The Online Gardener's Handbook 2010
Chapter 4: Vegetables
Growing Tips

Table of Contents

  1. Introduction
  2. Planning
  3. Plant Hardiness
  4. Transplants
  5. Mulch
  6. Fertilizer
  7. Water
  8. Learn More

Introduction

Vegetables grown in a well managed home garden are fresher and more flavourful, cost less than their store bought counterparts, and are often of better nutritive value.

Planning

When planning your garden, consider first the types of vegetables you want to grow, as well as specific varieties and quantities. Planting dates, location, spacing and fertilizer needs may then be determined. For an average garden of 3 m by 7.5 m, 15 to 20 different vegetables can be grown.

Do not forget when planning your garden to plan for pests and pest management. Many of the cultural controls outlined in chapter 2 are preventative and should be considered at the planning stage. It is important to plan for pest management in advance, because if you wait until pests appear on your plants you will have limited pesticide options.

Choose vegetables and varieties your family prefers. Look for varieties that are resistant to the pests dominant in your area. Try to select plants and varieties that are well adapated to environmental conditions in your area, as these are likely to be more vigorous and better able to withstand attack by pests.

If space is limited, consider growing compact, high yielding plants such as peppers, eggplants and bush tomatoes. Growing plants vertically will also help. Cucumbers, peas, and pole beans, for example, can be trained to climb a trellis. Vine tomatoes can be staked. If yours is a large garden, you may instead wish to plant space-consuming plants such as squash and melons.

Plant Selection

Divide your garden into four sections, each of roughly the same size.

Section 1: Perennial crops

Example: asparagus, rhubarb, perennial herbs, strawberries and raspberries.

Section 2: Long-season crops

Example: sweet corn, eggplants, tomatoes, peppers, melons, leeks, onions, squash, potatoes and turnips (rutabaga). Because of its shading effect, you may wish to plant sweet corn elsewhere in your garden.

Section 3: Short-season crops

Example: beans, beets, carrots, lettuce, radish, spinach, Swiss chard, dill and peas. When planning this section, keep in mind that multiple crops can often be harvested in one season. Plant a second crop of beans after spinach, cress or lettuce are finished. Plant a second crop of carrots or beans after the first have been harvested.

Section 4: Cole crops

Example: early and late cabbage, turnips, kohlrabi (long-season crops) and collards, kale, Brussels sprouts, broccoli and cauliflower (short-season crops). It is rare that two generations of a cole crop can be grown in one season. Instead, cole crops are often grown sequentially: a short-season crop is planted first, and a long-season crop planted later in the summer.

Planting Dates

Vegetables are planted at different dates and some can be planted more than once a season.

Cool season crops can be seeded or planted outdoors in early spring, when the weather is still cool. Example: beets, Swiss chard, cabbage, collards, broccoli, brussels sprouts, lettuce, onions, parsley, peas, potatoes, radish, spinach, turnips and carrots.

Warm season crops must be seeded or planted outdoors after the soil has become warm. A temperature of 14-15°C in the top 10-12 cm is a good guideline. For recommended planting dates, see Table 9. Warm season crops can also be started indoors and transplanted when the soil is warm enough. Example: beans, beets, eggplant, sweet corn, cucumbers, okra, squash and melons. Beans and sweet corn, however, are not suitable for transplanting.

  • Long-season crops require two to four months before harvest.
  • Short-season crops require less than two months before harvest.
  • Perennial crops grow year after year without replanting.

Use this knowledge to organize the timing of your planting season. You can plant cabbages, lettuce, beans, beets, carrots, green onions and spinach twice in one season; radishes can be planted three times. Plant vegetables such as broccoli, cauliflower, multiplier onions, lettuce, radish, spinach, beans and sweet corn at different times in different areas to have a constant supply. Follow early broccoli with cauliflower, and peas with Brussels sprouts or late broccoli.

