen but no other elements. A "complete" fertilizer contains nitrogen, phosphorus, and potash. If one of these three elements is missing, the fertilizer is not "complete."
Beside the major nutrients (N, P, K, S) there are also "micro- nutrients," or trace elements, which are needed by plants in very, very small amounts. But if these are missing, the plants will not be able to complete their life cycle. Among these micro-nutrients are iron, zinc copper, calcium, manganese, and magnesium. Most of these are present in adequate amounts in Saskatchewan soils. Complete house-plant fertilizers usually contain the major nutrients as well as the micro-nutrients. Read the label prior to purchase to ensure this.
Nitrogen is needed for the green, leafy, vegetative growth of plants. When an element is lacking, the plant will show deficiency symptoms. Deficiency symptoms for nitrogen include an overall pale yellow color of the leaves, and plants which are dwarfed or stunted. Nitrogen is mobile in the plant; that is, it moves from the older growth to the newer growth, where it is most needed. Therefore deficiency signs will appear first in older leaves.
Nitrogen moves easily through the soil in the soil water. For this reason it is said to be very "mobile." It is easily "leached" or washed downward by rain or irrigation water. If it is washed below the root zone of the plants, it will not be available for plant use. Therefore,it is the fertilizer element most often lacking and most often needing replacement.
Because of complex bacterial interaction, nitrogen is usually not "available" for plant use until the soil has warmed up in the spring and the soil temperature has reached 15.5C. This is why plants may appear yellow and stunted in early spring when the soil is still cold, even if nitrogen fertilizer has been applied. As soon as the soil warms up, they will appear green and vigorous.
Too much nitrogen or a nitrogen imbalance can delay flowering, fruiting and seed set. The resultant growth is soft and succulent and may be more vulnerable to fungal and bacterial infection. As well, nitrogen can desiccate or "burn" the roots of plants if placed too close to seeds, seedlings or newly planted plants.
Phosphorus is said to promote root growth, root branching, stem growth, flowering, fruiting, seed formation, and maturation. When phosphorus is lacking, stems and foliage often have a red or purplish tinge. This is particularly noticeable on tomatoes and corn. Deficiency signs are seen in new growth first.
Phosphorus is very stable and non-mobile within the soil, so it is not easily leached by soil water. When used moderately, it may be placed fairly close to seeds and seedlings and will not "burn" or desiccate them.
Potash or Potassium
Potassium enables the plant to more readily withstand "stress" such as drought, cold, heat and disease. (In a lawn such "stress" may be in the form of human and pet traffic.) It also stimulates flower color and promotes tuber formation and a strong root system.
When potassium is lacking, leaves appear dry and scorched on the edges and have irregular yellowing. This is seen on older leaves first.
Potassium is usually readily available in Saskatchewan soils and therefore seldom needed as a fertilizer application. But sandy garden soils may show deficiencies. Corn deficient in potassium may be susceptible to fusarium infections.
Sulfur is essential to plant growth and metabolism. It contributes to the unique taste and flavor of cabbage, broccoli, Brussels sprouts, cauliflower, and other members of the mustard family.
Plants that do not have enough sulfur are stunted, thin- stemmed and spindly. The younger leaves are light green or yellow. Fruit and seed maturity may be delayed when sulfur is lacking.
Various forms of sulfur may be added to basic soils to acidify them (or lower the pH).
The frosts that annually conclude our gardening seasons usually arrive either as a radiation or an inversion frost.
A radiation frost is simply a matter of decreasing temperatures near the ground as heat radiates out from the soil to a clear cold night sky. Radiation frosts are seldom a problem on cloudy nights because clouds act as a large blanket, reflecting heat back toward the earth's surface and preventing its loss into space. When we cover our gardens on cold nights we are simply slowing the outward radiation of heat to slow the rate of cooling through the night.
Under normal conditions air is warmest just above the soil surface, and cooler the further it is above the ground. When this normal temperature situation is reversed so that a layer of cool air is trapped below a layer of warmer air, an inversion frost can result.
Everyone knows that cold air is heavier than warm air. Cold air will therefore tend to collect in the lowest areas of any locale. These low areas are known as frost pockets, and should be avoided like the plague when deciding where to locate your garden. If you've ever ridden a bicycle along a country road on a breathlessly calm summer evening you will probably recall having passing through a mass of distinctly cold air. What you were riding through was a frost pocket.
In orchard areas when a very calm cold night threatens to bring an inversion frost, growers will employ wind machines. These powerful fans mix the different layers of air, preventing the coldest air from forming a layer around the plants. In some cases, growers who don't have wind machines may actually charter a helicopter to hover over their fields through the night. The strong downdraft created prevents the pooling of cold air around the plants and avoids a frost. While the services of a helicopter can easily cost many hundreds of dollars for a night, the potential loss of a $30,000 strawberry crop easily justifies the expense.
Throwing Water on a Frosty Myth
An accepted legend among many gardeners is that frozen garden plants can be salvaged if they are sprinkled with water before the sun thaws them in the morning.
It would certainly be nice if this were true. If all a frozen plant needed to be restored to a healthy living condition were to be sprinkled with water during the thawing process, we could all be popping ripe tomatoes into our freezers each summer and thawing them under running water to retrieve fresh firm tomatoes for wintertime sandwiches-but of course we know frozen plants don't work that way.
Obviously running water does not bring frozen plants back to life. The unfortunate truth is that as soon as ice crystals form inside a living plant cell, that cell is fatally damaged. The sharp ice crystals tear apart the cellular membranes, and neither water, science nor all of Humpty Dumpty's men can put them back together.
While applying water cannot undo frost damage, it can prevent it. The key is that the sprinklers must be started before the temperature has dropped to the freezing point, and they remain running at all times when the temperature is below freezing. Shutting off the water for only a couple of minutes when the temperature is below 0°C can permit the plants to freeze.
The method works because the chemical laws of water dictate that a solution containing pure water and ice will always remain at a temperature of 0°C. Ice-water cannot be warmed above 0°C until the last speck of ice has been melted; similarly, ice-water cannot be cooled below 0°C until the last drop of water has been converted to ice. As long as both ice and water are present at the same time, the temperature will hold steadily at 0°C. This means that as long as your sprinkler maintains a film of liquid water over your garden all night, the temperature around the plants will not drop below 0°C. Because all plant cells contain at least a little bit of dissolved sugar, ice will not form in the cells until the temperature drops to at least -1°C. Since it is the formation of ice inside a plant's cells that kills it, plants can actually be coated with ice on the outside, but unharmed by the frosty temperatures.
A word of warning. Sprinklers hitting trees on frosty nights will result in massive ice loads developing on the branches by morning. The ice loads can increase the plant's weight by as much as forty times, resulting in the breakage of large branches. For low-statured plants, the ice load will be supported directly on the ground, and should not be a problem.
Grey mold is a disease that is most common during cool wet weather. It can effect several hundred cultivated and weed species. Gray mold will rot leaves, stems, fruit, flowers sand seedlings. Since gray mold infects such a large number of plants and it is impossible to discuss them all, just a few plants will be discussed. The general symptoms will be similar for most susceptible plants.
In Saskatchewan gray mold commonly effects raspberries, strawberries, roses, tomatoes, beans and lilies and many other fruits flowers and vegetables.
Raspberry fruit can develop a gray fuzzy mat. Canes will develop darkened areas. Fruit can fail to develop or if developed will dry up.
Strawberries also develop a gray fuzzy mat on the fruit. Infected fruit touching non-infected fruit readily spread the disease, as does rain splash. Both green and ripened fruit may be affected.
Rose buds and blossoms fail to develop. Infected buds may droop and stems develop grayish-black lesions. Flowers may turn light brown and shrivel. The gray felt-like mold may develop.
Tomatoes develop gray mold on all above ground plant parts. In the case of tomatoes only cool weather is required as the leaf canopy creates the necessary humid conditions. Newly pollinated flowers are quite susceptible to grey mold infection, and the infection can spread to the fruit. Occasionally gray mold infections on stems will encircle the stem cutting off nutrient flow, causing the top of the tomato plant to die.
Beans develop the typical felty gray coloured mold on leaves, stems and pods. The plants may die and wilt prematurely. The first symptom is usually a discoloured water spot.
