Vegetables

Facts About Potatoes
Potato Field

To understand the abnormalities of potatoes, we must first understand what is normal and what the healthy development of potatoes should look like.

Normal Tuber Initiation and Growth: Tuber initiation refers to the time at which tubers begin to swell at the end of rhizomes. This usually occurs from about mid-June to mid-July in Saskatchewan. The exact timing will depend on location, planting date, climate, soil type and cultivar.

Tubers form when the plant produces more carbohydrates than what is needed for top growth. Varying conditions can affect the plants causing a deficit of carbohydrates and resulting in uneven tuber formation.

The number of tubers initially formed per plant is about 15- 20, however only 5-10 mature tubers are normally formed per hill at harvest time. It is believed that many of the small tubers originally set are used by the growing plant as a source of nutrients or absorbed by larger tubers.

Optimum moisture and nutrient levels are therefore important for the maintenance and development of tubers very early in the growing season. Maintaining high levels of moisture (above 60 % available moisture) has been shown to produce a higher number of set tubers and in addition to an overall improvement in development.

Fluctuating temperatures, moisture, and level of nitrogen, especially in the tuber development stage can cause malformed tubers.

The Ratio of Nitrogen to Phosphorous: A balance of nitrogen (N) to phosphorus (P) is important to the development of tubers and plant growth. For example: Too much of N in relation to the amount of P (whether N is in excess or there is a lack of P), will produce excess top growth with poor tuber formation. An over-application of N can delay maturity by up to 15 days, which may be critical in Saskatchewan, considering our short growing season. Use fertilizers with a high level of P (middle number) in relation to N (first number) such as 11-48-0, 5-10-10, 6-12-12 or 5-20-20.

When planting, make a hole or furrow about 13 cm (5 in) deep; add 27 ml (1 1/2 Tbsp) of complete fertilizer (N-P-K) at the bottom of the hole, or 900 g/15 m of row along the bottom of the furrow. Place 2.5 cm (1 in) of dirt, then put in seed potato and top with soil. You may also broadcast the fertilizer over the garden plot at 7-9 kg/100 m2 and work well into the upper 15 cm (6 in) of soil. Avoid placing the seed potato in direct contact with the fertilizer.

Spacing: Spacing can influence the size and yield of tubers. Close spacing gives a higher yield per unit area in your garden but will produce smaller tubers. On the other hand, potato hills that are spaced too far apart, or patches where hills are missing may cause potatoes to grow too large, too fast, and become hollow in the centre. Plant stock pieces about 25-30 cm (10-12 in) apart in rows about 80 cm (32 in) apart with each seed piece about 42 g. Seed should not be cut more than once to reduce the fleshy surface area exposed to rot and decay organisms.

Example - About 2.25 Kg of potatoes cut in 42 g pieces is enough to plant a row about 12 m long.

Potatoes take 2-3 weeks to emerge from the soil when planted at a depth of 7-10 cm (3-4 in). Planting at this depth helps the young shoots from frost damage. Plant more shallowly in heavier soils, especially when planting early in the season. Planting too deep will delay the emergence of young shoots.

Water Requirements: A lack of water is one of the main causes of reduced yield. Cycles of hot dry weather, followed by heavy rains which cause rapid growth, resulting in rough, knobby, malformed or cracked tubers. On the other hand, high humidity and excessive rainfall may provide ideal conditions for diseases such as late blight.

Drought periods longer than 1 week can greatly reduce the growth of potatoes. On average, potatoes require about 2.5 cm of water per week. Water is especially important during the period of tuber enlargement.

A moist soil keeps tubers cool during hot weather and thus helps prevent certain diseases and disorders from developing.

Weeding and Hoeing: One good hoeing before plants emerge will save time later. Continue to hoe until the foliage covers most of the soil surface or when plants come into bloom. Besides controlling weeds, hoeing aerates the soil and allows better absorption and retention of water.

Hilling around the base of the plants prevents greening or sunburning of the tubers, in addition to providing some degree of frost protection. The hill that is formed should be broad and flat. Start far enough away from the plant, so as not to cut the roots or developing tubers.

REFERENCES:

Potato Production Guide; Alberta Agriculture; Edmonton; 1986.

Growing Garden Potatoes; Agriculture Canada, Publication 1559E; Ottawa; 1984.

Garlic In Your Garden

Garlic (Allium sativum) is a member of the onion family whose cultivation dates back to ancient Asia and the Mediterranean. Garlic was first introduced to the Americas in the 1500s. Botanically the garlic bulb is not a root but a series of cloves. Each clove consists of a bud enclosed in two modified leaves. One of the leaves is used by the plant as a food-storage organ. The other leaf forms a thin, dry protective layer. As garlic rarely produces seed, the clove is used to propagate the crop.

Types and Uses of Garlic

There are two types of garlic grown locally: Allium sativum or the common garlic and elephant garlic, Allium ampeloprasum, which produces an onion-size bulb with large, mild-tasting cloves. Both the bulb and the leaves can be used as a flavoring component in a tremendous range of food, from Caesar salad to your favorite curry dish. There is a wealth of folklore surrounding this food item. Garlic is thought to have many beneficial properties. The distinctive odor and flavor are the result of organic sulfur compounds. The lingering effects of this enjoyable herb are combated by consuming a grated apple, honey, or parsley.

Planting and Growing Garlic

Planting material can be obtained from a wide range of sources including seedhouses, local garlic growers, or supermarkets. Bulbs are "cracked" by hand, and individual cloves are planted. Only large, healthy cloves should be planted; the rest may be used in cooking. Before planting, check the clove for signs of Penicillium blue mold. This storage disease causes pitting of the clove and the production of an obvious powdery blue-green mold.

Discard any infected material, as it will decay in the soil. Plant the cloves 7.5 cm (3") apart, 5 cm (2") deep with 45 cm (18") between rows. Garlic can be planted as soon as the frost is out of the ground (early May). Some growers are fall-planting garlic in the hope of increasing their yields. Fall garlic is planted three weeks prior to freezeup. With fall-planted garlic, a good insulating layer of snow or a 10 - 15 cm (4 - 6") straw mulch is needed to help the garlic survive the winter. Elephant garlic is more sensitive to cold temperatures and may not survive Saskatchewan winters unless very well protected.

Garlic is a cool season crop that thrives in the cool weather of Saskatchwan.  Garlic can be grown on any soil that is suited to other vegetable crops, requires very little fertilizer, and is relatively insect- and disease-free

Planting and Growing Garlinc

Clove preparation: Garlic bulbs should be separated into individual cloves just prior to planting. As bulbs are separated or cracked, care should be taken to minimize bulb damage. Plant only those cloves that appear healthy and of good size, since the larger the clove planted the larger the resulting plant and bulb will be.

Spacing: When planting the cloves, place them approximately 3 inches (7-8 cm) apart within the row at a depth of 2-4 inches (5-10 cm). Between row spacing may be quite variable depending on space limitations and type of tillage equipment to be used. A 1 foot (30 cm) minimum space between rows is recommended.

Timing: Garlic can be planted any time between late August and early October. Some studies showed a reduction in clove survival as planting is delayed, which suggests that late August or early September may be the preferred planting time.

Fall cover: A minimum of 6 inches (15 cm) of snow is required to protect the garlic from the desiccation and freeze cycles that may occur throughout the winter. In areas prone to heavy drifting, inadequate snowfall or mid- winter thaws, a straw mulch may be used to enhance the level of winter protection. Straw mulches can introduce various weeds into the field or garden and require a fair amount of labour for its application and removal. A location with good wind protection is considered desirable.

Fertility: Garlic requires approximately 150 lbs/acre of nitrogen. The nitrogen is best split between 2 applications with 2/3 of the required amount applied at planting time and the remainder applied half-way through the growing season. The garlic also requires phosphorus at 80-100 lbs/acre, which is best applied prior to planting and worked into the top 3-4 inches of soil. Fertility levels should initially be determined by testing the soil. Additional fertilizer may then be applied in order to bring nutrient levels up to the required amounts.

Irrigation: During the growing season, approximately 2.5 cm of water per week is required for most soils. A sandier soil may require additional water during hot dry weather. Garlic grown under moisture stress will have reduced yields, especially when drought is experienced during bulb production. Water in the morning or mid-afternoon to allow sufficient time for the foliage to dry before nightfall in order to reduce disease susceptibility. As garlic matures, irrigation should cease otherwise bulb rot will occur.

Weed Control: Weed control is essential for good crop development. Garlic tends to be a very poor competitor against weeds but fortunately, there are herbicides are registered for use in garlic. Currently there are no herbicides registered in Saskatchewan for post emergent control of broadleaf weeds. This leaves cultivation, hand picking and hoeing as the only viable alternatives for broadleaf weed control. Deep cultivation close to the roots should be avoided to reduce chances of root damage.

Diseases: Seed borne viruses and fungi have the potential to reduce plant vigour and yields. Both may be present in seed material. Good quality seed should be free of most fungi but viral diseases are more widespread and unfortunately the only means of dealing with viral diseases is through viral indexing which is a costly procedure, involving tissue culture propagation of the garlic stock.

Cultivating Practices:  Garlic is quite drought-sensitive. A weekly application of 2.5 cm (1") of water may increase yields. In early August, reduce watering to let the plants dry down prior to harvest. Like most onions, garlic competes poorly with weeds. Weeds can be controlled by hoeing; however, as garlic is shallow-rooted, deep cultivation should be avoided. Mulching between the rows with straw or plastic may provide a degree of weed control. To prevent problems with bulb rots and root maggots, avoid areas of the garden where you have previously grown onions.

A common problem encountered by many garlic growers is the production of uncloved bulbs or "rounds." This is generally the result of planting cloves that are too small, or poor growing conditions throughout the season. Planting a cultivar that is not adapted to local conditions may also result in excess production of rounds. If rounds are left in the ground over winter or lifted and planted the following spring, they will probably develop into cloved bulbs.

Harvesting

When garlic is mature, leaf tops will begin to dry, discolour and bend towards the ground.  Garlic should be harvested when the lower 1/3 of the leaves are yellow and have died back in this manner.

If harvesting by hand, use a fork to loosen the soil and facilitate lifting. If harvesting is delayed too long after the tops have died back, the bulbs may rot.  A further delay in harvesting may  result in the shattering of the bulbs.

Curing and Storage

Once harvested, the bulbs must be cured properly in order to prolong storage life. Curing can occur in the field in warm, dry weather by taking advantage of natural air movement.  Bulbs should be cured for 10-14 days at 27°C in a well-ventilated area. After curing, the tops and roots should be trimmed and the dried outer layers of skin may be removed to improve the bulb's appearance. Bulbs are stored in the dark at 0°C and 60-70% relative humidity in woven "onion" bags. Smaller quantities can be braided and hung up in the kitchen for use throughout the winter. If a braid is desired, the garlic must be harvested while the leaves are still green, as dry leaves are difficult to braid.  If proper storage requirements are met, garlic should store 4-6 months.

REFERENCES:

  • Garlic Production on the Prairies; Dr. D.R. Waterer; University of Saskatchewan; July l993.
  • Garlic Production; B.R. Schumacher and J. Uyenaka; Ontario Agriculture and Food; Agdex 258/13; March 1989.
  • Garlic Production in Saskatchewan; Dr. D.R. Waterer; University of Saskatchewan.

Revised April, 2013

Growing Sweet Corn
Growing Sweet Corn

Most homeowners wait patiently for their first taste of home-grown corn on the cob. Sweet corn is one of the most desirable garden vegetables which is why so many different varieties are available through seed catalogues. Though sweet corn is a warm-season crop (heat-loving), it can be grown very successfully in this area. Here are a few hints to help ensure crop success:

- do not plant corn into a cold (less than 17C) wet soil. These conditions favour the growth of fungi which can rapidly rot the seed. Ensure the seed is fungicide-treated if planting into cool soils.

