Organic
Vegetable Gardening
Successful vegetable gardens are not accidental.
They are the results of planning, care,
and the will to make things grow. Among
the many things an organic vegetable garden
may offer toward a satisfying experience
are fresh air, exercise, sunshine, knowledge,
supplemental income, mental therapy, and
fresh food, rich in vitamins and minerals,
and land but not least: improved health.
Organic gardening differs from "conventional"
gardening mainly in the areas of fertilization
and pest control. The organic gardener
prefers to use natural and organic materials
and methods, and avoids using practices
and synthetic chemicals that may be detrimental
to his health or environment.
Garden Planning
The size of your garden will determine,
in part, many aspects of your garden plan.
Large gardens where tractors will be used
can be worked more easily with long rows;
small gardens may be worked more easily
in small raised beds with footpaths surrounding
them.
Consider the size of your family and
the amount of produce to be canned, frozen,
stored or sold, as well as that used fresh.
Don't underestimate the work involved
in organic gardening.
The garden should have a southern exposure
(south side of your home) or be in an
open area if at all possible. There should
be a minimum of six hours of direct sunlight
at the chosen location. A well-drained
site or raised
bed garden is ideal. Poor drainage
may be improved by regrading, digging
ditches, installing a tile drain field,
or adding organic matter.
Many gardeners find it helpful to draw
out on paper the location of each row
and the crop or succession of crops to
be planted.
Nearby trees and shrubs may have extensive
root systems that may interfere with water
and nutrient uptake of plants at your
site. Locate the site to minimize or avoid
this problem. As a last resort, consider
removal of trees and shrubs that may interfere
with production.
There are many other things to consider
in planning your garden. Fertility requirements
vary with the crop, so heavy feeders and
light feeders may be grouped separately
to help manage fertilization. Long-season
crops such as eggplant, tomato, pepper,
and okra should be planted so they don't
interfere with replanting short-season
crops such as beans and cole crops. Tall-growing
crops such as pole beans, tomatoes, and
corn should be planted so they don't shade
shorter crops. You may not be able to
accommodate all of these recommendations
in your garden, but you should try to
accommodate as many as possible to help
insure a successful garden.
You should consider fencing the site
if you have a significant wild animal
population nearby. Deer, raccoons, and
rabbits, to name a few, may become problems.
Domestic animals such as dogs may also
become a problem because many like to
dig. Fences as high as 6 feet, an electric
fence, or some combination may be required
to control animals such as deer. Finally,
for convenience, a location near the house
is desirable.
An important part of garden planning
is record keeping. General information
about soil amendments used and weather
information (particularly rainfall and
first and last frost dates) can be useful,
especially when tracked from year to year.
Specific information about a particular
vegetable can also be helpful for future
planning.
Information such as variety selection,
planting date, days to harvest, disease,
and insect problems should be noted. This
data can help you determine which vegetables
and varieties are best for your location.
Watering, fertilizing, and any cultural
practices should also be recorded. This
helps in determining what should be done
in the garden from day to day.
Finally, keep track of what is grown
where in your garden. This information
will help with successive plantings and
crop rotation as noted elsewhere in this
article.
When to plant is also an important part
of garden planning. Vegetables can be
classed into two broad categories: warm-
and cool-season crops. Warm-season crops
can be further subdivided into tender
and very tender vegetables, and cool-season
crops can be subdivided into hardy and
half-hardy crops. Very tender crops cannot
stand any frost and will not do well under
cool nighttime temperatures (below 55°F).
Tender crops also don't like frost but
can stand cooler night temperatures. Hardy
cool-season vegetables can withstand frost
and can be grown during the winter in
all but the coldest northern parts of
Georgia. Half-hardy cool-season vegetables
can withstand cool temperatures and light
frosts, but hard freezes and heavy frost
can be detrimental.