Gray mold is the most serious and widespread lily disease. Symptoms include yellowish to reddish brown leaf spots, which in wet weather can grow together leaving the entire leaf blighted. The leaves may also have a oily, drooping appearance. The fungus does not affect the bulb.
An important control measure for gray mold is air circulation. Physical impediments to air circulation can increase the incidence and severity of all fungal diseases, and gray mold is no exception. Things like buildings, fences, hedges and even other plants create an area of stale air. This area may have a higher relative humidity than other areas of the yard. These areas are more prone to fungal diseases. The impediments to air movement can even extend to the leaves themselves. The zone under leaves has a higher humidity than area directly above the leaves.
Densely packed plantings are much more likely to develop gray mold than plants growing in a more open condition. Thick stands of raspberries and strawberries are more likely to develop gray mold than stands that undergo an annual thinning. Lilies should be grown in well drained southern locations. Thin and space bean plants to ensure good air flow. Tomatoes should be well spaced at planting time.
Removing infected leaves, stems, flowers and fruit, is a valuable step in controlling gray mold as it eliminates sites of further infections. Clean up all debris and leaf litter in the fall. The suggested chemical control measures are fungicidal sprays as buds and fruit begin to develop. Suggested possibilities of fungicides are benomyl, zineb, Captan, and wettable sulphur sprayed onto the foliage. It is important to alternate applications of fungicides between those with systemic and non-systemic activity (eg. benomyl and sulphur). Always check the label of the fungicide to ensure that it is registered for your crop, and follow the label instruction regarding application.
Compendium of Bean Diseases. Ed. Robert Hall. American Phytopathological Society. 1991.
Compendium of Raspberry and Blackberry Diseases and Insects. Ed. Michael Ellis, et al. American Phytopathological Society. 1991. Compendium of Rose Diseases. Ed. R. Kenneth Horst. American Phytopathological Society. 1983.
Compendium of Strawberry Diseases. Ed. J. L. Maas. American Phytopathological Society. 1987.
Compendium of Tomato Diseases. Ed. J. B. Jones et al. American Phytopathological Society. 1991.
Diseases & Pests of Ornamental Plants. 5th Ed. Pascal P. Pirone. John Wiley & Sons. 1978.
Although we tend to think of soil as a rather solid substance, it's actually composed of liquid and air spaces as well as solid materials. The solids make up about 50% of the soil by volume. Most of this is rock material which has been broken down by the action of heat, water and wind into particles of various sizes.
A smal portion of the solid materials (about 2 to 10%) is made up of organic material which is or was alive. While most of this consists of decayed vegetation, the organic portion of the soil also consists of micro-organisms such as bacteria and fungi, earthworms, insects, and the occasional small animal.
In between the small solid particles are air, or "pore" spaces At favorable moisture levels, half of the total pore space will contain air and the rest water. After irrigation or rain, when the soil is saturated with water, there may be little or no air in the pore space. If drainage is poor, this condition will continue, depriving the plant roots in the soil of oxygen and therby harming the plants. This explains why adequate drainage is essential to good plant growth.
Poor drainage is indicated by a mottled grey soil color, constantly wet soil, or water "sitting" on the soil surface for a long time after rain or irrigation.
To improve drainage, ditches may be dug to drain away the excess moisture. Raised beds can also be constructed. These may be 30 to 60 cm high and consist of top soil with perhaps soil amendments. Alternatively, raisled beds may be built with sides of wood, stone, concrete blocks, or old railway ties (from which the preservative chemicals have been leached). Raised beds have good drainage and warm up quickly in the spring. Sub-surface ceramic drainage tiles, once widely recommended to improve drainage, are now usually considered prohibitively expensive.
Making the Grade
During construction, excavating or landscaping, the grade or slope of the soil surface may be changed. If only a few feet of extra soil is added to the surface, trees can be adversely affected or even killed. The added soil interferes with the exchange of gases, particularly oxygen, between the roots of trees and the air above the soil surface. Protect older established trees when carrying out a major grade change. The construction of large "wells" which coincide with the drip line (the furthest extent of the branches) will maintain the existing grade around these trees and assure the continuation of a gas exchange between the roots of the trees and the atmosphere above the soil surface. Similarly, if soil is to be removed, retain the soil around existing trees through the use of a retaining wall extending to the drip line.
I. The Function of Water in Plants
Since water is central in the discussion of drought and plants, a basic understanding of the functions water plays in the lives of plants is important.
All chemical reactions that occur in plants take place in solutions composed mainly of water. Photosynthesis depends upon water. Similarly, nutrient transport is reliant upon water. Soil nutrients are brought to the root in a solution of water; they enter the root dissolved in water and are carried through the plant in sap composed largely of water.
Plant growth depends upon water. In fact, it is water pressure on the inside of cells which causes cell walls to stretch, and cells to grow. As each of the many thousands of cells forming a plant enlarges slightly, we see the effect as overall plant growth. A plant that does not have enough water pressing against its cell walls appears wilted. In this case, water acts in much the same way as air in a balloon. With abundant air, the walls of the balloon are stretched. When air is reduced, the walls become limp. Water therefore not only enables plants to grow, it allows them to stand upright.
II. Water Movement Through the Plant.
It is well known that water enters a plant through the roots. Less well known is the fact that 99% of the water that enters through the roots exits soon afterward as vapour from the leaves. During the day, water is almost always evaporating out of leaves into the surrounding air. This process is called transpiration. During transpiration, water vapour passes out of leaves through tiny holes called stomates. On a hot, dry, windy day, water loss to transpiration can be quite high, requiring relatively large amounts of soil moisture to prevent wilting.
A major function of transpiration is cooling the plant. The process of water evaporating from inside of the leaf out into the surrounding air removes heat from the plant. This cooling is similar to what a swimmer feels after emerging from a pool. A summer breeze feels far cooler on wet skin than on dry, because evaporation of water from the skin (liquid changing to vapour) removes large quantities of heat. Under hot conditions, plants rely heavily upon this means of "evaporative cooling". The effectiveness of this method is obvious when you consider the temperature difference between a lawn and an adjacent sidewalk on a sunny day.
Transpiration plays a second major role in plants besides cooling. It is transpiration that pulls water to the tops of all plants - even the very tallest of trees. Between the roots and leaves of a plant, water is drawn through many thousands of cells called xylem vessels. Xylem cells can be thought of as bottomless barrels stacked end to end to form long narrow pipelines running from the roots to the leaves. If we think of water molecules in this xylem pipeline being like links in a chain, each time one link (or water molecule) evaporates from the leaf at the top of the pipeline, it pulls the chain upward exactly one link behind it. Because of water's strong tendency to hold together in drops, it takes less energy to pull the entire chain upward one link than it would take to break the chain. The chain of water molecules therefore remains intact and continues to pull slowly upward. This is how transpiration pulls water to the tops of plants. In order to get water to the leaves, the plant must lose water through evaporation.
If at any time the soil cannot supply enough water to maintain the chain, special balloon-like cells around the stomates called "guard cells" will fill with water, swell and block the stomates - effectively sealing the top of the system and stopping water loss. Because stomate closure also halts important metabolic processes in the plant, the plant will keep them open as much as possible. During the day, whenever adequate water is available, stomates are kept open. Because they are the openings through which carbon dioxide gas enters the leaves, stomates must be open for photosynthesis to take place. Carbon dioxide is an essential raw material for photosynthesis. When its supply is shut off, photosynthesis must stop. A plant under water stress will therefore close its stomates and stop photosynthesis. Since photosynthesis is the primary means by which plants generate their food supply, frequent stoppages can lead to an overall decrease in growth of the plant. This is one of the main reasons a plant growing in a drought-prone area will be smaller than the same type of plant growing where there is abundant water.
III. Water and the Root
Free water moving through the membrane of a cell always moves from an area of higher water purity to an area of lower water purity. Because water in a plant always contains sugars, salts and other dissolved substances, the water in soil is usually more pure than the water in a plant. Relatively pure water from the soil therefore moves into the less pure water of the root by diffusing through the thin walled root cells.
To assure that the water in the root remains less pure than the water in the soil, the plant will often load salts into the sap of the root. Potassium salts are especially important to plants for this reason. By maintaining a relatively high level of potassium salts in roots, water is always able to diffuse from the soil into the root. This is why many plants are unable to live on saline soils. Water in salty soil is so highly concentrated with salts that the "more pure" water of the root flows out into the "less pure" water of the soil.