- soaking seeds in water for about 4 hours may speed up germination. If you soak your seeds, you must plant them in warm moist soil; dry soil will inhibit germination. More simply, plant dry seeds and water thoroughly.

- plant corn in a square or block pattern rather than in long, thin rows. Corn is wind-pollinated, and square planting patterns result in greater pollination. A minimum of 100 plants in a block is suggested for optimum pollination. Missing kernels in a corn cob are an indication of poor pollination.

- do not remove the tassels at the top of the plant; the tassels constitute the male portion of the plant which supplies the pollen. The fine, yellow dust (pollen) shed by the tassels falls onto the silk of the cob, which is the female portion of the plant. Each silk thread is attached to a kernel. If no pollen falls onto the silk, no kernel will form. Shaking the plants when the pollen is being shed can help increase pollination.

- choose varieties that will mature within our approximately 100-day growing season. Most seed companies are located in eastern Canada, where growing conditions are more favourable than ours. A variety listed in a catalogue as maturing in 55 days will usually require 85 days in Saskatchewan. It is wise to add 30 days to the listed maturity date to determine the maturity date in Saskatchewan. This rule of thumb will change from year to year, but overall proves to be fairly reliable.

- since corn is wind-pollinated, cross-pollination can occur if different types or colours (yellow, white or bi-coloured) are planted close to each other. In order to ensure maximum quality, keep each type (normal sweet corn, sugar-enhanced and super-sweet) well isolated from each other - preferably by at least 30.5 m (100 feet) apart. It is also essential to keep popping corn, ornamental corn, and field corn well isolated from sweet corn varieties. If cross-pollination does occur, sugar levels, colour, popping quality and other characteristics will not be as anticipated. To avoid isolation, different types of corn can be planted close together as long as their maturity dates have a difference of at least 7 days. This way, when one variety is shedding pollen, the other variety will not be receptive to pollen.

- as soon as the cobs are harvested, the sugars in the kernels quickly convert to starches. This produces a less sweet product. To ensure maximum sweetness, cobs should be immersed in ice cold water as soon as possible after picking, and left in the water until eaten. Shade from hot sun as much as possible. Many homeowners take pails of water and ice out to the garden when harvesting corn. Try it - it's well worth the effort!

Due to consumer demand, plant breeders over the past decade have significantly improved the quality of sweet corn. Numerous types of sweet corn are now available to homeowners, and it is important to know about these types in order to obtain maximum quality.

Normal Sweet Corn or Sugary Normal: Abbreviated Su, Su+, Su++. These have been, and still are, very popular with home gardeners, partly because they will germinate in cool soil (10C). Varieties have varying degrees of sweetness, but unfortunately the sugars convert to starches after harvest quite quickly. A new group of normal sweet corn called 'All Sweets' is much sweeter than the average for this type.

Sugar Enhanced: Abbreviated SE or EH. This type is most prized for its very tender kernels that are easy to chew. The sugar content is greater than normal sweet corn, reportedly much the same as 'All Sweets'. After harvest, sugars are not converted to starches as fast as normal sweet corn varieties. Sugar-enhanced varieties should not be planted as early as normal sweet corn varieties, for they need a warm (17C) soil temperature for germination.

Supersweet or Shrunken: Abbreviated Sh2. This type of sweet corn produces kernels that are at least twice as sweet as normal sweet corn, and also sweeter than sugar-enhanced varieties. The sugars do not convert to starches nearly as fast after harvest. Unfortunately these varieties need a warm (17C) soil temperature for good germination. Isolation from other corn types is essential!

Some of the varieties that have performed well in this area, and that are recommended for homeowners include: Buttervee (Su++), Classic Touch (Su+), Maple Sweet (SE), Northlite (Su), Polarvee (Su), Spartan (Su++), and Sweetie (Sh2). This list is by no means complete, as many other varieties are likely suitable, but have not yet been tested by the Department.

Harvesting of Vegetables

Harvesting vegetables may seem like a simple task. "You just pick them when they look right". However, the goal is to harvest vegetables when they are at their best - the most tender and sweetest. A number of vegetables if not picked at the optimum time become stringy, woody, or tasteless, which nullifies the hard work put into planting and taking care of them.

Here are a few guidelines to ensure that vegetables are harvested at their optimum.

ASPARAGUS: If plants were started from root crowns, you may be tempted to harvest in the second year, although it's advisable to wait until the third year. Plants that are started from seed, require at least 3 years before the harvest of the spears. The spears may be harvested over a 2 week period during the third year. In the fourth and subsequent years, harvest may be extended to four or more weeks. Cut a spear about 1 inch (2.5 cm) below the ground when the spear's length is about 7 inches (17.5 cm). This will give an edible shoot of 8 inches (20 cm). Crowns may be easily damaged by the knife, so some people prefer to break off the spears at soil level. Eat asparagus immediately, or store them by immersing the cut ends in water and refrigerating. Once well established, this perennial vegetable can be harvested for a period 6-8 weeks each spring.

BEANS: Green beans indicate maturity by the smoothness and greenness of the pods. Snap beans are ready to pick if they snap easily when bent in half. Once pods begin to turn yellow and the beans start to become apparent (a corrugated look), the snap beans will be tough. Yellow beans varieties should also be picked before they appear corrugated. Days to maturity for beans are: bush beans, 50-60 days; pole, 60-90 days; limas 80- 100 days.

BEETS: Beets may be harvested as soon as they reach 1 inch (2.5 cm) in diameter. They are excellent at 2 inches (5 cm), but over 3 inches (7.5 cm) they become tough. The tender inner leaves can be used for pot greens. Beet greens make excellent borscht (beet soup).

BROCCOLI: Cut broccoli when the individual buds in the clusters are still tight. Once buds open, the broccoli has a stronger flavour. The first crop will consist of the central head with 5 inches (12.5 cm) of stem. A second crop can be harvested for several additional weeks, consisting of side shoots that have 3-4 inches of stem. Broccoli should be picked every 3-4 days so the crop does not get out of hand. (Any surplus broccoli can be frozen once blanched).

BRUSSELS SPROUTS: You may start picking the lower sprouts when they are between 1 to 1.5 inches (2.5-4 cm) in size. Sprouts should be bright green and firm. If the weather stays cool, one could expect 100 of these "tiny cabbages" per plant.

CABBAGE: These may be harvested as small as 4 inches (10 cm) in diameter and continued until 6-10 inches (15-25 cm). The heads should be firm at harvest, but don't wait too long. A prolonged harvest may result in split heads. Maturity may take 2-3 months, depending on the year.

CARROTS: Tiny sweet carrots can be harvested at 3-4 inches (7.5-10 cm) long. The remainder can be allowed to grow to about 1 inch (2.5 cm) in diameter. Once the carrots reach 1 1/2 inches (4 cm) or larger, they will be woody. Maturity time from seed to harvest is 65-80 days depending on the carrot variety and environmental conditions such as weather.

CAULIFLOWER: The head is made up of small segments resembling cottage cheese curds. For the best flavour, these segments should be tightly packed, white or ivory in colour without brown spots present. When the heads start to form, tie the leaves together at the top to form a teepee. This will keep the sun out and prevent the head from yellowing. Transplant to harvest time is approximately 70-80 days or up to 100 days if cool weather persists.

(SWISS) CHARD & SPINACH: Pull off outer leaves as they mature, making sure to leave a central tuft of leaves to maintain the plant. Chard leaves are best harvested when they are 6-10 inches (15-25 cm) long and spinach 4-6 inches (10-12.5 cm) long. Swiss chard and spinach need 45-65 days to mature.

CORN: Harvesting corn at the right time can be vitally important when it comes to flavour. The first thing to watch for is pollination which is indicated by clouds of pollen erupting when you walk through the corn patch. About 3 weeks later, the silk will turn brown. Maturity can be tested by peeling down the husks at this time. Pop a kernel 2 inches (5 cm) from the top end of the ear with your fingernail. If the fluid is watery, it is still too early and you will want to wait a few more days; if the fluid is milky, the corn is at the right stage for eating; but if it is the consistency of toothpaste the corn has gone starchy and would be best used as creamed corn or used in chowders. The milky kernel only lasts for a few days so you don't want to delay harvesting.

After picking the cobs, cool them as quickly as possible, by plunging the ears into ice water and store in the refrigerator. Once cobs are picked, they immediately start changing sugars into starches, especially in warm temperatures. Corn requires 65-90 days to mature, depending on variety and environmental conditions.

CUCUMBERS: Cucumbers should be picked when they are still green and about 3 inches (7.5 cm) long for sweet pickles, 6 inches (15 cm) for dills and 8 inches (20 cm) for slicing. Picking 4-5 times a week will encourage continuous production. Do not leave mature fruit on the vine. Cucumbers are past their optimum stage once they turn yellow, form a tough skin and have tough seeds. Days to maturity vary between 55-70 days.

GARLIC/LEEKS/ONIONS: Green onions are best harvested when the stem reaches the thickness of a pencil. Leeks are harvested when the stem diameter reaches 1/2 - 1 1/2 inches (2-4 cm). Garlic is ready to be pulled when 1/3 of the top has died back.

The remainder of onions may be gathered as needed or when tops start to bend over and yellow. If they are still actively growing by the beginning of September, the tops should be bent over to start a bulb curing process. Onions should not be subjected to a heavy frost or the bulbs will be ruined. If they do not cure on their own or conditions are not favourable for outdoor drying, they may be spread out on the floor in a warm dry building preferably with a forced flow of warm air.

Garlic requires a curing period of about 20 days at 200C (or 10-14 days at 270C) with a lot of air movement.

LETTUCE: The outer leaves should be harvested before yellowing or browning occurs. If the stand is thick, entire plants may be cut off, allowing the remaining plants more room to develop. Head lettuce should be firm before it is picked. In semi-heading types the centre will not become firm, so you may harvest as soon as a soft head forms. Leaf lettuce is ready to eat 40 days after seeding. Approximately 100 days are needed for large heads to form.

PEAS: Harvest the pods just before they appear round in cross section, while retaining their bright green colour. Chinese and snow peas, whose pods are eaten, are picked when pods are flat and about 1.5-2.5 inches (4- 6.5 cm) long. Pods longer than 3 inches (7.5 cm) are too fibrous. (Pick the pods carefully so as not to break the the vines and do not leave overripe pods on the plants.) Pods can be picked 60 days after planting.

BELL PEPPERS: Peppers may be harvested with a sharp knife; at any size when the fruit is dark green. If you would like a few red peppers for a nice colour contrast in salads, allow some of the fruit to remain on the plant until it turns red. Maturity time needed for transplants is between 75-85 days. Small peppers grow slowly so you will need 6-8 weeks from seed to transplant size.

POTATOES: For fresh tasting "new potatoes", dig up the tubers when the flowers form on the plant. For fully mature potatoes, wait until the top growth starts to die back. If you want to store the tubers for a prolonged period of time it's advisable to wait until the crop matures. Mature tubers will have a firm hardened skin, will be less susceptible to injuries and will store better than immature tubers. It is best to harvest before the first killing frost. If the growing season has been too short to mature the tubers naturally, the tops may be prematurely killed by cutting them, once tubers have reached an acceptable size. The skin will harden sufficiently if tubers are left 10-14 days in the soil.

PUMPKINS: Wait until the fruit is a deep orange. If you cannot sink your fingernail easily into the rind, the pumpkin is ripe enough to put directly into storage. By this time, the vines will usually be drying. If the pumpkin is not mature, it may be left on the vine until after a light frost. However, if the average daily temperature is below 150C growth will be reduced or eliminated and the benefit of covering the plant will be questionable. If a heavy frost threatens and you must harvest earlier, leaving the pumpkin at room temperature for a few weeks will allow the rind to harden. Pumpkins may be stored at 100C with 70 to 75 percent relative humidity.