Vegetable
Hardiness and Days to Maturity Chart
Crop |
Hardiness |
Days
to Maturity |
Asparagus
|
Perennial,
winter tolerant |
Second
Season |
Bean, bush |
Tender
|
50-60
|
Bean, pole |
Tender |
65-75
|
Bean,
lima |
Tender
|
65-75 |
Beet |
Half-hardy |
55-65
|
Broccoli
|
Hardy
|
60-80
|
Cabbage
|
Hardy
|
65-80
|
Cantaloupe
|
Very
tender |
80-90 |
Carrot
|
Half-hardy
|
70-80
|
Cauliflower |
Half-hardy
|
55-60
|
Collard
|
Hardy
|
55-70
|
Corn
|
Tender
|
80-100
|
Cucumber
|
Very
tender |
60-65
|
Eggplant
|
Very
tender |
75-90
|
Kale
|
Hardy
|
50-70
|
Lettuce
|
Half-hardy |
60-85
|
Mustard
|
Hardy
|
40-50
|
Okra
|
Very
tender |
55-60
|
Onion
|
Hardy |
100-120
|
Peas,
garden |
Hardy
|
60-80
|
Pepper
|
Very
tender |
65-80
|
Potato,
Irish |
Half-hardy |
70-90 |
Radish |
Hardy |
25-30
|
Southernpea
|
Tender |
60-70
|
Spinach
|
Hardy
|
40-45 |
Squash,
summer |
Very
tender |
50-55
|
Squash,
winter |
Tender
|
85-120
|
Sweet
potato |
Very
tender |
90-150
|
Tomato
|
Tender
|
70-85
|
Turnip
|
Hardy |
45-65
|
Watermelon
|
Very
tender |
80-90
|
Spacing
Chart
Plant |
Spacing |
Asparagus |
14" |
Bush Beans |
4" |
Pole Beans |
36" |
Beets |
4" |
Broccoli |
24" |
Brussel Sprouts
|
18" |
Cabbage |
24" |
Carrots |
2-4" |
Cauliflower |
15" |
Corn |
3" |
Cucumbers |
48" |
Eggplant |
24" |
Lettuce |
8-12" |
Okra |
12" |
Onions |
3" |
Peas |
3-6" |
Peppers |
24" |
Potatoes |
8" |
Pumpkins |
6-8" |
Radishes |
1-3" |
Spinach |
6" |
Squash |
36" |
Tomatoes |
36" |
Watermelons |
72" |
Irrigation
Growing a crop without irrigation is
possible, but your success is enhanced
with irrigation. Several different methods
of irrigation can be used, with overhead
and trickle/drip irrigation the most common.
Trickle/drip irrigation is the most water-use
efficient because water is delivered directly
to plant roots with a low volume soaker
hose, drip tape, or emitters.
Soil Preparation
Organic gardening requires a long-term
outlook with respect to soil preparation.
In fact, the key to successful organic
gardening is to feed the soil with organic
matter, which feeds the plant, rather
than to feed the plant with inorganic
fertilizer as in conventional production.
An ideal soil would have equal parts of
sand, silt and clay, and contain about
5 percent organic matter. Most mineral
soils in Georgia will have less than 2
percent organic matter and are rarely
ideal. However, with work, most soils
can be improved and made productive.
Because it takes a long-term outlook
to build a good soil, don't be disappointed
if your results are less than ideal the
first year or two. New sites should have
all plant matter removed or turned under.
Areas with Bermuda sods or other invasive
plants should have the plants removed
to the compost pile (see composting)
and the soil turned under to expose roots
and rhizomes to desiccation. In addition,
soil solarization (discussed further below)
can help control these hard-to-control
weeds.
Some soils may have hardpans, which are
impervious layers several inches under
the soil. These hardpans are often found
on old farmland or new home sites where
equipment has compacted the soil. In either
case, these hardpans must be broken up.
On clay soils this can be very difficult.
Conventional Garden
Soil Preparation - For
the vegetable garden soils should be turned
to 10 to 12 inches deep. One method is
to double dig the garden. Dig a trench
6 to 8 inches deep along one side of the
garden, placing the soil on the outside
edge of the garden. Then use a spade or
garden fork to loosen the soil 6 inches
deep at the bottom of the trench. Soil
adjacent to the trench on the inside edge
of the trench is moved to fill the existing
trench, creating a new trench in its place.