The youngest roots of a plant absorb the greatest amount of water. Many thin walled root hairs near the ends of young roots allow easy passage of water from the soil into the root. Because the majority of feeder roots are located at the outer ends of roots, trees are correctly watered at, or beyond the drip line. Water applied at the trunk is generally not available to the tree.
I. Environmental Factors Influencing Water Use
The number of environmental factors playing a role in water uptake by plants is very great. Only a few will be discussed here. If we remember that 99% of the water taken up by a plant is lost through evaporation of water from small holes in the leaves called stomates, the losses can be more easily understood. Water loss from a plant is almost all due to evaporation. Like wet laundry hung on a clothesline, factors in the environment will speed or slow the rate of drying that occurs.
Shade can greatly reduce the water needs of a plant by lowering the surrounding air temperature. The shaded side of a tree loses 25% less water than the sunny side. A forest tree shaded by many neighbouring trees loses considerably less water than a lone tree standing in full sun and exposed to wind. Of course, while the forest tree may lose less water, its roots have to compete with neighbouring trees for available soil moisture to replenish the lost water.
Humidity affects water use. The humidity of air in a city where there are large areas of concrete is significantly lower than the humidity over turfgrass or other living plants. In dry air, water evaporates more easily, and plants dry more quickly. Plants increase the humidity in their immediate environment by releasing water to the air by transpiration. In a dense canopy, water lost through transpiration will humidify the air surrounding the leaves, and slow the rate of water loss from other leaves.
Wind greatly increases the rate of evaporation from leaves. Like laundry on a clothesline, plants in wind dry much faster than plants in calm air. Shelterbelts are therefore very effective in reducing water consumption of plants by reducing the amount of wind.
Temperature has dramatic effects on increasing water loss from plants. Obviously, a plant will lose water more quickly on a hot day. Water uptake is also slowed by low temperature. Evergreens often show dieback due to spring drying. On a hot, spring day the top of the plant may become very warm, while the roots are locked in cold soil, unable to replenish water as quickly as it is lost.
II. Plant Adaptations for Reduced Water Use.
In nature, most plants avoid drought by growing only where there is adequate moisture to sustain their needs. Marsh species are not found on uplands, and upland species are not found in deserts. Within their range of adaptability, most plants avoid drought stress by either conserving available water, or by enhancing their up-take of limited soil moisture.
Water conservation can involve careful regulation of guard cells: the cells which open and close to permit transpiration in the leaf. Because 99% of the water leaving a plant is lost through the stomates, rapid closure of stomates at the first sign of drought is an effective means of conserving moisture when water supply is low. One of the reasons green ash is more drought tolerant than trembling aspen is because the ash tree closes its stomates more quickly in response to dry soil, resulting in less water wastage during periods of drought.
Other features to enhance water conservation include development of small thick leaves with a thick waxy covering. Plants with small thick leaves lose water more slowly than plants with large thin leaves. Smaller leaves provide less surface area from which water can evaporate.
Small hairs on a leaf surface are also effective in reflecting light to shade the leaf and reduce air movement directly over the leaf surface. Silvery leaved plants are often utilizing this method or water conservation.
Succulents have adapted to survive conditions of extreme water stress. They do this by storing water in thick fleshy leaves, and by opening stomates for entry of carbon dioxide only during the cool of night. A modification of normal photosynthesis permits these plants to take in and store carbon dioxide at night for use in photosynthesis the following day.
A major factor determining the amount of water absorbed by a plant is the depth and concentration of its root system. Deep tap roots in combination with shallow surface roots permit plants to capture moisture from light rains, as well as water from lower in the soil profile. Scot's pine is considered drought tolerant because of this type of root system.
Turfgrasses often form very dense mats of roots through which little water is able to pass. By developing highly fibrous root systems, these collect a large amount of soil moisture before it can penetrate to more deeply rooted species.
VI. Cultural Practices to Reduce Water Use.
The first step in reducing water use for trees and shrubs is wise choice of plant material. Nature should always be your guide. Choose those plants which would be found naturally in the same environment as your garden. A birch tree from a cool moist river valley will almost certainly decline and die on an arid site without considerable supplemental water. A drought tolerant green ash from further up the slope of the same river valley will survive much more successful in a dry garden.
When watering, always water deeply and thoroughly. Roots will only grow where soil is moist. They will not extend into dry soil. Frequent shallow watering confines roots to the upper regions of the soil, leaving plants shallow-rooted and prone to rapid drying between waterings.
Since most of the "feeder" roots which absorb water are located at the furthest extent of the root system, it is pointless to water at the trunk of a tree. Water at the "drip line" and beyond where active roots will take up the water.
Mulches will moderate soil temperature and enhance soil moisture retention. However, not all mulches are equally as effective. An effective mulch should be made of organic materials. Decomposition rate, water absorption capacity and volume weights may make some materials more effective in water conservation than others.
Enhanced root growth is important. An increased level of phosphorous will stimulate healthy root growth.
Competition from aggressive shallowly rooted plants with fibrous root systems will effectively reduce water availability to other plants. Turfgrass, ground covers and herbaceous weeds are particularly competitive, and will rob valuable moisture from deeper rooted trees.
Concrete, pavement and large buildings not only increase air temperature but limit water availability and focus the wind, often greatly increasing it. Trees and shrubs in highly urbanized settings will lose more water than trees in natural parklike settings.
DROUGHT-TOLERANT TREES AND SHRUBS
An essential starting point in establishing a drought-tolerant landscape is proper plant selection. Correct plant choice can greatly reduce the demand for supplementary water, fertilizer and other garden inputs.
In general, the better suited a plant is to its environment, the less additional attention it will require. Trees and shrubs native to any particular area are obviously well adapted to local conditions of moisture, sun, wind and soil. Prairie plants have survived here for thousands of years without human assistance, and can therefore be expected to thrive in a garden established on what is essentially their home turf. Many drought-tolerant plants have also been introduced from other parts of the world. While exotic plants certainly make excellent additions to the landscape, there is no reason for gardeners to believe that every plant introduced from afar is somehow superior to those found close at hand. Although the word "exotic" often carries connotations of romance and wonder, the word simply means, "introduced from abroad." To help remove some of the romance from the word exotic, just remember that caragana is an exotic shrub; it was brought here from Siberia.
A number of drought-tolerant evergreens are well suited to a xeriscape garden. Colorado spruce (Picea pungens) is not native to the Prairies, but is fully hardy and very drought- tolerant. These characteristics combined with its excellent pyramidal form make it one of the most highly prized landscape conifers on the Prairies. A number of superior cultivars exist. Cultivars are propagated by grafting to maintain the desired form and colour. Colorado spruce seedlings will show an array of colours from green to blue.
Pines suitable to dry conditions include Scots pine, lodgepole and mugo pine. Of these, only lodgepole (Pinus contorta var. latifolia) is native to the Prairies. This is the forest tree of Cypress Hills. Its survival in south-west Saskatchewan is evidence of its suitability in low moisture landscapes. Scots pine (Pinus sylvestris) and mugo pine (Pinus mugo) are both native to Europe, but very well adapted to conditions on the Prairies. Scots pine will form a very attractive tree on soils that are too sandy for most other species, and the exposed orange bark of mature specimens makes a striking addition to both the summer and winter landscape.
Mugo pine is most often seen as a shrub. If permitted to grow without pruning, it may reach the size of a small tree, usually nearly as wide as it is tall. If new growth is removed each spring, this pine can be maintained as a dense, drought-tolerant shrub.
Like many of our toughest trees, Siberian larch (Larix siberica) arrived here from Siberia. Perhaps no other region of the world more strongly conveys the notion of a dry, cold, windswept landscape. This "evergreen" is closely related to our native tamarack, but somewhat better adapted to dry conditions. Like all larch species, it develops striking gold colour in fall before dropping its needles. Soft new foliage is produced each spring.
Junipers are among the most drought-tolerant of evergreens. Creeping, or low juniper (Juniperus horizontalis) frequently inhabits arid sandy sites where few other woody plants survive. There are many horticultural selections, with heights ranging from true ground hugging forms to some reaching 30 cm in height. The range of colours extends from deep green to bright blue. While most will survive in partial shade, full sun is preferred, and is essential for blue selections to achieve full colour. These plants make superb ground covers on most arid sites.