RADISHES: Thinning and eating may start when radishes are the size of marbles. Radishes may harvested up to 1 inch (2.5 cm) in diameter; beyond that size they become pithy and strongly flavoured. Radishes mature 25-30 days after seeding.

SQUASH/ZUCCHINI: Common green zucchini is best harvested when 6-10 inches (15-25 cm) in length, yellow types at 4-7 inches (10-17 cm) and patty pan (scallop types) when 3-5 inches (7-12 cm) in diameter. Summer squash larger than this will develop hard skins and large inedible seeds. Spaghetti squash may be harvested when golden yellow and banana squash picked when golden orange. Winter squash are cut with a few inches of stem, after the vines have died back in late summer or fall. Skins should be hard enough to resist your fingernail. Frequent picking will encourage continuous production. Summer squash requires 50 days to mature, whereas winter types require 80-120 days.

TOMATOES: Tomatoes reach full flavour when uniformly red, but you may wish to pick some earlier for frying. Overripe fruit may used for processing into juice, catsup or sauce. One can expect a full red colour to develop 5 days after the first signs of pink show on the fruit. If frost is approaching and you still have green fruit on the plant, pick the tomatoes with 2 inches (5 cm) of stem attached or pull the entire plant. Store in a cool dark place (inside a brown paper bag or under brown paper works well) and allow to ripen. Ripening time from large transplants until harvest will range from 55-75 days.

 

REFERENCES:

  • When to pick a vegetable, by Warren Asa.
  • Step-by-Step, Planting Asparagus, by Rosalie H. Davis.
  • Hortideas; September 1990.
  • Growing Garden Potatoes; Agriculture Canada; Publication 1559 E.
  • Harvesting and Storage of Onions, by D.H. Dabbs; Department of Horticulture Science; University of Saskatchewan; Saskatoon.
The Pumpkin Comes in all Shapes and Sizes, by Grant Wood; University of Saskatchewan.
The History of Cabbage

Reports of modern agricultural scientists imposing changes upon the food plants we eat are frequently in the news. While the rate of change in the plants we grow may be more rapid today than ever before, we should not forget that humans have imposed changes upon the plants we have grown for thousands of years. In fact, some of the more outstanding changes that human have made in crop development have not been made as a part of a planned research strategy, but have been accomplished by the simple act of collecting seeds from those plants we like the most, and growing them more frequently than the plants we don't like quite as much. The simple act of choosing one plant over another when propagating has an enormous effect on the improvement of a particular crop or plant, and long before people had a clear understanding of plant genetics, simple selection of desirable traits in the plants began to develop vast improvements had been made. By simply selecting one plant over another when propagating, small differences can slowly be introduced into a population, with the small changes accumulating over time to produce some dramatic results.

Our common cabbage-like vegetables provide an excellent example of remarkable crop improvements that was accomplished by simple long-term selection with no real goal in mind, but simply by people growing those plants that had the features that they most desired. Although they appear very different, kale, cabbage, kohlrabi, cauliflower, broccoli and Brussels sprouts are all the same species of plant. These plants are all known botanically as members of the species Brassica oleracea. The only difference between these plants are the differences that were introduced over thousands of years of human cultivation and selective propagating.

In the wild, the Brassica oleracea plant is native to the Mediterranean region of Europe, and is somewhat similar in appearance to a leafy canola plant. Sometime, soon after the domestication of plants began, people in the Mediterranean region began growing this first ancient "cabbage" plant as a leafy vegetable. Because leaves were the part of the plant which were consumed, it was natural that those plants with the largest leaves would be selectively propagated for next year's crop. This resulted in large and larger-leafed plants slowly being developed as the seed from the largest-leafed plants was favoured. By the 5th century B.C., continued preference for ever-larger leaved had led to the development of the vegetable we now know as kale. Kale is known botanically by the name Brassica oleracea variety acephala which translates to mean "cabbage of the vegetable garden without a head."

Kale continued to be grown as a leafy vegetable for thousands of years, and is still grown today. As time passed, however, some people began to express a preference for those plants with a tight cluster of tender young leaves in the centre of the plant at the top of the stem. Because of this preference for plants in which there were a large number of tender leaves closely packed into the terminal bud at the top of the stem, these plants were selected and propagated more frequently. A continued favouritism of these plants for hundreds of successive generations resulted in the gradual formation of a more and more dense cluster of leaves at the top of the plant. Eventually, the cluster of leaves became so large, it tended to dominate the whole plant, and the cabbage "head" we know today was born. This progression is thought to have been complete in the 1st century A.D. This plant was named Brassica oleracea variety capitata, which translates to "cabbage of the vegetable garden with a head."

At about the same time, in a part of Europe near modern Germany, kale plants with short fleshy stems were being selected, resulting in fatter and fatter stems. Selection on this basis eventually led to the ancestral "cabbage" plant developing into the vegetable we know as kohlrabi. The kohlrabi plant was named by botanists as Brassica oleracea variety caulorapa, with the last word meaning, "stem turnip." Both cabbage and kohlrabi have been cultivated for about two thousand years.

Some time in the past thousand years, as a preference developed in southern Europe for eating the immature flower buds of these plants. Selection pressure favouring production of plants with large tender flowering heads was imposed by some growers. By the 15th century, the modern vegetable we know as cauliflower had developed. About a hundred years later, broccoli had been generated in Italy. Cauliflower is named Brassica oleracea variety botrytis, with the last part of the name referring to the fact that a cauliflower curd is was thought to resemble a bunch of grapes. Because broccoli was developed in Italy, it was named Brassica oleracea variety italica.

Finally, in the 18th century, selections of cabbage plants which produced a large number of large, tightly packed leafy buds along the main stem were made in Belgium. These became known as Brussels sprouts and were named Brassica oleracea variety gemmifera, meaning "garden cabbage bearing gems."

From the example with cabbage, we can see that without detailed knowledge of plant breeding or genetics, simple selection by the people growing the plant over seven thousand years, led to the development of six dramatically different vegetables which are all members of the same species, Brassica oleracea.

Horseradish

This hardy perennial produces a thick root which, when ground up, is often served with roast beef. It is one of the more aromatic herbs, with some medicinal qualities. Anyone who has grown the plant will know that a small patch is more than sufficient to meet family needs, for it can easily overtake the garden plot. A thorough, deep cultivation will help to control its spread.

Soil Preparation

A deeply worked, moist loam with a high organic matter content is the ideal soil for horseradish. Soils suitable for rhubarb and asparagus will suffice for horseradish.

Planting

In the fall, cut off the lateral roots which have developed on the main tap root. Tie the lateral roots into a bundle and bury them in the soil at least 7.5 cm (3 in.) below the soil surface; a mulch applied over these roots will help prevent winter injury. A more reliable method is to store the root bundles in a root cellar. Early in spring, plant these root-cuttings in a vertical position, with the larger end upward. Cover them with 2.5 to 5 cm (1 to 2 in.) of soil. The thicker lateral roots are more desirable because they will yield a larger tap root in the fall. The within-row spacing for the plants is 46 cm (18 in.). One row of horseradish is usually sufficient.

Cultural Requirements

If the soil has been well prepared with rotted manure (5 to 7.5 cm/2 to 3 in. incorporated in to the soil), commercial fertilizer will not be required. Adequate moisture will result in optimum yields, but the plants will produce edible roots with minimal watering. Excessively good growing conditions will enhance the spread of this plant.

Harvesting

Most of the root growth occurs in late fall. Therefore, delay harvesting until late September. At this time carefully dig around the plant. There will be many lateral roots attached to the tap root. Try to dig up as many lateral roots as possible with the tap root. The tap roots can be stored in a cold room like potatoes. The lateral roots are removed and discarded, or used for root-cuttings for next year's crop.

It is unlikely that you will succeed in removing all of the lateral roots from the ground during harvesting. If they do not freeze over the winter,the roots left in the ground will produce new plants the next spring. In this way, the horseradish plant can become a hard-to-eradicate weed - unless it is kept confined by deep cultivation.

JERUSALEM ARTICHOKES

This perennial vegetable produces a small tuber similar to a potato. It is a member of the sunflower family - a close relative to the wild sunflower that grows in many parts of Saskatchewan. It not related, however, to the artichoke (Globe artichoke) found in food stores. The mature Jerusalem artichoke may reach a height of 1.8 m (6 ft), producing a sunflower-like, yellow flower-head late in the summer.

Jerusalem artichokes can be boiled or baked in their jackets like potatoes; they can also be served sliced raw in salads

Soil Preparation

Any soil that grows good potato crops will also grow good Jerusalem artichokes. A deeply worked soil which has had an adequate amount of well-rotted manure added is ideal. Incorporate 5 to 7.5 cm (2 to 3 in.) of the manure into the soil. Heavy (clay) soils are not the most suitable but the addition of organic matter will greatly improve such soils for growing artichokes.

Planting

The small, rough tubers similar to potato tubers are planted whole or cut. Leave at least one eye per piece. Planting is done in early spring. Tubers are set about 7.5 cm (3 in.) below ground level in rows 91 to 120 cm (3 to 4 ft) apart. The in-row spacing should be about 61 cm (2 ft). The plants require this much space because, as noted earlier, they can attain a height of 1.8 m (6 ft).

Cultural Requirements

The watering and fertilizing requirements for horseradish also apply to Jerusalem artichoke.

Harvesting Most of the tuber growth occurs in late fall. Therefore, as with horseradish, delay harvesting until late September. Start digging about 1 m (3 ft) from the base of the plant. Dig carefully to avoid damaging the tubers. Damaged tubers will soon spoil in storage. Cold, moist storage conditions are a necessity, as Jerusalem artichoke tubers dry out very readily. Small tubers can be left in the garden over winter. If they do not freeze, they will produce new plants in the spring. Mulching is recommended in exposed areas to prevent winter damage.

Like horseradish, the Jerusalem artichoke can become a troublesome weed. Some tubers are likely to escape harvesting, and growth can get out of control if it is not confined by deep cultivation.

Peppers in the Greenhouse

The cold wind has all but blown away the memory of the taste of summer's vine-ripened vegetables and fruits. But with a greenhouse, crops like peppers and tomatoes can be grown year- round.

If you have a small greenhouse, consider small-scale production of petters or tomatoes.

While soil is fine in the garden, it is not well suited as growing medium in a greenhouse: it does not allow adequate aeration and usually harbours disease. Most growers use a soilless mix, which had the advantage of being lightweight and disease-free. But because soilless media do not provide or store nutrients, these must be supplied as either a slow-release fertilizer or, more commonly, in the water applied to the greenhouse plants.

Although seed can be sown in late summer for early winter production, fruit produced during months of low light conditions are often small or deformed. Supplemental light can be used to improve fruit quality during months with limited light, but this adds to the cost of production. See the sidebar below for a more cost-efficient production schedule which does not require artificial lighting and involves only on pepper crop per year.

A daily application of fertilizer solution is recommended. Small- scale growers should apply 20--20--20 with macronutrients according to label directions. Larger operation should apply fertilizer at the rate of 225 ppm nitrogen, 40 ppm phosphorus, 350 ppm potassium, 175 ppm calcium and 40 ppm magnesium.

The climate within the greenhouse will influence the quality of the fruit. A relative humidity of 75% is ideal. Lower humidity will decrease growth and stimulate flower production, creating a large fruit load at the expense of a strong , healthy plant. Extremely high humidity will encourage disease.