Again with a spade or garden fork, loosen
soil in the bottom of this trench to a
6-inch depth. Continue in this fashion
until the entire garden has been double
dug. The soil from the first trench can
then be moved into the last trench. This
method of garden preparation will leave
a deep turned soil but is very labor intensive.
Alternatives include use of equipment
such as tractor-mounted plows or a Rototiller
set to the deepest depth. Organic matter
should be added during this deep-turning
process. If you do not make
your own compost mushroom compost,
composted cow manure, and Clay Cutter
are available in bags or bulk.
Raised Bed Garden
Soil Preparation -
This is the type garden we recommend.
What
is a 'raised bed' garden?
The 'raised'
part means that the garden soil level
is higher than the surrounding soil, and
'bed' implies size small enough to work
without actually stepping on the bed.
A bed should be no wider than 4' but can
be as long as desired. The bed does not
have to be enclosed or framed, however
framing offers other opportunities. Raised
bed gardens are perfect where space is
limited.
Visit Planting
a Raised Bed Vegetable Garden for
details about this method.
In either method organic matter in soil
is important for two reasons. First, as
it breaks down, it releases nutrients
that crops can utilize, and second, it
improves the water- and nutrient-holding
capacity of the soil. The amount of organic
matter to add varies with the chosen material,
the type of soil, and weather conditions.
For most gardens where there is heavy
clay 500-1,000 pounds of organic matter
per 1,000 square feet is a recommended
rate - or 1/2 to 1 cubic yard per 1,000
square feet.
As an example, an acre of dry soil 6
inches deep weighs about 2 million pounds,
which means that 1,000 square feet of
soil to the same depth weighs approximately
46,000 pounds. If we wished to raise the
organic matter of this soil 1 percent,
we would have to add 460 pounds of organic
matter. The amount of material required
may actually be quite a bit more because
most organic sources have a high water
content, as much as 50 percent or more.
In addition, many have high ash (nonorganic
residues) content, as high as 25 percent
or more. Organic matter with 50 percent
water content and 25 percent ash would
require 1,840 pounds applied to 1,000
square feet to raise the organic fraction
of the soil 1 percent. This may be impractical
both in terms of obtaining the necessary
organic matter and the fact that organic
matter must be added each year to sustain
the increase. Low rates (200 pounds per
1,000 square feet) of organic matter can
have a noticeable improvement in soil
tilth. Additions of 500 to 1,000 pounds
of organic matter per 1,000 square feet
per year can have a beneficial effect
on soil tilth and plant growth.
Composting
Compost is an excellent source of organic
material for your garden. It has the added
benefit of reducing the amount of waste
your household generates. All organic
kitchen and garden waste except animal
products can be composted. Material such
as bones and animal scraps should be avoided
because they attract vermin, flies, and
scavenging animals. A convenient size
for a compost pile is 4 feet wide by 5
feet long by 5 feet high. A frame made
of pressure treated lumber can be built
to hold the compost, but this is not really
necessary. Begin the compost by adding
12 inches of organic matter (kitchen scraps,
yard waste, etc.). Then apply 1 to 2 pounds
of high-nitrogen organic fertilizer such
as dried blood, guano, or poultry manure.
Finally, add 2 inches of soil. Continue
building the compost pile in this layered
fashion as you generate organic matter.
The center of the pile should be concave
to hold rain water. The center of the
pile should begin to heat up within a
couple of weeks. The composting process
should be complete within two to three
months, depending on material and outside
temperature.
Large material such as tree limbs, corn
stalks, etc., should be chopped into smaller
pieces to facilitate decomposition. Some
materials, such as lawn clippings, will
decompose very rapidly; others will require
turning the compost pile (which aerates
the pile) and adding more high-nitrogen
organic fertilizer. This will restart
the heating and decomposition process.
Green Manures
Any crop grown on land with the intent
of turning it into the soil is called
a green manure. Generally, legumes and
various grasses are grown as green manure.
Turning under a crop can provide a number
of benefits, including increasing organic
matter of the soil, decreasing certain
disease problems, and increasing the nutrient
level in the soil. After the green manure
is turned under, it decomposes and adds
nutrients and organic matter to the soil.