Common juniper (Juniperus communis) is often found growing naturally on the Prairies adjacent to horizontal juniper, in pockets where slightly more protection is offered. It forms a low evergreen shrub about half a metre tall. The leaves are awl- shaped and very sharp. The cultivar `Depressa Aurea' develops clear golden yellow foliage when grown in full sun, and is much less prone to winter die-back than the more common Golden Pfitzer juniper (Juniperus x media `Pfitzerana Aurea').
Savin juniper (Juniperus sabina) is a European native that is well adapted to prairie conditions. It is typically vase- shaped, with a somewhat feathery growth habit. Cultivars range in height from 30 cm to 1 metres, and all form good ground covers or low evergreen shrubs under even to low moisture conditions.
Rocky Mountain Juniper (Juniperus scopulorum) is our only upright juniper. It forms a broad loose pyramid sometimes reaching 5 metres in height. Although similar in form to cedars, Rocky Mountain juniper is much more rugged, requires less water and will generally not suffer from winter drying. As with other junipers, numerous cultivars are available, with most being silver to grey-blue in colour.
Manitoba maple, green ash and bur oak are all native trees, well suited to xeriscape conditions. Of the three, green ash (Fraxinus pensylvanica subintegerrima) is the most drought tolerant. It can be found growing native in the arid upper slopes of many river valleys throughout the Prairies. It has a deep tap root and bright yellow fall colour. A common objection to the tree is its slow spring leaf development and rapid leaf- drop in fall. `Patmore' is a selection which holds its foliage longer than others green ash selections.
Like green ash, Manitoba maple (Acer negundo) is also native to river valleys throughout the prairie region. It is normally found lower in the valley, however, where the moisture supply is more dependable. Although this tree was once extensively planted for shade and shelter, it has fallen out of favour with most gardeners. The trees tend to drop large numbers of seeds producing many weedy seedings. It is also highly attractive to aphids, resulting in a nearly constant shower of sticky honey-dew on all surfaces beneath the tree. The trees are highly susceptible to damage from trace amounts of 2,4-D, with most specimens showing damage due to chemical drift by mid- summer.
If Manitoba maple has fallen out of favour, bur oak (Quercus marcrocarpa) has been the tree picking up the slack. This long-lived stately tree is fully adapted to our environment. Once established, it is drought tolerant with a deep tap root. The tree is native to southern Manitoba and south-eastern Saskatchewan, and was certainly under utilized in the past.
Russian olive (Elaeagnus angustifolia) is the European "cousin" to our native wolf willow (Elaeagnus commutata). Like wolf willow, all young portions of Russian olive are entirely covered in silvery scales, giving the tree a distinctly silver appearance. Unlike the North American native, Russian olive grows to form a tree of 8 metres in height. It is well suited to dry or saline conditions, with its silvery foliage providing excellent contrast in the landscape. When produced, the silvery olives provide winter food for birds.
An array of drought-tolerant shrubs are native to the Prairie region and well-suited to the xeriscape garden.
Saskatoon berry (Amelanchier alnifolia) is a very common shrub across most of the Prairies. A great deal of variation is found in the species, but generally it forms an upright spreading shrub. White blossoms in spring are followed by clusters of purple-blue berries in July. The fruit is highly prized as a flavour of summer on the Prairies. If the plant is to be grown for fruit, it is best to plant enough bushes to satisfy the local robin population. Where only one or two bushes are planted, birds often devour most of the fruit before it is ripe.
Potentilla or cinquefoil (Potentilla fruticosa) is a drought-tolerant low shrub about 1 metre tall that flowers with white to yellow blossoms from June to freeze-up. The plants have few insect or disease problems, and will form a very dense un- sheared low hedge. They also serve as foundation planting, or low shrub beds where they receive full sun. Potentilla does not adapt well to shade. The shrubs also tend to hold many dead leaves and flowers through the winter, giving them a somewhat untidy appearance.
Silver buffaloberry (Shepherdia argentea) can be used either as a large shrub or small tree, depending on whether it is pruned to a single or multiple trunk. It is native to open prairie, has a rugged appearance, stout thorns at the end of each branch, and will produce abundant bright red berries if both male and female plants are planted in close proximity. The fruit can be used for wine or jelly. If berries are left on the plant they are highly attractive to birds in winter.
Similar to buffaloberry, but with finer texture, sea-buckthorn (Hippophae rhamnoides) is another arrival from Siberia. This plant can also serve the function of large shrub or small tree. The bright orange berries of this plant may be produced in abundance where male and female plants are growing in close proximity. They too are highly attractive to birds. Caragana (Caragana arborescens), yet another escapee from Siberia, has long been known as the shelterbelt plant that would survive anywhere. While common caragana has little to recommend it, a variety of naturally occurring mutations in the species have produced a host of unusual forms more visually pleasing, but still as tough as the original. `Sutherland' caragana is very similar to common caragana, except for a columnar growth habit. Where a columnar form is desired on a hot dry site, `Sutherland' caragana would be hard to beat. `Lobergii' caragana takes on the feathery appearance of asparagus tops because of a leaf mutation causing fern-like foliage. Weeping caragana `Pendula' has similar leaves and flowers to the original, but all branches grow dramatically downward. Although this plant is most often seen grafted on a standard of `Sutherland' caragana, if grown on its own roots it functions as a tough sprawling ground cover, will cascade down a steep slope, or overhang a retaining wall forming an attractive display. `Walker' caragana combines the fine leaves of `Lobergii' with the downward growth of `Pendula' to form a finer-textured ground cover or cascading type caragana. It too is available grafted to a standard, but is probably much more functional growing on its own roots.
People have used plant aromas for centuries. Early Egyptians carried hand bouquets and burned aromatic plants in their homes, or scattered pleasant-smelling plants on their floors. Pious Pharisees of biblical days decorated temples with mint to "make a sweet smell before the Lord." Our climate does not allow us to have fresh plants year-round, but we can still have their aromas by making potpourris.
A potpourri is a mixture of dried, sweet-scented plant parts including flowers, leaves, seeds, stems and roots. Many plants that are used in potpourris can be grow here. So, selecting flower seeds or bedding plants for next year's garden, consider the ornamental value of the plants as well as the aromatic value. If possible, locate aromatic plants near a deck or patio where they can be fully appreciated, and plant more than you usually would so that some can be harvested for a potpourri.
The basis of a potpourri is the aromatic oils found within the plant. These oils are not confined to the flowers, but they are at their peak at flowering time, so harvest leaves and flowers just as the plant begins to flower. Harvesting in the morning, after the dew has dried, is recommended.
After harvesting, dry the plant parts in a warm, airy, dry room either by hanging away from direct sunlight (hand drying), or by placing a single layer of plant parts on a plastic rack (flat drying). Do not crowd the leaves and flowers, for they need room to dry thoroughly to avoid mildew that can destroy the potpourri. Natural air drying at a rapid pace is best. Drying at hight temperature may result in loss of the aromatic oils.
Two kinds of potpourri can be made ‹ dry and moist. The most common, the dry method, is quicker and easier, but the potpourri does not last as long. Both methods require a "fixative," which is responsible for absorbing the aromatic oils and slowly releasing them. Common fixatives include finely ground non-iodized (pickling) salt, orris root (dried rhizomes of iris plant), sweet flag (calamus root), gum benzoin, storax (styax) and ambergris. These are available at local drugstores, hobby stores and herbal stores. Make sure the fixatives are finely ground so they can better absorb the aromatic oils.
A number of books at local bookstores and libraries clearly and concisely describe how to make a potpourri. I recommend you obtain one of these books and follow the instructions given. For making dry potpourri, most books advise using an equal weight of finely ground spices (such as cinnamon, cloves and nutmeg) and fixative. Two different fixatives are often used in case one is more effective that the other. Most books also recommend adding a few drops of essential oil (available at hobby stores) to the fixative/spice mixture. For every quart of dried plant parts, add two tablespoons of the fixative/spice mixture. Store the potpourri in an air-tight container, and shake daily to ensure good contact between the fixatives and the plant parts. Allow this to mellow for four to six weeks, then display your potpourri in an attractive container. A container with a removable lid will allow you to enjoy the aroma from time to time, yet retain the aroma when the lid is on.
Have some fun with potpourris, using as many different aromas as you can, but not all in the same container. Try using the flowers from roses, larkspur, delphinium, cornflower, pot-marigold, nigelia, marigolds, peonies, chamomile, sweet peas, hyssop, bergamont, statice, strawflower, lilacs, honeysuckle and linden for a pleasant looking as well as smelling potpourri.