Different temperature are required of the plant's life cycle. For optimum germination, the media temperature should be 26°C. After germination, this should be reduced to 24°C. Once the crop is transplanted into the greenhouse, the root zone or media temperature should be reduced to 21°C, with a daytime air temperature of 23°C and a nighttime air temperature of 19°C to 20°C. To stimulate fruit set. maintain an air temperature of 16°C at night and 23°C during the day.

Light conditions greatly influence the length of time it takes seedlings to reach the transplanting stage. Seedlings transplanted into the greenhouse from January 10 to April 15 need to be 85 days old, whereas seedlings sown after April 15 are typically only 50 days old when transplanted.

Once transplanted, and in order to support fruit development, plants must build a strong root system. and large leaf area. To maximize production, prune each plant to a two-stem system. The two strongest stems are selected to be fruit bearers and are attached to strings extending from the base of the plant to wires located 2.5m above the bench. These stems are permitted to branch, but all additional stems should be removed. Lateral shoots on the first 5 to 7 nodes of the plants should also be removed. Above the seventh node, simply remove the laterals to leave only one leaf/lateral.

Once the plant has four or five branches it is ready for pepper production. To encourage fruit set. gradually decrease night temperatures to 16°C over a period of three days to avoid shock. Once the fruit has set,. raise the night temperature to 19°C and the day temper to 22°C or 23°C to encourage fruit growth. A maximum of two peppers per tem is recommended for the fist fruit set. A larger fist set will decrease future yields. After the second fruit set. The plants should be strong enough to handle all fruit that is set. In full production (approximately six months after planting), the maximum load is five peppers per stem, To avoid "flushing" (a period of heavy fruit followed by a period of light fruit set), do not increase the temperature after the fist fruit set. A flushing pattern can also be avoided if all stages of fruit are present on the plant during production.

Harvest pepers with a sharp knife. cutting the junction between the fruit stem and the main stem. Fruit shoudl be picked when theya re 85% to 90% coloured since additional ripening will occur off the vine.

Cultivars for greenhouse production:

red: `Cubico,' `Mazurka,' `Delphin'

green to orange: `Eagle,' `Arianne'

green to yellow: `Kelvin,' `Goldflame,' `Rarantella,' `Luteus'

purple: `Violetta'

Perennials to Grow: Asparagus

Perennial vegetables persist year after year and survive winter temperatures, though some may require protection over winter. They do not require planting each spring, and a planting should last many years.

Asparagus is one of the most valuable perennials for the garden. It is harvested starting early in May, when fresh vegetables are scarce. Plants are not difficult to grow and will thrive under a variety of conditions. They tolerate drought, though the yield and quality are greatly reduced. A good supply of water will help to produce a large yield of juicy, crisp shoots for immediate use, quick-freezing or canning. With proper care, an asparagus bed should produce for 20 years or more.

Soil Preparation

The best type of soil for asparagus is a deep, rich, well-drained, sandy loam. Heavy (clay) soils are reasonably satisfactory if the top layer is of good depth (15 to 20 cm/6 to 8 in.) and an abundance of organic matter has been incorporated into the soil. Asparagus is a heavy feeder and requires a rich soil that is well prepared before planting.

A deep soil is necessary because asparagus is a deep-rooted plant. Good drainage is essential, and while flooding for a short time in the spring may be permitted, the surface water must be removed quickly during the growing season. Perennial weeds must be eliminated the year prior to planting. The ideal site should have full sun exposure.

The incorporation of a high-phosphorus fertilizer is suggested the summer before planting. The second number in the fertilizer formulation indicates phosphorus percentage, so choose a fertilizer with a high second number, such as 11-48-0. Also at this time, large quantities of well-rotted manure should be worked deeply into the soil.

Propagation

Asparagus is propagated from seed by the nurseries and can also be similarly propagated by the home gardener. It is generally more convenient, however, to buy the plants. The purchase of 2-year-old plants permits a saving in time of 2 years, and the cost of such plants is usually sufficiently low to justify the expenditure. Plants of this age are preferable to older ones and they may be obtained from most nurseries, garden centers and farmers markets. Volunteer seedlings at the base of an established planting are a good source of young plants but can become a nuisance if allowed to spread without control. Plants are either male or female ("dioecious"), with only the female producing seed.

Planting

Plant asparagus early in the spring, before growth occurs from the crown. Dig a hole about 15 cm (6 in.) deep. Place a small mound of earth in the hole; then set the plant on the mound so that the roots hang down and are evenly spread out in the hole. Cover the crown with 5 cm (2 in.) of topsoil. As the shoots elongate, add more and more soil until the hole is completely filled. The top of the crown (roots) should be 10 to 13 cm (4 to 5 in.) below the soil surface. The between-row spacing is 80 to 90 cm (2 1/2 to 3 ft), with an in-row spacing of 38 to 46 cm (15 to 18 in.).

Cultural Requirements

Asparagus plants respond well to a good moisture supply. They require 2.5 cm (1 in.) of water per week from May through October. Weed control is essential to eliminate any competition to the developing crowns. In the spring of the second and subsequent years after establishment, the top growth from the previous year, as well as about 5 cm (2 in.) of well-rotted manure should be tilled into the top 5 cm of soil.

Fertilizing is not recommended during the year of establishment. A commercial fertilizer with a high nitrogen content can be applied in the spring of subsequent years. The first number in the fertilizer formulation indicates nitrogen percentage, so choose a fertilizer with a high first number, such as 34-0-0. To side-band the fertilizer, dig a shallow trench about 5 cm (2 in.) deep and 15 cm (6 in.) to the side of the row. Apply commercial fertilizer at a rate of about 15 gm/m (1 lb/100 ft) of row. Then cover the trench with soil and apply water. Alternatively, the fertilizer can be broadcast at the same rate and watered in. Shallow tilling is required to prevent soil compaction and to control weeds.

Pests

Diseases and insects specific to asparagus are uncommon in this area and therefore pose few problems. However, in recent years asparagus rust has been reported in some locations in the province. The fungus causes tissue breakdown and premature foliage loss. The weakened plants are more susceptible to attack from other soil pathogens. Control can be achieved with spring and summer applications of a fungicide (Polyram or Zineb). The varieties Mary Washington and Viking have good resistance to asparagus rust.

Harvesting

The crown and root system must be allowed to develop before harvesting begins. The home gardener may be tempted to do some harvesting the first 2 years after planting. But bear in mind that removing spears will result in stress that will weaken the plants. Asparagus can be harvested for a 2-week period the third year after planting 2-year-old crowns. During the fourth and subsequent years, a full cutting season of 4 to 6 weeks is permissible.

It is not advisable to continue cutting well-established asparagus plants after the end of June in any year. During the cutting period, the plant draws on food reserves stored in the root system during the previous growing season. The top-growth must be allowed to develop after July 1 in order to replace the food stores in the fleshy roots. Excess harvesting in any year puts additional stress on the plant and may result in reduced yield the following year.

The cutting season usually begins between May 1 and May 15, depending on growing conditions. Under very favourable conditions, daily cuttings may be required, but every second day is usually sufficient. The shoots should be cut when they reach a height of approximately 5 cm (6 in.). They should be cut just below ground level. Take care not to damage new shoots still underground. The growth takes place near the tip of the shoot. Injuring this tip, even while it is below the soil surface, will usually stop the growth of the shoot and prevent its appearance. Cutting is best done with a knife that is pushed into the ground so that it severs the spear about 2 1/2 cm (1 in.) below ground.

Storage

Once harvested, asparagus spears deteriorate rapidly unless kept in a moist, cold atmosphere. An expected fresh storage life is about 1 week. For optimum quality, the spears should be eaten raw, steamed, canned or frozen as soon as possible after harvesting.

Winter Preparation

Watering should continue until late fall. The top growth can be left standing over winter; it acts as a snow trap to replenish moisture reserves in the soil. Because the crown area is well below the ground level, mulching to help prevent winterkill is generally not required. In open exposed areas, 10 cm (4 in.) of mulch applied in late fall will help to overwinter the asparagus plants.

Varieties

The most important varieties of asparagus recommended for Saskatchewan are Washington strains and Viking.

Potatoes: the Bitter and the Sweet and the Rotten

THE BITTER

Digging potatoes this weekend? If it's a bright sunny day and the temperature is near freezing, don't leave your spuds sitting in the sun for any length of time in the process of harvesting them. Have a tarp or old blanket handy to throw over them once they are dug. No, it's not that they'll "take a chill". It's the development of "glycoalkaloids" you should be worried about.

These substances (pronounced gly-co-al-ka-lloyds) are nitrogen compounds, mainly solanine, which in high concentrations are poisonous. In small amounts they are a normal constituent of potatoes and give them their characteristic flavor. They may also help to protect plants from insects.

As little as 1/2 hour of sunlight during harvest or storage exposure can produce enough glycoalkaloids to cause the bitter taste. If above-normal amounts are present, they will cause a burning, persistent irritation at the sides of the tongue and the back of the mouth when eaten - sort of like eating hot peppers!

Illness due to consumption of glycoalkaloids is highly unusual and is likely to occur only under the conditions of near famine - when individuals are consuming large quantities of bitter potatoes and very few others foods such as Russet Burbank (Netted Gem) or Kennebec.

The development of glycoalkaloids if often assoicated with greening. Some varieties green more readily than others. The slight greening of tubers exposed to fluorescent light in retail stores does not necessarily indicate high glycoalkaloid levels. Some varieties, such as Russett Burbank (Netted Gem) and Kennebec are more susceptible to the development of glycoalkaloids then others.

If your potatoes do show signs of greening, or have a bitter taste, remove and discard those portions affected. The glycoalkaoloids are not destroyed by cooking.

Preventing Bitterness

- keep tubers well covered with soil during the growing period

- avoid harvesting potatoes or leaving them in the field to dry on a clear, sunny day when the temperature is near freezing or may drop to near freezing.

- discard sunburned tubers

- store potatoes in the dark at temperatures between 40 and 50F (4.4 and 10C)

THE SWEET At the other end of spectrum, sweetness in potatoes can be a problem after a period of cold storage in late winter. The sweet taste is due to the presence of sugars which develop when the potatoes are stored at too low a temperature. It is recommended that they be stored between 4.4 and 10C. Temperatures between 3C and freezing cause the potato to convert its starch to sugar. While sweet-tasting potatoes are perfectly edible, the taste may not appeal to everyone. Some varieties will change sugars back to starch if stored at room temperature for several weeks.

THE ROTTEN

The two comon types of rots that affect potatoes in storage are bacterial soft rot and dry rot.

Bacterial soft rot is a soil-borne. infection that occurs through wounds or bruises to the potatoes skin, usually in the process of harvesting the tubers. Symptoms include sunken areas followed by a rotten, cream-colored ooze which later darkens and becomes foul smelling. Bacterial soft rot is common on either frost-damaged or wet potatoes which are put into storage.

Dry rot is a fungus problem which also infects tubers through wounds or bruises. There is a visible shrinking and darkening of part of the tuber. A cavity covered with a white, cottony mass may form inside the potato.

To prevent storage rots:

- avoid damaging or bruising potatoes during harvest

- if bruising does occur separate the damaged tubes and eat those first

- avoid digging potatoes when the soil is wet

- dry potatoes that are wet before storing

- "cure" potatoes prior to storing them at 12-16C (54-61F) for 7 to 10 days to promote wound healing.

Rhubarb

Rhubarb is an indispensable perennial vegetable in probably most Saskatchewan gardens. Shoots of this plant appear early in the season, when fresh vegetables are most welcome. It is a good source of vitamin C and iron, and is widely used in many desserts, jams and other preparations.

The leaves of rhubarb contain a high concentration of oxalic acid salts. The salts can be very toxic, so rhubarb leaves should never be consumed by humans or fed to animals. The leaves provide a good source of organic matter in a compost pile. The edible portion of the plant is the leaf stalk (petiole), which contains very low concentrations of oxalates. A high calcium intake should be maintained when rhubarb is being consumed in large quantities.