Location

There are several basic guidelines when both choosing the location of your garden and determining the site for each vegetable:

  • Locate your vegetable garden in an area that receives at least six hours of sunlight, preferably during the warmest part of the day. Do not plant in shaded areas near buildings or large trees.
  • Space rows according to crop and tilling equipment used. Cooking onions, green onions, radishes or carrots, for example, do not produce large plants or leaves. They can therefore be planted with a narrow row spacing of 30 cm. Beans, corn or tomatoes, however, should be planted in rows 90 cm apart. If the tilling is to be done with a hoe, you will most likely want to minimize tilling space and so will place rows as close together as possible. This is also true for those with a small garden plot. If, however, you plan to use a rototiller, then consider planting rows 80-90 cm apart.
  • Plant rows running north and south to take maximum advantage of the sunlight. Rows running east and west may be necessary in sloping land to avoid soil erosion.
  • Plant sweet corn at back of garden next to trellised cucumbers and tomatoes to minimize shade to rest of garden.
  • Mix short and long season crops together in same or alternate rows to maximize growing area. Example: Grow lettuce and radishes (fast growers) between rows of cabbage or tomatoes (slower growers).

Drainage

One of the most important factors in a successful garden is good soil drainage. Without it, plants fail to thrive because their roots are not able to absorb the oxygen required for respiration.

When necessary, drainage can be improved by creating raised beds. To do so, prepare the soil as you normally would with organic matter and fertilizer. Dig up soil from paths placed about 1 m apart and throw this onto the middle, where the beds will be. The soil can be held in place by boards. Rake the surface smooth.

Plant Hardiness

Some vegetables fare better whatever the soil, planting and temperature conditions. Leaf lettuce will succeed under cooler and wetter conditions than will head lettuce. Corn and potatoes may kill to ground level if frosted, but will regrow - albeit with a later maturity date and lower yield - if they are in fertile soil and have storage material left in the seed.

Frosty Hardy

Frost hardy plants can resist a few degrees of frost (-2°C to -4°C) if the temperature change is not too sudden. Most of them require cool growing weather and germinate well at lower soil temperatures. They are often sown well ahead of frost-tender types.

Examples: broccoli, Brussels sprouts, cabbage, Chinese cabbage, cress, kohlrabi, leaf lettuce, onions and related crops, parsley, radish, rhubarb, peas, spinach, turnip, kale, parsnip.

Semi-Frost Hardy

Semi-frost hardy plants can tolerate temperatures of 0°C to -2°C for short periods of time, though injury may occur to top growth. Many of them are sown almost as early as frost hardy ones because they remain safely in the soil during cold periods before emerging above the ground. Most semi-frost hardy types can be sown fairly early in the season.

Examples: asparagus, beets, carrot, cauliflower, celery, Swiss chard, endive, head lettuce, herbs (many), potato.

Semi-Frost Tender

These plants will suffer injury to leaves and stems if exposed to temperatures of 0 to -1°C for more than several hours. Young shoot tips and buds, however, can usually withstand the cold.

Examples: snap bean, tomato, sweet corn.

Frost Tender

Frost tender plants are killed when exposed to temperatures of 0 C to -1 C for more than several hours. Leaves, stems, buds and shoots are easily blackened.

Examples: bean, corn, cucumber, eggplant, muskmelon, okra, peppers, pumpkin, squash and watermelon.

Transplants

Avid gardeners may start seeds indoors although transplants are best grown in a greenhouse, where ventilation, water, and light are easily controlled. Buying from a garden centre is most cost and time effective.

Consult Table 9 for the number of weeks required to grow transplants.

Media

Seeds are grown in a medium that must have good water drainage and adequate water holding capacity. It should also be free of herbicides, weeds, insects, and diseases. Pasteurized soil-based media or soil-free mixtures are recommended. Mixes containing unpasteurized garden soil are not recommended as diseases can develop.

It is possible to home-pasteurize your transplant medium. Place 10 cm of moist garden soil in cans or metal trays and bake in oven at 100°C or "warm" for one hour. Do not exceed this time and temperature. Clay pots and metal tools can be treated in the same way. Used plastic flats and pots should be scrubbed and sterilized by soaking in a solution of 1 part household bleach to 9 parts water. Peat moss should not be heated in the oven, as it will smoulder.

For a homemade soil-free mixture, combine the following:

  • 2 L horticultural vermiculite
  • 2 L horticultural perlite
  • 6 L shredded peat moss
  • 16 g (0-20-0) superphosphate
  • 32 g ground limestone
  • 24 g (33-0-0) ammonium nitrate or 64 g (5-10-5) fertilizer

Containers

Grow transplants in plastic pots or cell-pack containers (individual plastic vacuum-formed containers) to minimize transplant shock. Some root systems are more sensitive than others to transplanting. Cucurbits such as cucumbers, squashes, watermelons, and muskmelons should be planted in peat pellets or pressed peat pots that can be planted along with the vegetable. Peppers, eggplants, tomatoes and all cole crops can be transplanted bare-rooted.