For scent, try the flowers and leaves from herbs such as artemesia, thyme, sage, rosemary, basil, achillea (yarrow), lavender, scented geraniums, mints, marjoram, verbenas, anise and fennel. Or use common fruits such as rose hips, hawthorn berries, juniper berries, grapefruit rind, orange rind and apples. Make sure the herbs and fruits are thoroughly dried to prevent mildew from establishing.
Use your imagination when selecting plants for your potpourri, and enjoy the aroma of your yard year-round.
Take any gardening class and your instructor will almost certainly tell you that it is better to water your lawn, garden, trees and shrubs deeply and infrequently, rather than giving each plant a tiny dribble each day. Sometimes instructors will go on to explain that by permitting the plant to dry slightly between waterings, you are forcing the roots to search for moisture, leading to development of a more extensive root system. There is a flaw in this reasoning, however, because roots never search for water. Why don't roots search for water? Because they're not that smart.
Picture the root system on a drought-stricken plant. It's rather difficult to accept that one fork might be saying to the others, "You go left, you go right, you go down and I'll stay here by the phone." As amazing as roots may be, they have not yet learned how to organize search parties or go on prospecting missions. The word "pro/spect" literally means "ahead/looking", and no one has yet shown roots to have foresight.
Why do roots grow where they do? It's purely a matter of opportunism. Give a root system a deep rich moist layer of soil and it will grow to fill it. When these same roots encounter a layer of parched chalky soil they will not advance even one millimetre into it. People may venture into a desert looking for a distant oasis, but a root just doesn't share this same sense of adventure.
Of course everyone knows that the roots of poplar trees are notorious invaders of buried sewage pipes. Does a poplar root encountering a pipe stop and ask itself if perhaps there may be a superb supply of nutrient-rich water on the other side of the pipe's wall, conclude that it's worth investigating, and proceed with a prospecting mission? Simply remember that the IQ of a root is roughly equal to zero and you can probably guess that roots don't decide to look for the water inside of pipes.
So how do they get in? Again it's pure opportunism. One tiny root happens to grow near a hairline crack in the pipe. Because the soil around this crack is slightly more moist than the adjacent soil, that root begins to branch and take full advantage of the pocket of moisture. With hundreds of newly-formed branches, one eventually happens to follow the ever-increasing moisture supply right up to - and through - the hairline crack. Jackpot! Once inside the root grows and branches madly to take full advantage of the riches it has stumbled onto. A perfectly sealed water pipe is safe from poplar roots because without water leakage, even the most invasive of tree roots pass right by, not even slightly suspicious that their may be moisture inside.
Deep infrequent watering benefits the development of a strong root system for two reasons. First of all, roots will only grow into moist soil, so the deeper you permit water to move into the soil profile when watering, the deeper you will permit roots to follow. Secondly, deep watering should be done infrequently because roots require oxygen. Although it may sound unbelievable, nearly half the volume of most soil is composed of tiny interconnected empty spaces. When the soil is very wet, this space is may be totally filled with water; when the soil is not so wet, this space is usually about half filled with air. It is the flow of air through these billions of tiny pores which permits roots to receive their vital supply of oxygen. Without adequate oxygen, the roots eventually die and we say the plant has drown.
How do you know when you've watered deeply enough? The best way is to let the sprinkler run for a couple of hours and then dig down in the soil to see how far the descending moisture front has travelled. On sandy soil the rate of water infiltration will be rapid; on clay soils, infiltration rates will be much slower. For a lawn, or vegetable garden you should determine how long your sprinkler has to run to thoroughly moisten the soil to a depth of 15 cm (6 inches) and never water less than this length of time. For trees, you should water for at least twice as long. Since the texture of your soil will determine how long you have to water, it is best if you calibrate these rates for your own particular site.
Standing in the yard, waving to passing traffic with a blasting hose for twenty minutes every summer evening may make you a popular neighbourhood personality, but it is doing absolutely nothing for your plants.
Some readers may have tried, unsuccessfully, to germinate apple seeds and seeds from woody ornamentals. Seeds of most of our trees and shrubs are incapable of germinating immediately after they are harvested. Some are incomplete and require a further period to complete the development of immature parts; some have a mechanical barrier to water, which is required for germination; and many cannot germinate because of some physiological "block" that inhibits germination. For seeds that require a development period, dry storage will usually suffice. Among other methods, stratification is used to remove mechanical moisture barriers and physiological blocks.
The term stratification is derived from the old practice of stimulating seed to germinate by placing alternate layers of moist sand and seed. Stratification involves placing the seed in a moist medium to simulate the natural conditions it "expects" from its native environment. Seeds from trees that shed seeds in the early fall, for example, require a warm moist treatment to induce germination. Those that drop in the late fall or early spring respond to a cool moist treatment. Depending on when they are shed naturally, some need a combination of warm and cool treatments, others require a growing period in between to allow root and shoot development.
Do-It-Yourself Stratification: Seed stratification is a simple technique, though it is not always easy to control. The modern method is to thoroughly mix seeds in moist peat moss. The peat moss should be barely moist to the touch. A ratio of 1 or 1 1/4 parts water : 1 part air-dried peat moss by weight is recommended. The mixture is stored in sealed containers such as polyethylene bags. The bags are simply stored at room temperature to provide the moist warm treatment. They can be placed in the household refrigerator if a moist cold treatment is required.
Moisture is obviously a key factor in the stratification process. In theory it is possible to increase the amount of moisture in the peat moss to speed up stratification. High moisture levels in the sealed containers, however, causes fungus growth that can harm the seed. Even at low moisture levels, you can expect some of the seeds to germinate in the sealed containers; these seeds will grow normally, if they are planted carefully.
Seed stratification can be a rewarding technique for the amateur to try. Keep in mind that if the seed germinates, the resulting plant will not be "true to type," that is, it will not be the same cultivar as its parent.
Here are some possibilities: Apple: If seed is stored over winter, it should be stratified in the refrigerator for 2 months before spring sewingCotoneaster: Stratify for 3 months at room temperature, then for 4 months in the refrigerator. Sow in the spring. Juniper: Stratify at room temperature for 3 1/2 months, then for 3 1/2 months in the refrigerator. Sow in the spring. Saskatoon berry: Seed can be stratified in the refrigerator for 3-4 months over the winter and sown in the spring.
Gardeners often have problems with the way their soil "handles." At one extreme is the heavy clay soil, which is sticky when wet and like concrete when dry. At the other extreme is the "beach sand," which needs constant watering and just doesn't seem to grow a good garden. These are known as problems of soil texture . Fortunately, soils with texture-related problems can be improved.
Soil Texture Classifications
Soil texture is determined by the relative proportion of sand, silt and clay found in a given soil. The term "texture" refers to the size of the individual soil particles and has nothing to do with the amount of organic matter present in the soil.
Sand is gritty to the touch and the individual grains or particles can be seen with the naked eye. It is the largest of the three size classes of soil particles. A soil in which sand predominates is classified, logically enough, as a sand-textured soil or simply a sandy soil. Sandy soils are coarse in texture.
Silt is smooth and slippery to the touch when wet, and the individual particles are much smaller than those of sand. These individual particles can only be seen with the aid of a microscope. Silt-textured or silty soils contain relatively large amounts of silt.
Clay is sticky and plastic-like to handle when wet. The individual particles are extremely small and can only be seen with the aid of an electron microscope. As you might guess, clay-textured, or clay soils, are rich in clay and fine in texture.
The three main soil texture classifications, then, are sandy, silty and clay. Sandy soils are coarse-textured, clay soils are fine-textured, and silty soils intermediate in texture. "Loam" is another soil texture classification. A loam soil contains considerable amounts of sand, silt and clay. It is the preferred texture for horticulture because of its ease of workability. Textures between these classifications are also often used in describing soil types, e.g., sandy loam or clay loam soils.
You can roughly estimate the approximate amount of sand, silt and clay in a soil by a simple method called "manual texturing." The texture is determined by the feel of the moist sample when rubbed between the thumb and forefinger. If the soil sample is predominantly sand, it will feel very gritty. If it is predominantly silt, it will feel smooth or slippery to the touch. And if it is predominantly clay, it will feel sticky. The Saskatchewan Soil Testing Laboratory includes a manual estimate of soil texture as part of its garden soil test.