Soil Preparation

The ideal soil for a rhubarb patch is a clay loam. As with asparagus, the soil should be prepared with large amounts of organic matter. Soil preparation for rhubarb is the same as for asparagus.

Propagation

Named varieties are propagated by division of the crown and root system. The plants to be divided are dug up in early spring, and the clumps are cut into sections so that each section has a portion of the crown and root system. The leaves arise from the crown. Each section should contain at least 2 or 3 buds, with a good section of root. The larger the crown, the more rapidly will the plant become established.

Eventually the clumps become large and the buds become crowded. This results in smaller leaf stalks and indicates that it is time to renew the patch. Though a patch will produce for 15 years or more, optimum yield comes from patches 10 years and younger. Division of the crown and root is best done in early spring just as growth starts.

Planting

The best time to plant rhubarb is in early spring as soon as the frost is out of the ground and before much growth has occurred. Dig a hole sufficiently large to accommodate the root and crown. Spread the roots out evenly and fill the hole in with a soil:peat moss mixture (equal parts by volume). The division should be planted so that the top of the crown is not more than 2.5 cm (1 in.) below the soil surface. Adequate watering is required during the year of establishment. The between-row spacing should be 1.5 to 1.8 m (5 - 6 ft.), with an in-row spacing of 91 to 120 cm (3 to 4 ft).

Cultural Requirements

Rhubarb plants respond well to moisture, although reliable yields can be obtained with minimal watering. Fertilizing is not recommended during the year of planting. Weed control is required to eliminate any competition to the developing crowns. Care should be exercised not to injure the leaves when tilling. In the spring of the second and subsequent years after planting, about 5 cm (2 in.) of well-rotted manure should be tilled into the top 5 cm of soil. Shallow tillage is essential so as to not injure the crown. In the spring an application of commercial fertilizer is also beneficial. No more than 100 to 115 gm (approximately 1/4 cup) of a high-nitrogen fertilizer (e.g., 34-0-0) should be applied in a 90 cm (3 ft) circle, with the plant at the center. Shallow tillage will incorporate the fertilizer.

The plants should not be allowed to produce seed; when the plants devote energy to seed production, the development of leaf stalks is curtailed. Remove flower heads as soon as they appear in the spring.

Pests

Only one disease of importance is found on rhubarb in Western Canada. Red leaf disease of rhubarb commonly attacks the roots and crown areas of the plant. The leaves of the affected plants become reddish and later wilt and shrivel. New leaves cease to appear, and all that remains of the plant above ground is a few dry leaves. In some plants this process is slow, while in others it is rapid. Examination of the parts below the ground reveals decay in varying amounts. With plants showing only reddening of the leaves, the roots may appear normal on the outside, but their centers will be found to have rotted away. Some rotting in the crown will also be evident. In more advanced stages, when the leaves become dry, the greater portion of the root and crown will be found in a decaying condition.

There is still no good measure of control for this disease. The causal agent is not known, and until it has been found, no definite control measures are likely to be formulated. Shallow planting and a generous moisture supply may help to reduce the incidence of this disease. Affected plants should be completely removed as soon as possible after they show signs of this disorder. It is also good practice not to place new plants in soil where diseased plants have grown.

Harvesting

Do not harvest during the year of planting and during the next year. As with asparagus, the root and crown must be allowed to grow in order to store energy reserves. Full harvest can begin the third year after planting. No more than two-thirds of the larger stalks should be removed at any one time.

In harvesting rhubarb, simply pull the stalks; this will usually cause them to separate from the crown. Alternatively, you may cut the stalks at ground level. Harvesting usually begins in late May and continues until July. Under most conditions, harvesting should cease at the end of July to allow the food reserves to build up again in the roots and crown.

Winter Preparation

Watering rhubarb should continue until late fall. Watering requirements are the same as those for asparagus. Mulching to prevent winter injury is generally not required, since the crown is below ground level. A few inches About 5 cm (2 in.) of organic matter can be placed over the row in late fall, then tilled lightly into the soil in early spring. Dead leaves should be removed in early spring.

Varieties

Both red- and green-stalked varieties are available. Although the green varieties are more productive, the red varieties are preferred by most people. Macdonald is probably the most common variety available, but Valentine, Ruby, Canada Red and Sunrise are also acceptable.

Potatoes: the Bitter and the Sweet and the Rotten

Jackie Bantle

Last Week's article dealt with establishing your tomato plants. Once they are out in the garden, tomatoes require relatively little extra care. Like the majority of plants in our gardens, they will benefit form an even moisture supply without drastic fluctuations of soil moisture. Whether your soil is sandy or a heavy clay, a deeply-worked soil to which organic matter has been added will aid in maintaining uniform moisture. On a clay soil, organic matter permits easier water infiltration, while on a sandy soil organic matter absorbs and holds moisture, preventing rapid drying. For tomatoes, an even moisture supply is especially important because a tomato plant that is subject to frequent wet/dry cycles often produces a large number of tomatoes with the condition known as "blossom end rot." Blossom end rot is a soft rotting circle at the bottom of the fruit that is caused by fluctuating moisture conditions when that fruit was about the size of a pea. The best way to avoid this problem is simply to maintain even moisture.

Fertilizer

 Fertilizer for tomatoes is available in the pre-packaged forms usually sold in small colourful packages under names such as "tomato food." Such marketing strategies create the impression that the manufacturer has found the single perfect combination of nutrients that will assure you of a bountiful tomato harvest no matter what. Probably all you really need to know when fertilizing your tomatoes is that you don't want to be giving the plants an excessively high level of nitrogen in relation to the level of phosphorus. If the middle of the three numbers on your fertilizer bag is higher than the first, that fertilizer contains more phosphorus than nitrogen, and a handful of it dug into the ground near the roots of your tomato plants will probably be of benefit. The fertilizers to avoid for tomatoes and other flowering vegetables are those such as 34-0-0 which you might use on the lawn. If the first number is high and the second is low (in this case zero) you are supplying a high level of nitrogen and no phosphorous. This creates a mineral balance that favours development of lush green leaves but no flowers. While this fertilizer may give you the most impressive tomato plants on the block, these enormous plants will probably devote little energy to fruit production.

Growth Type

A tomato plant can be one of two types: either determinate, or indeterminate. A determinate plant has stems which reach a certain size, and then stop or "terminate" their growth, usually ending with a large floral cluster. Just above each leaf on these plants you commonly find a floral cluster. These types of tomatoes comprise the group we commonly call bush tomatoes. They tend to be popular on the prairies because they are among the earliest maturing.

An indeterminate plant has stems which continue to elongate throughout the life of the plant forming what we know as tomato vines. On such vines, side branches will arise from the point where a leaf joins the main stem, and flowers will arise some of these branches. Not all of these branches produce flowers, however, so large portions of the plant can sometimes be without fruit. To maximize fruit production, vine type tomatoes will usually require pruning and staking, while brush type plants will require no special attention.

Pruning and Staking

Pruning and staking your vine type tomatoes results in larger fruit that is held above the ground where it is less subject to rotting. Proper pruning also exposes more surface of the plant to sunlight improving growth. Because pruning will also result in some thinning of the fruit, the size and quality of fruit remaining is enhanced.

To stake a tomato, drive a 1-1.5 m stake into the ground beside the plant and loosely tie the main stem of the plant to the stake. As the plant grows, additional ties should be added to ensure that the tomato remains erect. In all cases, the tie should be loose enough that the stem is not constricted or cut. All non-flowering side shoots should be removed immediately after the plant is placed in the garden. When the first flower cluster is evident, allow the side shoot below that flower cluster to grow. Each week you should remove all side shoots that are not growing directly beneath a flower cluster.

Tomato cages are also recommended for both vine and bush type tomatoes. Cages for tomatoes usually consist of a wire cylinder about one meter high and 35 cm in diameter, made from mesh wire in 15 cm squares. If these are placed around the plants soon after they go into the garden, the cages will assure that the fruit stays above the ground. 

Harvesting the tomato crop

Harvesting tomatoes requires a gentle hand to remove the fruit without damaging the plant or unripe fruits that may be closely associated with the one you are picking. You must pick tomatoes at the right stage of maturity. Tomatoes will ripen naturally off the vine once they have reached the stage of maturity known as "hard green," but a tomato is considered to be mature only when it has reached the "breaker stage" of development. The breaker stage is indicated by the appearance of any pink or red colour on the fruit. At this point, all the chemical actions associated with ripening will proceed identically either on or off the plant, so the tomato that is picked at this point will be indistinguishable from one that has ripened fully on the vine. If a tomato has been picked prior to full ripeness it should be stored at normal room temperatures of about 15-20°C until ripe.

© 1995 Jackie Bantle

Tomato Production for Saskatchewan's Gardeners (Part 1)

Jackie Bantle

Nothing compares with the taste of your own fresh-picked tomato, so very few people consider a vegetable garden complete until at least a few tomato plants are included. The following are a few tips for successful tomato establishment.

Start with a Healthy Transplant

As warm-season crops, tomatoes require a long growing season to mature. The best crop therefore begins with healthy transplants. These transplants have traditionally either been started at home, or purchased from greenhouses in spring. When buying your transplants remember that the largest plants are not necessarily the best. A good transplant will be dark green in colour and not much more than 20 cm tall. The stem should be straight and stalky enough that the plants are very sturdy. The plant should have healthy white root tips, but should not be rootbound. This is easy to see if you pop a plant out of the cell pack. Also, you should resist the temptation to buy those plants that already have flowers or fruits developing. This promise of earlier tomatoes can be quite misleading, as larger plants with flowers and fruit will usually fall behind the smaller ones at establishment time. If your home-grown transplants have flowers, you are better off in the long run to remove them so the plants will not be diverting energy from root establishment to fruit production. Very often, home-grown tomato transplants also become somewhat taller than the ideal size. Such plants usually have a group of leaves at the top of a relatively bare stem. When planting tall transplants, you should dig them deep enough so that only the leafy tops are above ground. This will reduce the chance of the plants breaking in the wind, and since the below- ground portion of stem will quickly begin to develop roots, the stem can help in plant establishment.

Transplant shock and hardening off.

When a plant is taken from its cosy greenhouse environment and abruptly forced to face the harsh realities of the real world, it will often react by entering a condition known as transplant shock. If this happens, all growth stops for a period of one or more weeks, and in serious cases the plant dies. To avoid transplant shock, young plants should be "hardened off" for a week to ten days before the anticipated date of transplanting. In its simplest sense, hardening off can be thought of as a horticultural version of the philosophy: That which doesn't kill us makes us strong. Over a period of days, young plants are subjected to a greater and greater degree of stress, permitting them to adapt slowly to intense light, stronger wind and some drought. To start the process your plants should first be placed outside in a partially shaded location where they will receive good shelter-the east side of a house makes a good spot to start the process. Every few days the plants can be moved to a slightly more exposed location until they are spending the day in a nearly exposed site. During the process, the plants should be kept moist but not wet. This can be a bit tricky if you are leaving them out all day while you're at work because the little cell packs dry much more quickly outside than they do in the house. A slight drought by the end of each day is ideal, but if you are not sure they will make it until you get home, you are better off to give them a good watering each morning. More than one gardener has returned home to discover crisp little tomato plants by the back door, resulting in yet another trip to the greenhouse. Of course, throughout the process of hardening off, the plants should be brought inside if there is any danger of frost.

The Day of the Big Move.

After all danger of frost has passed transplants can be planted in the garden. Typically the May 24th weekend is the time for this, but with the cold spring of 1995, many people have opted to wait a week or more before transplanting.