Seeding

Sow seeds in moist -not waterlogged - medium following directions on seed packet. Most seeds will germinate at a depth of 0.5 cm. The larger the seed, the deeper it needs to be planted. Except for warm season cucurbits, sow seeds in rows, planting 8-10 seeds per 2.5 cm. Place the trays in plastic bags or cover them with a sheet of glass. When seedlings are 2-3 cm tall, transfer them to individual containers. Warm season cucurbits should be sown in containers. Plant 2-3 seeds per container, then cover with plastic bags or a sheet of glass. When seedlings emerge, thin them to one per container.

Lighting

Do not put seedling trays under artificial lights until seeds germinate. After that, remove bags or cover and place lights 10 cm above the seedlings. As they grow, adjust the lights 12-15 cm above leaves. Use horticultural fluorescent lamps, available at garden centres, to provide 12-14 hours of sunlight and temperatures of 20-22°C.

Transplants will grow under a combination of standard cool white and daylight fluorescent lamps. High light levels, however, remain a requirement to avoid stretching; this occurs when the plant grows long and spindly as it attempts to reach the available light source.

Watering

Keep soil moist with room temperature water, never allowing it to dry or the seedling to wilt. Do not leave pots sitting in a tray of water; too much water is as bad as not enough. Soil free media that forms a loose ball when compressed lightly in the palm of your hand is at the proper moisture level.

Preventing Diseases and Pests

The most common problem affecting transplants is damping-off, caused by fungi that attack seedlings at or just below the soil line. The stem may turn black and the seedlings will fall over.

Bacterial diseases of tomato, pepper and some cole crops can be transmitted through the seeds, but this is rare. Viral diseases are usually only a problem outdoors, where they are transmitted by insects. A few can also be transmitted by humans handling healthy plants after having touched infected ones.

Prevent pests and diseases by taking the following measures:

  • Use new containers and media every year.
  • Use sterilized tools and media.
  • Use resistant varieties.
  • Do not overwater.
  • Do not use contaminated plants.
  • Practice good sanitation by disposing of plant debris.
  • Do not allow the end of the hose to touch the ground of the greenhouse where it can pick up pathogens.

Hardening Off

Two weeks before transplanting, seedlings should be hardened off by placing them outside on nice days. This serves to toughen stems and leaves so that the plants are more tolerant of the elements. They are not as easily wind-tattered, sunburned or dried out, and can more easily withstand the move from the protected indoor environment. Hardening off also includes reducing the amount of water and fertilizer.

When placing transplants outside, do not put them directly in the sun at first, as the leaves will burn. They should also be placed against the house or in a similarly protected area. Coldframes, made of wood, metal, concrete or brick and covered by a hinged, removable panel of glass or clear plastic, can be used for long-term, outside storage.

Hardening off is particularly important when growing transplants at home, as these seedlings are often very tender.

Transplanting

Water seedlings thoroughly a few hours before transplanting, which is best performed in dull weather or in the evening when soil is moist. Plant most vegetables deeply (up to the first true leaves) to provide stability, and firmly press the soil around the root ball. This creates a slight depression at the base of the plant to trap water. Cover peat pots completely with soil or the root zone will dehydrate. If your garden is sloped, position your plants in the direction of the prevailing wind to prevent stem breakage. Fertilize with a starter solution of 15-30-15, 10-52-10, or 20-20-20 at the rate of 2 g per litre of water. For the first few days, shade the plants by placing cardboard or paper on their south side. Water them once or twice in the first week.

Row Covers

Row covers can be used to improve earliness of crops by increasing the above-ground temperature and protecting young transplants from wind damage. There are two basic types of row covers:

Floating covers are made of polypropylene or polyester and are laid on top of the transplants, in direct contact with them. These covers are well suited for vine crops and other low growing crops.

Mini-tunnels are made of white or clear polyethylene and are supported over the crop on wire hoops, with the edges of the cover buried. The plastic has perforations to allow ventilation.