When used as a green manure, grasses
and small grains can decrease the incidence
of nematodes. Nematodes are microscopic
worms that feed on certain plant roots,
weakening the plants.
Using various legume crops can increase
the amount of nitrogen in the soil. The
amount of nitrogen will depend on the
crop, the time of year, and when in the
crop cycle the plants are turned under.
Anywhere from 30 to 125 pounds of nitrogen
may be added to the soil when a legume
crop is turned under.
Soil Solarization
Difficult-to-control weeds and soilborne
pathogens may be controlled with soil
solarization. Soil solarization should,
however, be reserved for solving these
specific problems in your garden because
it can also kill beneficial microorganisms
and insects.
Soil solarization involves covering the
soil surface with clear plastic for four
weeks or longer. To begin with, all plant
material and crop residue, as is practical,
should be removed. The soil should be
turned to break up any clods of soil and
raked smooth. The area should be watered
thoroughly so the soil is saturated. The
area then should be covered with a plastic
sheet. The sheet can be secured along
the edges with soil or rocks. Soil solarization
works best when air temperatures are high
and sunlight is most intense during the
summer months. Soil solarization is not
effective during extended periods of cool
temperatures or overcast weather.
Starter Solutions
Starter solutions can help get transplants
and newly emerged seedlings off to a good
start. These starter solutions are often
referred to as manure teas. High phosphorus
is particularly important in these solutions
because it encourages root growth. A good
homemade solution consists of 3 pounds
of poultry manure plus 3 pounds of steamed
bone meal in 25 gallons of water. Stir
the mixture often over several days; then
strain off the liquid. Use one cup of
liquid for each transplant. Fresh manures
can contain harmful bacteria, so be sure
to wash up after handling.
Successive Planting
and Crop Rotation
Because of the relatively long growing
season in Georgia, it is possible to produce
more than one crop a year on the same
land. Planting a second or third crop
on the same land within the same growing
season is called successive cropping.
Crop rotation, on the other hand, refers
to planting different vegetables on the
same land from year to year. Related vegetables
should not be planted on the same land
in succession or rotation. For example,
squash should not be followed with a related
vegetable such as watermelon, cantaloupe,
or cucumber. This practice helps minimize
insect and disease problems and helps
maintain soil fertility. Table 3 lists
related vegetables.
Crop and Variety
Selection
One of the most important decisions an
organic grower makes is crop and variety
selection. Not all vegetables do well
in all locations. Vegetables commonly
grown in your area are your best bet for
success. Trial and error will also help
determine which vegetables are best suited
to your area. As you try different varieties,
keep records so that this information
can be used in planning subsequent years.
Climate, disease, and insect problems
will be important criteria when selecting
vegetable crops. It should be pointed
out, however, that one year's results
may not be enough to determine the success
of a particular vegetable. For example,
a mild winter may result in a greater
insect problem than one might expect the
following season. On the other hand, a
cold winter may result in sufficient suppression
of the insect to make for a successful
year.
Variety selection is another important
consideration when selecting crops to
be grown. When available, varieties with
disease and insect resistance are best.
Resistance, however, is seldom 100 percent,
and the plant may show some symptoms but
less severe symptoms than susceptible
varieties.
Varieties can be grouped into two broad
categories based on how they were developed.
F1 hybrids are developed from crossing
lines that have been inbred for several
generations. These varieties have advantages
of increased uniformity and, often, increased
yield compared with open-pollinated varieties.
Open-pollinated varieties are less expensive,
and popular open-pollinated varieties
will remain in the market for years. In
addition, these seed will remain true
to type from one year to the next. Most
older varieties are open-pollinated types.
Very old varieties are often referred
to as heirloom varieties, and many can
be dated to the previous century and beyond.
These varieties are often sources of unusual
colors, shapes, and flavors.
Several vegetables are reproduced vegetatively;
that is, from parts of the plant itself.
These would include things such as sweet
potatoes and Irish potatoes. To improve
your results with these crops, buy certified
slips for sweet potatoes and seed pieces
for Irish potatoes. The certification
process insures true-to-type, disease-free
material.
