The Online Gardener's Handbook
Chapter 4: Vegetables
Table of Contents
- Plant Hardiness
- Learn More
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.
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
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.
Divide your garden into four sections, each of roughly the same
Section 1: Perennial crops
Example: asparagus, rhubarb, perennial herbs, strawberries and
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
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.
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.
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
- 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).
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.
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.
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 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.
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 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.
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.
9 for the number of weeks required to grow transplants.
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
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
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.
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.
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.
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.
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,
Hardening off is particularly important when growing transplants
at home, as these seedlings are often very tender.
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 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 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.
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
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.
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
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.
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
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
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.