Horticultural Characteristics of Soils
From a horticultural point of view, it is very important to be able to identify the type of soil you will be working with ‹ as noted above, you can do this yourself by the manual texturing method or have it done at the Soil Testing Laboratory. The horticultural properties of a sandy soil will be quite different from those of a clay soil.
A sandy, coarse-textured soil drains easily and quickly after a rain, is easily worked, and warms up quickly in the spring.
But sandy soil also has some disadvantages. It has a lower moisture-holding capacity than a clay soil and therefore must be watered more frequently. It has a lower nutrient-holding capacity than a clay soil and must be fertilized more often. When vegetative cover is lacking, it is subject to wind and water erosion.
A clay, fine-textured soil has the advantages of high moisture-holding and nutrient-holding capacity. If the soil in your vegetable garden has a large proportion of clay you'll probably need to spend less money on fertilizer and water.
As you might expect, a clay soil has disadvantages as well. A clay soil often has poor drainage. That means that the soil remains saturated with water after the spring thaw and after heavy rains. If this happens, plant roots will be deprived of oxygen and the general health and vigor of the plants will be reduced.
Clay soils warm up very slowly in the spring. This characteristic can mean a delay of a week or more in planting seeds in a vegetable garden or setting out annual bedding plants, in effect shortening an already limited Saskatchewan growing season.
Because of their high water-holding capacity, clay soils are also subject to alternating expansion and contraction due to alternating freezing and thawing. This can result in "heaving," whereby plants are pushed out of the soil, as well as the breakage of plant roots.
Crusting and cracking (due to drying) are also problems in clay soils. Crusting impedes root penetration and prevents seedling emergence. Cracking causes the tearing of roots and other plant parts.
Finally, clay soils are difficult to work if the moisture content is not "correct": If too wet, they are gummy and impossible; if too dry, somewhat like concrete.
Soils of all textures, but particularly clay soils, will compact under "heavy traffic" conditions, as when a pathway is made across a lawn or garden.
Improving the Soils
Both sandy soils and clay soils can be enormously improved by the generous addition of organic matter such as compost, well-rotted manure, or peatmoss. Spread a layer of organic matter 7 to 10 cm thick on the surface of the area to be improved, and then THOROUGHLY INCORPORATE IT INTO THE EXISTING SOIL. If you do not incorporate the organic matter, water will not percolate well and thus plants will grow poorly.
Keep in mind that excessive amounts of manure, especially if fresh, can raise nutrient and salt levels to a degree that may be toxic and therefore restrict plant growth.
As well, very large amounts of straw or peat moss may induce temporary nutrient deficiencies, especially of nitrogen. For this reason, nitrogen fertilizer is usually added at the same time to compensate for the temporary nitrogen deficiency.
By germinating plants indoors before spring, you can extend what would otherwise be a relatively short growing season (100 days) so that vegetables such as tomatoes, green peppers, and eggplant are more likely to produce ripe fruit.
Small seeds of any type usually stand a better chance if sown indoors simply because there is more control over the environment - no sudden changes involving wind, sun, rain, drought, temperature, or the neighbour's cat.
Starting seeds indoors gives the home gardener more choice over variety. While greenhouses and garden centres will usually offer the more popular flowers and vegetables, for unusual or older varieties it is often necessary to order and grow your own seed.
You should derive a great deal of satisfaction from raising your own plants. And it's a sure way to avoid boredom during those February-March doldrums when we're all counting the days until spring.
Containers used for seeding must have good drainage and be able to hold soil and water without falling apart. They should be about 7.6 cm (3 in.) deep to prevent soil and seedlings from drying out. Deeper containers will simply use up more potting soil and weight more. Square or rectangular containers use less space than round ones.
Homemade or recycled containers include wooden flats, cottage cheese or yoghurt containers, and milk cartons split in half lengthwise (be sure to punch drainage holes in the bottoms of these). Egg cartons, long the favourite of teachers, tend to be too shallow and dry out too quickly.
Non-reusable, commercially available containers - Peat pots are generally small and available in round or square form, individually, or in strips or sheets. They are bio-degradeable and ideal for plants such as melons and cucumbers which dislike disturbance when transplanted. Simply plant the entire peat pot. Cover the rim with at least 1.27 cm (.5 in.) of soil so it does not act as a wick which will allow the entire pot and contents to dry out through surface evaporation.
Peat pellets are made of compressed peat that expands to seven times its volume when watered. Available in 2 sizes ("Jiffy-7's" and "Jiffy-9's"), they resemble ginger cookies when dry and lumpy muffins when expanded. Simply drop a seed in the depression on the top of the "cookie," place it in a tray and add water. The "Jiffy'7's" expand to a diameter of 4.4 cm (1.75 in.) by 5.4 cm (2.12 in.) high. The "Jiffy-9's" are smaller. Because the entire pellet with the seedling is transplanted, root disturbance is avoided.
Reusable, commercially available containers - These include clay and plastic pots, cell packs and 10- or 20-row starting trays. Clay pots tend to be more expensive, heavier, and more breakable than plastic ones. Seeding into either will usually involve transplanting.
Cell packs are made of lightweight plastic and are partitioned into 4 to 9 individual cells or compartments which fit into a plastic drip tray.
The row starting trays are similar to a wooden flat, but made of plastic, with a ridge between seeding gutters which discourages the transfer of damping-off fungi. Because the trays have a limited number of rows, they may prevent the over-zealous from seeding more than can be really used (or happily transplanted). The row seeders usually come with both a drip tray and a plastic cover which help maintain humidity.
If they are not included as part of a kit, you should provide separate "drip trays" of galvanized metal or plastic to catch drips and make bottom-watering easier. Care should be taken that these not be kept permanently full of water, or the soil will become water-logged and the seedlings will be deprived of oxygen.
When re-using plastic or clay pots, wash them with hot, soapy water and rinse them prior to each new seeding season. If you had problems with damping-off or other diseases, an application of a 5% bleach (Javex) solution might be advisable.
Potting mixtures for seeding should be free of weed seeds, insects, soil-borne diseases, and toxic materials. They should be able to hold moisture and yet remain aerated; and they should be non-crusting.
Garden soil is not generally recommended for potting mixtures. In shallow containers, it tends to pack and crust. As well, garden soil often contains both weed seeds and fungi (which can result in dampening off.)
Generally a soil-less mixture is recommended for the first sowing and a soil mixture for transplanting. Soil-less mixtures usually consist of some combination of peat moss, perlite, and vermiculite. They are lightweight and uniform. Most components of soil-less mixtures have been heat-treated in some way and are therefore considered "sterile," they reduce the risk of damping-off, a common fungal disease affecting seedlings.
Although pure vermiculite may be used for seeding, a more usual soil-less mixture consists of 1 part peat moss and 1 part vermiculite or perlite. A mixture may also be made up of 1/3 peatmoss, 1/3 perlite, and 1/3 vermiculite.
Components should be thoroughly mixed and moistened with warm water several hours prior to seeding.
Seedlings are usually transplanted into commercially available potting soil, which consists of some combination of loam, peatmoss, perlite and vermiculite. Such mixtures are usually labeled "sterilized" or "pasteurized," indicating that they have been heat-treated to kill insects, weed seeds, and disease-causing organisms.
If you must use soil from your garden, moisten it and heat it to 180F (internal soil temperature) for 30 minutes prior to seeding or transplanting. Dry soil takes longer to heat (and smells worse!) Use a meat thermometer to determine when the soil has reached 180F. 180F will kill insect eggs and larvae, some weed seeds, and damping-off fungi. At higher temperatures beneficial organisms are killed and dissolved salts are released from the soil which may be toxic to plants.
Vermiculite, perlite, and peat moss do not contain the nutrients needed for plant growth. Once seedlings have germinated and are growing, soil-less mixtures will require the addition of fertilizer. Use a soluble, complete fertilizer with trace elements (also called micro-nutrients) such as 20-20-20.
Fertilize seedlings at 1/4 to 1/2 the recommended strength once a week when watering - i.e., if label directions indicate 1 teaspoon per gallon of water, use only 1/4-1/2 teaspoon. Always apply fertilizer to moist rather than dry soil.
Fast growing annual flowers and vegetables might require more fertilizer than slower growing perennials. It is always better to under-fertilize than to over-fertilize.