Earliness of cucumbers, eggplants and melons is increased.

Heat can build up inside both types of covers and damage the plants. Temperatures should be monitored and covers removed or ventilated when the temperature exceeds 32-35°C.

Mulch

Mulch controls weeds and soil temperature, conserves moisture , reduces nutrient leaching, and prevents soil compaction and root damage from hoeing. There are two basic types of mulch: organic mulches that cool the soil, and plastic ones that warm it. The basic types are discussed below.

Plastic Mulches

Polyethylene film is the most effective mulch available. It accelerates crop maturity and reduces garden maintenance. It also allows later maturing vegetables to grow where the season is short. Tomatoes, peppers, eggplants, squashes, watermelons, muskmelons, cucumbers, beans, sweet corn, spinach, onions, and cabbages respond to polyethylene mulch.

There are three types of polyethylene mulch or film: clear, black, and brown. Brown and black films control weeds and keep the soil warm. Clear film, because it allows the passage of light, cannot control weeds. Brown film does not have to be removed after harvest, as do the others, because it breaks down by the time many crops are harvested. If mulch film is not available, green, blue, or black garbage bags can be split and used in small areas.

Roll the film over the prepared row and secure by digging 10-12 cm of soil under each side and anchoring the edges with it. Plant transplants or seeds through a hole punched with a sharp trowel or shovel. Water as usual.

Organic Mulches

There are many benefits to organic mulch: it contains plant nutrients; improves the soil's structure, making it easier to till; increases water-holding capacity; and aids in development of beneficial micro-organisms.

Organic mulches can be composted bark chips, cocoa beans, compost, ground corncobs, chopped cornstalks, grass clippings, leaves, manure, shredded newspaper, hay, sawdust, straw, and wood chips. Do not use evergreen needles, as their high acidity will lower the soil pH.

Wait until seeds have germinated and the garden has been weeded and lightly cultivated before applying organic mulches. Fine, heavy mulches such as sawdust and ground corncobs can be applied 5-8 cm thick; rough, light mulches such as straw and hay can be 8-15 cm thick. Remove mulches or incorporate them into the soil at the end of the season. If you have used a large quantity of organic mulch, add nitrogen fertilizer to the soil before digging it in.

Live Mulches and Green Manure Crop

Ryegrass, clover or oats can be seeded in between the rows as cover crops to control weeds and protect from soil erosion. At the end of the season, the cover crop can be incorporated into the soil as a green manure, adding organic matter. Seed cover crops in late July or after harvest and incorporate in the fall or early spring. Seed 1.5-2.5 kg rye or oats per 100 m of soil.

Cover crops can be used along with plastic mulches, seeded in between the rows. Mow them periodically.

Fertilizer

Commercial fertilizers are usually incorporated into the soil in early spring. However, many vegetables benefit from a second application given at specific times of plant development. Corn, cucumbers, squash, melons, broccoli, and cabbage respond to a further application of 225 g ammonium nitrate (33-0-0) per 30 m of row, four to six weeks after planting. A second application of fertilizer should be applied to tomato and pepper only after the first flower cluster has set fruit, otherwise the plants become too vegetative and fruit is late in setting, resulting in a very poor yield.

For a more detailed discussion of fertilizers, see Chapter 4.

Water

Your vegetable garden will need about 2.5 cm rain every 10-15 days for optimum growth. This amount - roughly 33 L water per 1 m soil - allows water to penetrate the soil to about 15 cm and provide nutrients to the root system. If there is not enough rain to meet this need, you will have to supplement.

One heavy watering is better than frequent light waterings, as these encourage shallow rooting, putting plants at a disadvantage. Water in the morning, because wet leaves at night will encourage spread of disease. Sandy soils require more frequent waterings than heavier soil.

If you prefer to use an irrigation system, soaker hoses and trickle irrigation are suitable for the home garden. They can be placed on one side of the crop row or under the mulch and can be used at night with less risk of disease than when using sprinklers. Less water is also required because more goes directly to the roots.

To determine how long it will take for your irrigation system to provide 2.5 cm of water, place a can under the sprinkler or hose and time how long it takes for 2.5 cm to accumulate. Irrigate this length of time in the future.

Learn More

 


For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca
Author: OMAFRA Staff
Creation Date: 21 July 2005
Last Reviewed: 25 June 2010