The more thoroughly the soil has been worked prior to transplanting, the better the plants will do, and the easier the job will be. It cannot be strongly enough stressed that a small plant that is being pressed into a tiny hole chiselled into rock- hard soil has far less of a chance of survival than one that is being placed into loose, well-worked soil. When transplanting it is very important that the entire peat plug be is covered. If any part of the peat plug is left exposed, it will act as a wick, drawing moisture out of the ground and drying the roots. If you find that the plant has become root bound in the plug, you should gently break up the root ball. As distressing a thought as this may be for you, breaking up the tight circles of roots actually helps the plant establish because the broken roots will branch outward into the soil rather than continuing to circle in the established pattern. A light fertilizing with 20-20-20 is helpful soon after planting.

If possible, try to transplant on a cool cloudy day. The worst time to transplant is during the hottest part of a bright sunny day. At this time, the plant is most susceptible to drought stress, and leaves can quickly dry to the point of crispness. A few days of cool damp weather following transplanting doesn't hurt things at all, but whether it is cool or bright, you should provide frequent thorough waterings.

Many people find it useful to place old milk cartons or other protective surroundings around the plants. These serve two functions. Above ground, they protect the young plant from wind and bright sun immediately after transplanting. Below ground, they help to deflect the underground advances of cutworms that might be taking place just below the soil surface. Once the tops of the plants have emerged from these enclosures, the containers can be removed.

© 1995 Jackie Bantle

Vegetable Harvest Hints

The most anticipated moment for summer gardeners is harvesting the fruits of their labours. Most gardeners in their eager anticipation to feast harvest too early, or too late. The goal should be to harvest vegetables when quality is highest. After all, it is the quality of garden produce that sets it apart from store bought produce. Many vegetables not picked at the optimum time are stringy, woody, and tasteless, nullifying all the hard work and expense of growing the crop.

Here are a few guidelines to ensure that vegetables are harvested at the peak of perfection.

Beans: Green beans are ready to pick if the pods are smooth and evenly green. Snap beans are best if they snap easily when bent in half. Once snap bean pods start to turn yellow and the beans begin to corrugate, the pod the beans will be tough. Yellow bean cultivars should also be picked before they appear corrugated.

Beets: Beets may be harvested as soon as the root reaches 2.5 cm in diameter. Beets are their best at 5 cm in diameter, but over 7.5 cm they are tough and only suited to soups and processing. Only use the tender inner leaves for pot greens as the outer leaves are tough and stringy.

Broccoli: Cut broccoli when the individual flower buds are still in tight clusters. Once flower buds open, the broccoli has a strong undesirable flavour. The first harvest should consist of the central head and 12 cm of stem. A second crop can be harvested for several more weeks, but it will consist of side shoots and 12-16 cm of stem. Pick broccoli every 3-4 days so the crop does not get out of hand. Surplus broccoli can be frozen after blanching.

Brussels sprouts: Start picking the lower sprouts at 2.5-4 cm in size. The sprouts should be bright green and firm. If the weather stays cool, there many be upwards of 100 of the tiny cabbages per plant.

Cabbage: Begin harvesting cabbage head when they are small 10 cm in diameter and continue until head size reaches 15-25 cm. The heads should be firm at harvest. Waiting too late to harvest may result in split heads. Maturity may take 2-3 months, depending on the weather.

Carrots: Tiny sweet carrots can be harvested at 7.5-10 cm in length. Allow the remainder can be allowed to grow to about 2.5 cm in diameter. If carrots are allowed to reach 4 cm in diameter, they will be woody.

Cauliflower: For the best flavour, the head segments should be tightly packed, white or ivory in colour free of brown spots. When cauliflower heads start to form, leaves should be tied together at the top to form a teepee. This keeps the sun out and prevents the head from yellowing.

Corn: Harvesting corn at the right time is vital to the best flavour. Of all the vegetables, corn is most often harvested too late. The first thing to watch for is pollination which is indicated by clouds of pollen erupting when you walk through the corn patch. About 3 weeks later, the silk will turn brown. Maturity can be tested by peeling the husks back. Pop a kernel 5 cm from the tip the ear with a fingernail. If the fluid is watery, it is still too early pick; if the fluid is milky, the corn is at it best; if the fluid is the consistency of toothpaste the corn has gone starchy is only suited for creamed corn or used in chowders. The milky kernel stage only lasts for a few days.

After picking, cool corn cobs as quickly as possible, by plunging the ears into ice water and store in the refrigerator. Once cobs are picked, they immediately start turning sugars into starches, especially in warm temperatures.

Cucumbers: Cucumbers should be picked when green and about 7.5 cm long for sweet pickles, 15 cm for dills and 20 cm for slicing. Pick 4-5 times a week to encourage continuous production. Do not leave mature fruit on the vine. Once cucumbers turn yellow, a tough skin and tough seeds are formed.

Garlic/leeks/onions: Harvest green onions when the stem is a thick as a pencil. Leeks are harvested when the stem is 2-4 cm in diameter. Garlic is ready to be pulled when 1/3 of the top has died back.

Other onion types may be gathered as needed or when tops start to bend over and yellow. If onions are still actively growing by the beginning of September, bend the tops over to start a bulb curing process. A heavy frost will ruin onion bulbs. If onions do not are not curing on their own or if conditions are unfavourable for outdoor drying, spread bulbs out on the floor in a warm dry building with a forced flow of warm air. Garlic requires a curing period of about 20 days at 20°C (or 10-14 days at 27°C) with lots of air movement.

Lettuce: The outer leaves should be harvested before yellowing or browning occurs. If the stand is dense, entire plants may be harvested, giving the remaining plants more room to develop. Head lettuce should be picked firm. As semi-heading lettuce types do not form a firm centre, harvest as soon as a soft head forms.

Peas: Harvest bright green pods just before they round in cross section. Chinese and snow peas are picked when pods are still flat and about 4 - 6.5 cm long. Pods longer than 7 cm are too fibrous. Pick carefully so as not to break the vines. Do not leave overripe pods on the plants.

Bell peppers: Peppers may be harvested with a sharp knife when the fruit is dark green, regardless of size.

Potatoes: New potatoes may be dug up when the flowers form on the plant. Wait until the top growth starts to die back for fully grown tubers. If you want to store the tubers for a prolonged period of time it's advisable to wait until the crop matures. Mature tubers have a firm hard skin and are less susceptible to injuries and store well. It is best to harvest before the first killing frost. If the growing season is too short to mature the tubers naturally, the top of the plant may be killed to aid maturation. The skin will harden sufficiently if tubers are left 10-14 days in the soil.

Pumpkins: Wait until the fruit is a deep orange. The easiest method to determine ripens is to sink a fingernail into the rind. If the fingernail easily penetrates, the pumpkin is ripe enough for storage. By this time, the vines will usually be drying. If the pumpkin is not mature, leave it on the vine until after a light frost. However, if average daily temperatures are below 15°C growth is reduced or eliminated. If a heavy frost threatens, harvest and place the pumpkin in room temperature for a few weeks to harden the rind. Pumpkins may be stored at 10°C with 70 to 75 percent relative humidity.

Radishes: Thinning and eating may start when radishes are the size of marbles. Radishes may harvested up to 2.5 cm in diameter. Beyond that size radishes are pithy and strongly flavoured.

Squash/zucchini: Most people allow zucchini to become much too large. Harvest the common green zucchini when the fruit is only 15-25 cm in length. Yellow squash types should be harvested at 10-17 cm and patty pan (scallop types) when only 7-12 cm in diameter. Summer squash that grows too large has a hard skin and large inedible seeds. Spaghetti squash is harvested when a golden yellow colour and banana squash is picked when golden orange. Leave a few centimetres of stem when harvesting winter squash in late summer or fall. Winter squash skins should be hard enough to resist your fingernail. Frequent picking will encourage continuous production.

Tomatoes: For the most flavourful tomatoes, wait until they vine ripen to a uniform red colour. The full red colour develops 5 days after the first signs of pink show on the fruit. If frost is approaching and there is still green fruit on the plant, pick the tomatoes with 5 cm of stem attached or pull the entire plant. Store in a cool dark place, such as inside a brown paper bag and allow to ripen.

Vegetables

The long weekend in May is traditionally the time when Canada's gardens take off with a jump. Usually, the weekend serves as a guide as to when we can expect that the last spring frost has passed. Of course, there are no guarantees, and frosts can occur in June.

Vegetable crops such as radishes, spinach, peas, lettuce, onions, cabbage and turnips which prefer cool growing temperatures can normally be directly planted into the garden three weeks before the May long weekend. This will permit them to avoid some of the summertime heat. Rapid-maturing crops such as lettuce and radishes may be planted throughout the summer to allow a sustained harvest. Vegetables which are extremely sensitive to frost and low temperature should not be transplanted to the garden until the first week of June. Tomatoes, peppers and eggplant planted out before this date may be set back by cool nights even if there is no frost. Several products such as floating plastic row covers, hot caps or "Wall of Water" protectors can safeguard plants from a couple of degrees of frost extending the growing season by several weeks.

Whether you grow your own, or purchase them, transplants must be hardened off before being planted out. The process of hardening off takes about a week to ten days and gradually acclimatizes plants to the more stressful growing conditions of the garden. To harden off your transplants, they should be placed outdoors in a shady and somewhat protected spot and gradually moved to a brighter and more exposed location. Along the east side of a house is a good place to start, as morning sun is less intense than afternoon sun. After a week to ten days the young plants will have become accustomed to full sunlight and be ready for transplanting without suffering shock when being placed in the garden.

Plants should be well watered prior to transplanting, and kept moist for at least a week following transplanting. A mild fertilizer solution can also be applied at the time of planting.

Although an extensive array of seeds and transplants are available from seed companies and greenhouses, it is often best to use those cultivars that have been tested and shown to be productive for the prairies. The following is a list of vegetable cultivars that have proven successful in the University of Saskatchewan's vegetable cultivar trials.

Broccoli: `Early Dividend' (very early), `Arcadia,' `Emerald City,' `Excelsior,' `Patriot,' `Platini,' `Green Comet,' `Mariner.'

Brussels Sprouts: `Prince Marvel,' `Golfer,' `Oliver.'
A note for Brussels sprouts: transplants provide an increase in harvest of up to 30% over direct seeding.

 

Cabbages Early: `Balbro,' `Polar Green,' `Rocket.'
Mid-season: `Copenhagen Market,' `Multi Keeper.'
Late (storage): `Bartolo,' `Lennox,' `Ballhead.'
Red Cabbage: `Red Rookie,' `Regal Red.'

 

Carrots: `Narova,' `Nandro,' `Danvers 126,' `Karaman,' `Caro Best,' `A Plus.'

 

Cauliflower: `Serrano,' `Snow King,' `Snow Ball,' `Shasta,' `Incline.'

 

Corn Early: `Quickie,' `Lyric,' `Earlivee,' `Express.'
Mid-season: `BiHoney Nova,' `Amaize,' `Seneca,' `Northern Supersweet,'`Norgold.'

 

Cucumbers: Pickling `Carolina,' `Earlipik.'
Slicing: `Jazzy,' `Seedway,' `Sweet Slice.'

 

Onions: Cooking `Yula,' `Norstar,' `Sweet Sandwich.'
Spanish: `Bullring,' `Cima.'
Red: `Mars,' `Mercury,' `Tango.'

 

Peppers: Green `California Wonder,' `Marengo,' `Big Bertha,' `Maestro,' `Valencia,' `Estilo,' `Spanish Spice.'
Hot: `Garden Salad,' `Serrano Grand.'

 

Tomatoes: Bush `Blazer,' `Rocket,' `Swift,' `Roadside Red,' `Summerset VF,'`Blazer,' `Terrific VFN.'
Cherry: `Cherrio,' `Pixie Hybrid.'