Damping-off is the name given to several types of fungi which attack young seedlings at soil level and rot the stems. The stems blacken and elongate, while the leaves above appear healthy. The entire plant soon topples over and dies. The disease spreads quickly and is easier to prevent than cure.
As noted earlier, heat treatment of garden soil can help prevent damping-off. Chemical control is also effective: sow the seeds and then allow the container, soil, and seeds to soak up a solution of No-Damp (oxime benzoate), a fungicide which controls damping off. No-Damp is registered for domestic use, has no systemic effect and little residue. Use according to label directions.
Other ways to help prevent damping-off include:
1. Provide good lighting and air circulation. A fan in the room will increase air circulation.
2. Prevent overcrowding by sowing seeds thinly and transplanting seedlings once the true leaves appear to give them more space.
3. Use commercially available seeding trays which consist of a number of parallel gutters into which media and seed are placed. Damping-off organisms do not generally cross over the plastic lips between gutters.
4. Cover the seeds with a thin layer of sterile media such as vermiculite.
Williams was a specialist in horticulture with the Extension Division. This column is provided as a service by the Extension Division and the Department of Horticulture Science, University of Saskatchewan.
Sowing Very fine seeds may be simply pressed into the potting mixture. Other seeds (unless they specifically require light to germinate) are usually covered to a depth of their own diameter. It's best to use the same potting mixture to cover seeds. This is easily done with an ordinary tea strainer. A dibble (a small wooden tool) may be used to press medium and large sized seeds into the soil. The eraser end of a pencil usually works as well. Avoid using a super-fine, dust-like potting media to cover seeds, as it may cake and harden, and prevent seedling emergence.
Water the containers with luke-warm water from the bottom after the seeds have been sown. To do this, place the containers in a sink with about 5 cm (2 in.) of water and leave them until the water has soaked up from the bottom to the surface of the potting mixture and the surface is damp. Allow the containers to drain before placing them under lights or in a warm place to germinate. Cover the trays with clear plastic to maintain soil moisture and humidity until germination occurs. Check them daily and gradually remove the plastic cover once the seeds have germinated.
Once seedlings have emerged from the soil, place them in full light. Unless you have a greenhouse, fluorescent lighting is recommended. Incandescent bulbs produce red light, which when used alone, tends to produce leggy plants. The bulbs also produces a lot of heat in comparison to the amount of light given off.
Fluorescent tubes come close to duplicating the color spectrum of sunlight. Plants produced under them are usually green and stocky.
Cool white and warm White fluorescent tubes, used together, produce the best light for plant growth. Cool white emits light in the blue wavelength while warm white emits light in the red range.
Most cool white and warm white tubes will last 18 months if operated 12 hours daily. Light toward the end of the tubes is weaker than light in the centre, and falls off even more as the tube ages. Dust on fluorescent tubes decreases their efficiency. Painting shelves and reflectors with a flat white paint will increase the amount of light reaching the plants.
Two 1.2 m (4 ft) 40 watt fluorescent tubes in a reflector will supply the required light. This setup will provide light for plants in an area .6 by 1.2 m ( 2 by 4 ft) on the table, counter, or stand below it.
Lights are easily attached from the ceiling or a stand using furnace chain and S-hooks. The S-hooks allow you to adjust the height of the fixtures upwards as the plants grow.
Generally, the light should be 7.6-10 cm (3-4 in.) above the plants during the first 3 to 4 weeks. This can be gradually increased up to 10-15 cm (4- 6 in.). Seedlings require more intense light than more mature plants.
Insufficient light results in legginess, excessively large gaps between leaves, and pale stems and leaves.
Plants usually require a certain 'photo-period' or time during which they have light. Generally, 14-16 hours of daylight ( or fluorescent lighting) is sufficient for seedlings. Any longer than this can be harmful. An automatic timer is a very worthwhile investment.
Remember, most seeds require a fairly warm soil temperature in order to germinate. Most will germinate at soil temperatures between 21.1 and 32.2C (70 and 9F), but there is a lot of variation among species. Check the optimum soil temperatures for the germination of a particular species. Once germination has occurred, the seedlings will grow better at a lower temperature, usually about 10 degrees lower than their germination requirements.
The heat from the fluorescent tubes usually maintains a temperature of at least 21.1F, (70F), which is sufficient for most plant growth. Temperatures toward the outside of the lighted area will be cooler, so plants requiring lower germination or growth temperatures can be placed on the outside, while those with higher temperature requirements should be placed in the center. Monitor the soil temperature during and after germination by using a meat or soil thermometer.
If the room in which plants are grown is very cold, and plants requiring a high germination temperature are being grown, bottom heat is advised. This can be accomplished by placing the flats near a furnace or heating register until germination occurs (keeping a careful check so that the media does not dry out.) If you are growing a large amount of seedlings, you might consider investing in a heating cable. The cable is usually set at 21.1F (70F) and is installed below the flats or containers, with a layer of vermiculite and hardware cloth over it. Costs will vary depending on length. Using a tent of aluminum foil over the lights and seedlings can raise the temperature as much as 20F.
Williams is a specialist in horticulture with the Extension Division. This column is provided as a service by the Extension Division and the Department of Horticulture Science, University of Saskatchewan.
Transplanting To reduce injury to young seedlings during transplanting, handle them as carefully as possible. It is better to pick up a young seedling by the leaves (while at the same time supporting the root system) rather than by the stem, which is easily bruised and broken. A popsicle stick is a useful tool for this purpose, although a small spoon is equally good.
As mentioned in an earlier article, seedlings are usually transplanted into commercially available, sterilized potting soil, which consists of some combination of loam, peatmoss, perlite, and vermiculite.
Transplant the seedlings into the potting soil, taking care not to bury the growing point. Press the soil firmly around each plant so it is in firm contact with the soil and able to absorb water and nutrients. If damping-off has been a problem, you might want to use, a solution of No-Damp. Water from below and allow to drain.
Spacing of transplants depends a lot on the size of the plants. Anywhere from 9 to 12 seedlings can occupy a container (24 is a reasonable number for a wooden flat.) Leave 5-7.6 cm (2-3 in.) between the plants. If no wilting occurs, place the containers back under the lights. If they appear wilted, allow them to recuperate for a day.
Hardening Off From this point on the young seedlings should be allowed to grow steadily until they are "hardened off" and transplanted outside. The hardening-off process prepares the plants gradually for outside conditions. During the hardening off period, the plants require a steady supply of water, nutrients, good light, and temperatures which are cooler than those under which they germinated.
Begin by slowing down the growth of the plants. Water them less often (taking care that they not be allowed to dry up) and withhold fertilizer during the last 7-10 days indoors. Reducing temperatures will result in less sappy, succulent growth.
if the plants are not in individual containers "block" them by cutting between them with a knife within the containers. This accomplishes two things. it reduces tearing of teh roots during the actual trlansplanting process and stimulates the formation of fibrous root growth within each plant's block of soil, better preparing them for actual transplanting.
Using a cold frame allows for a gradual process of acclimatization to sun, wind, low humidity, and temperature fluctuations. Begin with the glass or plastic cover closed, and covered with a thin layer or burlap, cheesecloth, or newspaper to provide shading. Gradually lift the cover more each day and remove the shading material as the plants beacome hardened.
Check the soil moisture daily as evaporation is much more rapid outside. Also keep a careful check for expected frosts, closing the cold frame lid and covering it with old blankets or 2-ply plastic should they occur.
Wait until all danger of frost is past. Depending on the cold tolerance of the species, this can occur from May 15 to June 15 on the Prairies. While the May long-weekend is the "traditional" date, it might be more prudent to wait until the first week of June for tender annuals such as green pepper, tomato, eggplant, cucumber and melon.
Water the seedlings and the site on which they are to be planted thoroughly the day prior to transplanting. The site should be moist but not sticky at transplanting time.
It's best to transplant on a calm cloudy day or in the evening. Plants will topple over and bake in the wind or the heat of the mid-day sun.
Water the plants and keep them shaded for the first few days. Using 48 oz. juice cans or 1 litre milk cartons from which the top and bottom have been removed will give the transplants protection for the first few weeks.
This was the final article in Sara's 4-part series on starting seeds indoors.
Williams is a specialist in horticulture with the Extension Division. This column is provided as a service by the Extension Division and the Department of Horticulture Science, University of Saskatchewan.