Mulching
Mulching serves several purposes in organic
production including reducing weed growth,
conserving soil moisture and nutrients,
regulating soil temperature, helping prevent
soil erosion, and reducing water splashing
on plants (which keeps them cleaner and
reduces the spread of disease).
An added benefit comes from organic mulch:
As it decomposes, it increases the amount
of organic matter in the soil. Almost
any organic matter can be used successfully
as mulch. This can include things such
as old hay, straw, leaves, sawdust, paper,
or bark. Avoid materials that may have
a lot of seed such as fresh-cut hay or
overgrown grass clippings. Fresh material,
particularly sawdust, can rob your soil
and thus your plants of nitrogen. In addition,
avoid organic material that may be contaminated
with toxic chemicals or herbicides because
these may damage your plants.
Mulches should not be applied too early
in the spring because this can delay soil
warming. Wait until the soil is 65°F
to a depth of 4 inches before applying.
Solid materials such as newspapers should
be weighted with soil to prevent them
from blowing away. Weed control with mulches
may require the continual addition of
new material to smother weeds as they
emerge. Keep all mulches 2 to 3 inches
back from the stems of plants.
Fertilization
You must have accurate information about
your soil to fertilize properly. First,
the pH of the soil is important in determining
nutrient availability to the crop. Optimum
pH for most vegetables is between 6.0
and 6.5. Irish potatoes are a notable
exception with a desired pH of 5.0 to
5.5. Soil testing is the only accurate
method of determining the soil pH. Such
tests will offer recommendations on the
amount of lime to apply if the soil pH
is too low. Approximately 1 ton of lime
is required to raise the pH of an acre
1 point. This is about 5 pounds per 100
square feet. The actual amount of lime
required, however, will vary based on
soil texture, the crop grown, and the
buffering capacity of the soil.
In order to determine proper fertilization,
it is important to know the nutrient status
of the soil, which a soil test will provide.
Insect and Disease
Control
INSECT AND DISEASE CONTROL
During periods when infestations of various
garden pests are high, control by natural
means becomes very difficult. However,
the following practices will help to reduce
losses without use of chemical pesticides.
- For cutworms, place a cardboard of
tinfoil collar around plant stems at
ground level.
- Plant as early in the spring as practical.
- Keep out weeds which harbor insects
and diseases.
- Water in morning so plants are not
wet at night.
- Some insects, like cabbage worms,
may be killed by spraying with natural
preparations such as Bacillus thuringiensis.
- A good garden mulch tends to reduce
damage caused by nematodes.Many organic
gardeners approve of and use sprays
and other preparations containing naturally
occurring materials. Diatomaceous Earth
comes from petrified sea life. Pyrethrin,
rotenone, and ryania are examples of
natural poisons from plant parts. These
give some control to some insects under
certain conditions.
- Natural predators should be encouraged
wherever possible; however, predators
raised in captivity, then released into
the garden area are usually ineffective.
- Insecticidal soaps, made from fatty
acids tend to work well for some insects
under average conditions.
- The best first-line method of reducing
insect and disease pressure is to use
resistant varieties when available.
A good example is VFN tomatoes, where
the VFN stands for Verticillium-, Fusarium-,
and nematode-resistant material.
- Keep the garden as free of diseases
as possible. Plants with disease symptoms
should be removed and destroyed. A properly
constructed compost pile, which should
heat up in the center, can control many
diseases.
- Keeping your plants dry will help
reduce disease pressure. Using trickle
irrigation rather than overhead will
reduce the amount of time plants remain
wet and also conserve water. Of course,
there's nothing we can do about the
rain.
- Crop rotation also can be an important
method of controlling some but not all
soilborne diseases. The proper crop
rotation can substantially reduce nematodes
in the soil but will do little to reduce
southern blight.
- Insect control begins with healthy
plants. Don't bring problems into your
garden - buy insect-free transplants.
Timing is also important. Insect populations
tend to increase as the season progresses,
so planting early can avoid many insect
problems. Encourage beneficial insects
to stay in your garden. This can be
as easy as nailing a horizontal board
to a fence to encourage wasps to build
a nest.
Sources:
The University of Georgia College of Agricultural
and Environmental Sciences
Cooperative Extension Service |