 

Watermelon `Sweet Favorite,' `Summer Flavour,' `Gold Baby.'

Vegetables To Avoid

Each year seed companies promote new vegetable varieties. The "All-America selections" are well worth considering. They are new varieties that have been given awards for their superior characteristics. The selection trials for the awards are conducted in 27 locations in Canada, Mexico, and the United States. The vegetables are evaluated and selected for flavor, yield, appearance, texture, disease resistance, production and space efficiency, and nutrition. All new varieties are judges against existing standard ones.

Unfortunately, not all of the varieties promoted by in garden seed catalogues are up to the standards of the All-America selections. The so-called "novelty" varieties are vegetables that are unusual in respect to size, color, or shape. Many of these novelty varieties are virtually inedible and often of very poor quality. Although most seed companies include only a few novelty varieties in their listings, some companies specialize in them. In reading their catalogues, keep in mind the old adage: "If it's too good to be true, it probably isn't."

Novelties galore

Among the many novelties you will want to avoid are Jumbo Tom, a very large tomato, claimed to be a contender to beat the record for the world's heaviest tomato. The record stands at 61 pounds, 8 ounces. For several years it was a fad to grow large pumpkins such as Atlantic Giant. Now some seed companies are pushing a very small variety, Jack-Be-Little. You will also find red lettuce, white, bi-color, purple, red and blue varieties of corn. Then there's a zucchini with male flowers said to be edible. You can buy a recipe book with the package of seeds. Eat heartily!

Oldies but not goodies

Another trend in vegetable offerings is the growing number of so-called "heritage" or "antique" varieties. These are toted as varieties that were popular in days of yore and are somehow better for you than varieties of more recent origin. Many of these "good old" varieties are not up to standard, and some of them are no older than varieties commonly sold.

Warm Season Vegetables Go Undercover

Doug Waterer and Dave Schmitz

The growing season in most of Saskatchewan is just too short for many garden favourites. The first fall frost usually catches heat-loving crops such as cantaloupes, watermelons, tomatoes and peppers before they are fully ripe. Prairie gardeners have learned to increase their yields from these warm season crops by planting or transplanting early into sheltered areas and by selecting early maturing cultivars. Protective coverings such as hotcaps and rowcover systems also help these crops cope with the cold weather.

The Helpful Hotcap

For years, transparent hotcaps have been used to speed the growth of vegetables during the cool days of spring. These small covers produce a warm, sheltered, humid environment ideal for plant growth. Each plant grows in its own hotcap until warm weather arrives or the plant outgrows its protective cover. The hotcaps protect against light spring frosts, allowing early planting. Insects also find it difficult to locate the plants under the protective caps.

Rowcovers

Recently, innovative growers have begun covering one or more rows of vegetables with a single sheet of transparent material. This rowcover system provides all of the growth promoting advantages of hotcaps but is easier to install, covers a larger area at a lower price and may be used to protect both direct seeded as well as transplanted crops.

In tests conducted by the Horticulture Department at the University of Saskatchewan rowcovers have benefitted many vegetable crops under local growing conditions. Sweet corn planted under rowcovers emerged 3 days earlier and matured 10 days earlier than unprotected plants. Protected muskmelons yielded four times as many mature fruit by the first fall frost as plants grown without the covers. Rowcovers protected early plantings of bell peppers against several degrees of frost. These early plantings produced mature peppers by the first week in July, nearly a month ahead of non-protected plants. Rowcovers protected broccoli plantings against root maggots by preventing the adult insects from laying their eggs at the base of the young plants. Rowcovers also slowed moisture loss from the soil and the crop, which reduced the water required to grow the crop.

Tunnel Rowcovers - Rowcover systems are easily constructed from readily available materials. Clear 6' wide 2 mil polyethylene available from most hardware dealers works well. While the plastic is still on the roll, a series of 3/4" holes should be bored through the plastic about 8" apart in all directions. These holes provide ventilation for the covered crop. Once the crop is seeded or transplanted, hoops made of 6' lengths of No. 9 galvanized wire are placed over the row with about 6" of each end of the hoop inserted into the soil. The hoops should be about 3' wide and 18" tall with about 3' between each hoop. The plastic is then stretched over the hoops and all the edges are covered with soil to produce a small greenhouse over the developing crop. Rows should run parallel to the prevailing winds to reduce the chances of wind damage to the tunnels.

Floating Rowcovers - Recently, several new light weight, woven materials have been developed that may be applied directly over the crop without causing damage to the plants. Slack in the covers accommodates growth while the covers are in place. These "floating" rowcovers provide all of the benefits of the polyethylene tunnels without the expense and effort involved in constructing or maintaining the tunnels. growers may be able to purchase these floating rowcovers through seed catalogues or local garden supply stores.

Growing Undercover

Rowcovers are typically left in place for 4 or 5 weeks, by which time daytime air temperatures should be warm enough to produce good growth without the covers. If temperatures rise much above 30C, the covers must be removed or ventilated, otherwise the covered crop may scorch. The flowers of many vegetable crops are easily damaged by heat, resulting in delayed fruiting. Once cucumbers and melons begin to flower, the covers should be removed to allow insects to pollinate the crop.

The covers should be removed on a cool, cloudy day to reduce shock to the plant. One side of the covers may be opened a day or two ahead of time to speed acclimation of the crop. The rowcovers should be left to dry in the field, then they may be rolled or folded for storage. Most polyethylene and fabric rowcovers may be used for two or more seasons before they become too dirty or brittle for further use.

The tropical environment under the rowcovers speeds the growth of weeds as well as the crop. The covering makes hoeing difficult so many growers lay black plastic under the covers to control weed growth. Polyethylene covers tend to divert rain away from the crop and into the space between the rows. Growers just supply water to young plants under polyethylene tunnels until their roots grow into the wetted zone between the rows. Woven types of rowcovers have the advantage of allowing moisture to pass through to the crop.

Carrots

Tips for Germination

  •  
    • Carrots prefer to grow in a sandy, sandy loam or loam soil.  In heavy clay soils, grow carrots on raised beds of soil.
    • Ideal soil temperature for seed germination is 20˚C (seeds germinate in 7 days).  It will take 17 days for carrot seeds to germinate at a soil temperature of 10˚C.
    • Good soil contact and consistently moist but not wet soil is essential for good seed germination.  Some gardeners have been known to cover their newly seeded carrot rows with a layer or two of newspaper or a light board to help conserve the surface soil moisture.  These coverings must be monitored and removed as soon as seeds germinate to allow emerging seedlings to grow. 
    • Pelleted seed refers to seed that is covered with an inert clay material.  Pelleted seed is slightly larger in size than bare seed, making it easier to handle.  The clay material around the seed also helps to attract moisture during seed germination. 
    • Ideal carrot spacing is 1.5 – 2cm between plants and 30-50cm between rows.  Carrots can be thinned early in the season or throughout the season as you harvest.
    • Carrot seedlings can withstand a light frost up to -2˚C.
    • Life expectancy of carrot seed stored under favourable onditions (10-20˚C and 10% humidity) is only three years.   Seeds stored under less favourable conditions will show poor germination after just a single year of storage. 

The Growing Season

  • Carrots are sensitive to weed competition throughout the growing season – but the slow growing seedling stage is particularly prone to being overrun by weeds.
  • How to deal with weeds in carrots
    • Site selection – plant carrots in the area of the garden with fewest weeds and easy access for weeding
    • Only seed the carrots once the soil is warm – otherwise the weeds will be well established before the carrots even emerge.
    • Grow Danvers-type carrots as they are fast emerging and produce robust seedlings with a big top.  All of these factors make Danvers-type carrots better able to tolerate weed competition.
    • Remove weeds promptly and stay on top of them for the entire growing season.
  • Twisted and forked carrots usually result when space between carrots is limited or the soil is too hard for carrots to easily grow into a long, straight root.  Plant pelleted seed at recommended spacing or thin carrots during the season to final, optimal spacing.  Plant carrots on raised beds in heavy clay soils.  Grow shorter rooted carrots, i.e. danvers or nantes type.

Irrigation

  • Tender, newly germinated carrot shoots will be unable to emerge through dry, heavy, crusted soil.  Keep seeded rows of carrots moist to encourage good seed germination.  Consistent watering early in the season will promote shoot growth and help in the development of deep, straight taproots.  
  • Actively growing carrots prefer 2.5cm moisture/week in well drained soils.
  • Excessive soil moisture will promote root rot.

Harvesting

  • Carrots can be harvested at any time.  Young carrots are very tender but the best flavour takes time to develop.
  • Oversize and overmature carrots are prone to splitting and generally taste woody and dry.
  • Mature carrots with tops intact can be left in the soil as long as the soil remains unfrozen (-1˚C or warmer)
  • A light frost can help sweeten carrots and improve their storage quality.

Storage

  • Ideal storage conditions for carrots are 0˚C, 95-100% humidity.
  • Remove tops and excess soil before storage.  If you must wash carrots before storage, wash gently:  new wounds will encourage bacterial rots.
  • Do not store apples in the same location as carrots.  Ethylene from apples will cause bitter flavours in carrots.

Diseases

Aster yellows
Symptoms:  include reddening of some leaves, starting at the crown infected plants produce a mass of spindly pale new shoots that resemble a witches broom.  The roots of plants infected with aster yellows are excessively hairy and have poor flavour. 
Control:  The only control is prevention:  minimize the number of leaf hoppers by controlling weeds in and around the garden.  Avoid growing carrots near plants that attract leaf hoppers (ex. forage legumes like clover or alfalfa). Some cultivars appear to be partially tolerant of aster yellows.

Sclerotinia mould
Symptoms: White cottony mould or mycelium on the leaves near the crown is seen following extended periods of cool wet weather in late summer/fall.   Once harvested, the infection spreads from the crowns to engulf the entire carrot root in a white fuzzy fungal mass.   As the fungus matures it begins to form sclerotia (1-2cm long oval,hard, black resting bodies).   A secondary bacterial soft rot may follow the initial sclerotinia infection of stored carrots.
Control: Practise a minimum three year rotation of carrots with non-host crops in the garden (ex. Onion, beet, spinach, and corn).   A good rotation would be: Year 1 = carrots, year 2 = beets, year 3 = corn, year 4 = carrots)
Keep weeds to a minimum and provide adequate spacing between crops to ensure there is good air movement in the garden; this will help reduce relative humidity.   Also avoid over-fertilizing the carrots – as this will only encourage excessive top growth which interferes with air flow near the crown.  
Avoid watering late in the evening.
Plant carrots on raised beds.  Control excessive leaf and soil moisture as well as flooding.
Harvest when the carrots are cool –ie; less than 5˚C.   Grade out any obviously infected roots and trim the crowns tight to the root to minimize the amount of sclerotinia inoculum being introduced into the storage.     Cool to the final recommended storage temperature of 0˚C as quickly as possible.  Provide good air flow and carefully maintain  storage temperatures.   Inspect the carrots frequently and immediately grade out any carrots showing any sign of decay.

Bacterial soft rot and watery soft rot
Symptoms: Fast growing watery soft rot most commonly seen in stored carrots.  Infection by bacteria soft rot requires some form of damage – such as  cuts made at harvest or too close trimming of the crown.    Soft rot can also be introduced by cleaning the carrots in infected wash water.   As soft rot affected carrots break down in storage they produce a foul smelling bacterial slime that oozes onto adjacent healthy roots. 
Control:  Handle the crop carefully to avoid root damage during harvest and storage.
Grow carrots in a sandy to loam soil and avoid excessive irrigation.
  Cool the carrots quickly after harvest.  Avoid surface moisture on the carrots, especially at warmer temperatures

Insects

Leaf hoppers spread aster yellows virus.  Leaf hoppers overwinter as eggs in the soil.
Prevention:  Control weeds and avoid growing carrots near plants that attract leaf hoppers (ex. forage legumes such as clover or alfalfa)
Keeping the carrots covered with a row cover may provide some protection against the leaf hoppers.