A mulch is any material, organic or inorganic, applied t the soil surface in a layer at least eight to ten centimeters deep. For the purposes of xeriscape, organic mulches are preferred to inorganic mulches. Inorganic mulches include stone or gravel, plastic, and woven landscape cloth.
A. The Inorganic
Stone and gravel collect heat, cause temperature increases and therefore increase cooling costs of the home and irrigation costs to the landscape during summer. (Plants do the opposite, shading and cooling). Weed seeds are easily blown into gravel or stone and soon establish themselves. Another problem sometimes associated with gravel on the Prairies is their high pH which may cause an iron deficiency or chlorosis in susceptible woody plants.
Woven fabrics and fiber mats exclude weeds and yet allow for water and air exchange. But if used under an organic mulch they prevent it from enriching the soil as it decomposes.
Plastic excludes air and water essential to plant growth. It breaks down over time or if exposed to sunlight. It should not be used under organic mulches.
For all of the above reasons it is generally recommended that organic rather than inorganic mulches be utilized in the xeriscape. It is also well to remember that, "Achieving water conservation by substituting plastic and gravel for living plants will not add enjoyment to your landscape or value to your home" (James Feucht, 1987).
B. Benefits of Organic Mulches
The benefits of an organic mulch are many, but the most important is the reduction of water loss by reducing surface evaporation. It is estimated that as much as 75% of rain falling on bare soil may be lost to plants through evaporation or run-off.
Organic mulches will also prevent annual weed growth by establishing a physical barrier so that weed seeds blown in will have difficulty establishing themselves. Likewise, seeds already within the soil will have difficulty penetrating upwards through the mulch. (Perennial weeds are not usually controlled by mulch and should be removed prior to applying the mulch layer)
An organic mulch will also insulate the soil surface against temperature fluctuations. In summer, a layer of mulch will cool the soil making it a more hospitable environment for root growth and beneficial micro-organisms. During spring and fall the mulch will prevent alternate freeing and thawing and associated "heaving" and plant damage.
Because of its "cushioning' effect, a mulch lessons soil compaction due to human foot traffic while weeding or working in flower, tree or shrub, or groundcover beds - or the vegetable garden.
It prevents mud or rain splash on flowers and fruit (such as strawberries). Mulches can also prevent wind and water erosion of soil.
As they break down and decay, organic mulches add to the soil fertility and improve its structure.
Mulches have design benefits as well. Many as aesthetically pleasing and provide visual interest through texture and color. At the same time they function to unify a planting or bed. This is especially true when the bed if first planted and the plant material is small and occupies only a small proportion of the space it will eventually use when mature.
C. Types of Mulches
Some of the characteristics to look for in a mulch: a substance which will not blow away (except near Kindersley where everything blows); one which looks pleasing (or can be "top-dressed" with a thin layer of something else which will look nice); is easy to apply; non-toxic; and will not act as a wick and draw moisture from the soil. If its free, cheap, or readily available, so much the better.
Among the mulches commonly used in the Prairies are:
Peat moss - the coarser grade is better than fine grades; apply when already moistened or it will blow away; excellent water retention but if allowed to dry out may act as a "wick" and draw moisture from the soil.
Grass clippings - excellent if applied 4 inches thick; certainly prevents annual weed growth and evaporation; may not look pleasing and therefore need to be cosmetically :top-dressed" with peat moss. If sprayed with 2,4-D, allow 30 days for herbicide to biodegrade before using.
Compost/manure - should be very well rotted and free of weed seeds.
Leaves - may be too coarse unless first pulverized; composted leaves may be better.
Wood chips - may be too coarse for fine perennials but excellent for tree-shrub borders; very long lasting and effective.
Commercial bark chips - expensive but fairly long lasting; better with trees and shrubs than perennials; attractive.
Hay and straw - coarse for ornamentals; better used for fruit and vegetables; may contain weed seeds
Evergreen needles and cones - nature's own; attractive, long-lasting, effective, and free.
Maintenance of a xeriscape is not much different from the normal maintenance which Prairie gardeners have done for decades. The emphasis may be slightly different in that the major function is reduced water consumption. Therefore, weeding and irrigation system maintenance and monitoring are high on the list. So is the annual renewal of the mulch layer as needed. Because drought-tolerant plant material also tend to use less nutrients, fertilizing is usually not a high priority in xeriscape maintenance.
Although the words "variety" and "cultivar" are often used almost interchangeable, they are different.
Both words indicate a plant that is somehow distinctly different from other member os its species Ø in colour, size, taste, disease resistance, date to maturity, storage ability, or even fragrance. Think of `Tiny Tim' tomato, `Patmore' green ash, `Thunderchild' flowering crabapple, `Queen of the Night' tulip, or `Super Cascade' petunias. Each is different in some meaningful way from other tomatoes, ash trees, crabapples, tulips or petunias.
The critical difference between a variety and a cultivar. however, is that a variety is found growing in the wild, while a cultivar is grown in cultivation Ø in our gardens.
The common chokecherry (Prunus virginiana) is an example of a true variety. Stands of this wide-ranging native plant can be found across much of North America. If you sample these plant going from eat to west, you will find that the fruit becomes darker and darker as you move westward. In Quebec, a fully ripe chokecherry is bright red. In Saskatchewan, the ripe fruit of the same species is dark purple or almost black. The wild chokecherries of the Prairies are therefore considered to be a black-fruited variety of the more widely distributed red-fruited species. Since this difference exists and maintains itself in nature, it is a true variety.
To indicate that they are a variety, prairie chokecherries are named Prunus virginiana var. melanocarpa. The "var." in the botanical name indicates that they are a variety. In this case the, variety name melano/carpa is constructed from two Greek roots meaning "black" and "fruit."
When a plant exists in cultivation and is propagated to maintain its particular characteristics., it is called a cultivar. The word "cultivar" was formed by linking the words "cultivated" and "variety" (cultivated variety). Almost all of the plants we grow in our yards and gardens are cultivars. This makes sense - your chances of discovering `Snow King' cauliflower, `Starfire' tomatoes, or `Centennial' roses growing wild in nature are slim to nonexistent. Although `Smoky' and `Thiessen' saskatoon berries were originally found growing in nature, they have been brought into cultivation, making them cultivated varieties, or cultivars.
Cultivar and variety names are always written with `single quotes.' This makes it clear that one is referring to a named cultivar of plant, and avoids confusion. If a rose breeder were to state that `Gertrude Jekyll' was the result of an unintentional cross between `Wife of Bath' and `Martin Frobisher,' failure to use single quotes could lead to rather curious and even libelous conclusions being drawn by some people.
Many vegetable cultivars are actually hybrids, which means they have been derived by special plant breeding procedures.
What is Done
Plant breeders usually select two distinct 'inbred lines' - plants which produce new plants from seed which are identical to each other and to their parent plant. Each of the two lines selected will be quite different from one another. The two lines are crossed, and the resulting seed is called 'hybrid,' 'F1' or 'F1: hybrid.'
Why It Works
Inbred lines have their particular characteristics fixed over years (generations) of inbreeding. One line may carry desirable characteristics such as earliness, hardiness, attractive color and high sugar content. While the second line may carry insect- and disease-resistance. When the two lines are crossed, the resultant seed will contain the characteristics of both lines; as well possess 'hybrid vigor' - the ability to resist environmental stress. When two cultivars which are not inbred lines are crossed, the offspring are usually variable in size and other characteristics. The hybrids from inbred lines are uniform and robust.
Drawbacks and Advantages
One of the main disadvantages of using hybrid seed is that you cannot reproduce the same quality of plants from seed you save to plant next year. Should you replant seed from your hybrid plants, instead of robust, uniform plants like the first generation, the second generation will be low in productivity and variable. Therefore you must always buy new hybrid seed each year. The suppliers, unfortunately, may gradually change their hybrid seed offering or may choose not to offer some hybrid you like.
Many gardeners think that the advantages of hybrids far outweight their disadvantages. It is often impossible to get uniform, robust plants with many desirable characteristics without using hybrid seed. For the most part hybrids are higher yielding, and of better quality than straight line cultivars.
There is an assumption on the part of some people that hybrids are not as good nutritionally as old line cultivars. As a result of this thinking, some seed suppliers are now promoting old inbred lines, or 'heritage cultivars.' In most cases, however, hybrids out-perform the heritage cultivars.