Vegetable Container Gardening

How to Grow Your Own Vegetables in Pots

Many urban dwellers believe that they lack the space or proper environment to grow a successful vegetable garden.  Just because you live in an apartment or condo; or your tiny backyard is rather shady, that doesn’t mean you can’t enjoy vegetable gardening.  Growing vegetables in containers can provide the best growing environment possible for your garden veggies without you having to relocate, amend the soil or cut down beautiful shade trees. 

Choosing your container

Any container that can hold moist soil and provide drainage for excess water is a possibility.  Containers must be free of contaminants and be food safe.  Depending on your budget, containers can be imported colorful clay pots or as simple as the old wooden apple crate grandma has in her shed.  Plastic or burlap bags filled with soil have even been good containers for a potato plant: at the end of the season, simply dump out the bag and harvest potatoes. 

The key to growing vegetables in pots is to provide a large enough pot for the vegetable being grown.  A bunch of radishes can be seeded into a 15cm diameter dish that is only 5-8cm deep.  However, this same dish would never sustain a larger plant like a tomato or zucchini or a root plant like a carrot.

What vegetables can be grown in pots?

Any annual vegetable that can be grown in a garden can also be grown in a pot.  Perennial vegetables like rhubarb, horseradish and Jerusalem artichokes will not overwinter in pots unless they are buried up to the pot rim in the ground or stored in a heated garage over the winter.  Some vegetables will be more challenging to grow than others. 

Some basic guidelines:   

-          Provide a large enough pot for the vegetable being grown. Pot size should be determined by considering recommended in-row and between-row plant spacings   Plants with larger plant spacing requirements should be planted in bigger containers whereas plants that grower closer together will survive and thrive in smaller containers (ex. spinach, leaf lettuce).  Eight litre (2 gallon) containers are recommended for large plants like tomatoes, zucchini, cabbage, broccoli or a corn. 

-          The growing media must be capable of holding water as well as draining.  Garden soil does not drain well in pots and is not recommended for pot grown vegetables.  Commercial media containing peat moss, vermiculite, perlite and some micronutrients are recommended.  Contact your local garden centre for available products. 

-          Adding compost or well rotted manure annually is a good idea for pot grown vegetables.  This will help provide a base line of nutrients as well as increased organic matter: the organic matter will help hold soil moisture and nutrients.    

-          Probably the most challenging issue with growing vegetables in pots is maintaining adequate water and fertility management.   Keep soil moist but not waterlogged.  Provide a weekly soluble fertilizer treatment of 20-20-20.  Mix according to label directions.  Monitoring water and nutrients is an essential daily task.

-          Pot location is important.  Locate pots in a location sunny warm location but remember that a hot, windy, dry location will require much more management than a sheltered location.   If all you have is semi shade or shade, don’t despair, vegetables like lettuce, spinach, mustard greens and beets will grow in shady areas. 

-          If possible, replace soil annually to minimize disease issues. 

Seeding and Planting

-          Follow the same guidelines for seeding and planting vegetables in pots as you would with seeding vegetables in the garden. Seeding depths and spacings do not change.  Because pots are above ground and the media in these pots tends to warm up faster than soil at ground level, pots can be seeded a little earlier than your ground garden. Remember that early emerging plants will need to be protected from spring frosts (temperatures at or below 0˚C) by moving pots indoors or covering with blankets.

-          To speed up seed germination, place a sheet of clear plastic over the rim of the pot to help warm up the soil.  Remove the plastic as soon as seedlings have emerged to avoid overheating seedlings.  Clear plastic pop bottles with the ends cut off can serve as mini-greenhouses to individual plants in pots. 

Intercropping and Companion Planting

-          Intercropping is a method of planting a smaller, fast-growing crop using the space between slower-growing larger vegetables.  The quick crop matures just as the slower crop begins to need more space.  Possible combinations include lettuce grown around cabbage or broccoli, radishes and green onions grown between carrots, or spinach growing around tomato. 

-          Companion planting refers to growing two different plants together that will provide benefits to one or both species of plants.  Flowers and/or herbs alongside vegetables in pots can be a good combination.  Companion flowers will attract pollinating insects which will also visit your bean, pea, tomato, pepper, zucchini or eggplant flowers.  Some companion plants discourage certain pests.  For example, marigolds have a distinct odor that tends to repel some aphid species.  Herbs like savory and thyme grown around faba beans or peas will deter black aphid infestations.  Chives or garlic alongside carrots will deter root fly. 

Plant Support

-          To make the most of your space in your vegetable pots, provide a structure for climbing and sprawling plants.  Something as simple as a bamboo stake or pruned tree branches can provide support for pea, pole bean or cucumber plants.  Cages or stakes for tomato plants are essential.  A cucumber pot braced up against a sunny trellised wall could provide ample cucumbers for a family of four for the season.  Cantaloup and smaller watermelon can be grown vertically as long as developing fruit are supported by a ‘sling’ made from expandable material such as women’s hosiery.

Be creative when growing vegetables in pots.  If you can imagine it, it is most likely possible.  Don’t be afraid to experiment and ....... have fun!

Growing Hydroponic Lettuce

Lettuce has excellent potential as a year-round indoor crop.  Lettuce grows rapidly, even in situations of relatively low light and temperatures.  Buttercrunch (aka Boston bibb or semi-head lettuce) type lettuce is particularly well-suited to indoor production as it produces compact high quality plants that can be harvested one leaf at a time or as an entire mature head.

Recirculating hydroponic systems allow very effective use of growing space and nutrients and are well suited to indoor production of high value crops such as lettuce. 

The University of Saskatchewan, working with the Greenhouse Growers Association of Saskatchewan has been conducting research into the best methods of growing buttercrunch lettuce in simple hydroponic production systems. 

 

Production in hydroponic systems started with 4 week old lettuce seedlings grown in rockwool cubes (2.5 cm * 2.5 cm * 3.0 cm deep).  The seedlings were grown at room temperature at moderate light levels and were fertilized weekly with 20-20-20 plus micronutrients at 100 ppm N.  After 4 weeks the lettuce seedlings were about 10 cm tall and had 6 true leaves (Fig. 1) – at which point they were large enough to be transplanting into the hydroponic production system.

The University of Saskatchewan has evaluated the performance of 26 different cultivars of buttercrunch type lettuce in hydroponic production.   So far, the best cultivars have been ...

Red Sails (Johnny’s Seeds) - produced excellent yields of large, red/green open-type heads.  Red Sails received the highest flavor rating of all cultivars tested.    

Optima (Osborne Seeds) - is a great looking and good tasting semi-head type lettuce

 

Lettuce grows well in either Floating Culture or Nutrient Film Hydroponic systems

 

Floating culture - Is the simplest production system.   Plants are grown on a cm thick sheet Styrofoam that floats on top of a nutrient solution held in a grow tank (aquarium, plastic tub etc)(see Fig. 2).  The 4 week old lettuce seedlings are inserted into holes cut through the Styrofoam block so that the roots are fully immersed in the nutrient solution, but the growing point remains above the nutrient solution.  The nutrient solution is kept aerated using a standard aquarium aeration system.   Spacing plants about 20 cm apart allows enough space for the lettuce to reach full size without wasting space. 

Nutrient film technique (NFT) - in NFT production, plants are grown in troughs and a thin film of nutrient solution is kept circulating down the troughs and past the root system.  The production troughs can be as simple as sections of circular or rectangular eaves trough (Fig. 3).  Trough lengths are kept relatively short (<5m) to minimize nutrient and oxygen gradients.  A hole saw is used to cut holes (5cm diameter) into the upper surface of each trough.  The holes are large enough to allow the 4 week old lettuce transplants in their rockwool plugs to be dropped easily to the bottom of the trough – with the leaves arranged so that they protruded through the hole in the top of the trough.  The holes were spaced 20cm apart and the troughs were also spaced 20 cm apart – this spacing provided each plant with enough room to reach full size, without wasting space.  The troughs were kept on a 2% slope so that the nutrient solution ran down the trough and over the root systems.  At the end of each trough the nutrient solution was gathered back into a capture tank and then pumped back to the top of the channels using a small circulating pump.  The nutrient solution was pumped through the production troughs at the rate of 1L/min.    Insufficient flow volumes result in depletion of nutrients and oxygen as the nutrient solution runs down each channel.  However, excessive high flow rates waste pumping capacity and may interfere with uptake of certain nutrients.  The 1L/min  flow rate was achieved by installing pressure compensated button-type emitters in the spaghetti tubes that supplied each grow channel.  These emitters are available locally from suppliers of irrigation equipment.  However, these emitters are easily plugged by plant debris or algae in the nutrient solution.  Installing a 100 mesh in-line filter just upstream of the emitters solved this plugging problem.  Four troughs operating at 1L/min could be run off a single circulating pump.  The nutrient solution in the capture tank was kept aerated using a small aquarium pump.

Crop and Nutrient Management

Successful hydroponic production depends on supplying the plants with an adequate, well-balanced nutrient supply.  Nutrient recommendations for hydroponic lettuce are presented in Table 1.   While it is possible to purchase pre-mixed complete nutrient formulations suited for general hydroponic production, creating your own nutrient solution will allow you to more closely meet the needs of your selected crop and in the long run will also be more cost effective. 

Hydrobuddy is a powerful, yet easy to use program designed to assist growers in preparing  nutrient solutions for hydroponic crop production.   Hydrobuddy is available as a free download and can be located by entering “Hydrobuddy” in your favorite search engine.  

Hydroponic lettuce grows best at pH of 6.0, whereas the water in Saskatoon has a pH of around 8.0.  Adding household white vinegar to the nutrient solution at the rate of 2-3 mL/L gave the required shift in pH.  The amount of nutrient solution to prepare depends on the size of your nutrient holding tank and the number and size of plants being grown.  About 1L of solution per plant is more than enough to meet the nutrient and water requirements of lettuce from transplanting through to maturity.

 

Crop Growth - Lettuce was ready to harvest 4-6 weeks after being transplanted into the hydroponic system – with the rate of growth and size of plants harvested being highly dependent on cultivar grown and the amount of light provided to the crop.  No problems with disease or insect pests have been observed.  Algae tend to build up in the systems as each crop progressed.  A thorough clean up of the entire production system at the end of each crop cycle was important for controlling algae and also prevented disease problems.   Clean up involves flushing out the system to remove any root material, scrubbing off any algae, then rinsing with a dilute (5%) solution of bleach, followed by a final rinse with clean water.       

Parts List

Seedling production 

-       Seed of a suitable variety                   -     Rockwool plugs or Jiffy pots to grow transplants

 

Floating Culture system

-       Sheet of 2 cm thick Styrofoam

-       Nutrient Holding Tank – should be at least 30 cm deep and hold 1 L of nutrient solution for each lettuce plant being grown

-       Aquarium aeration pump + air stone

 

NFT System

-       Grow troughs – standard rectangular or circular eaves troughs work well although the materials used have not been made to Food Grade Standards

-       Submersible water pump (10 L/min capacity is plenty)

-       2 cm diam PVC tube to carry nutrient solution from the reservoir to high end of the NFT system

-       100 mesh in-line filter – removes plant debris from the circulating nutrient solution

-       1 cm diam spaghetti tubing - to take the nutrient solution from the PVC supply hose to each production trough

-       0.5 to 1L/min pressure compensated emitters – regulate the rate of flow of nutrient solution into each trough

-       Nutrient holding tank – see description in floating culture system

-       Aquarium aeration pump and air stone