Organic Vegetable Gardening
Introduction
Successful vegetable gardens are not accidental. They are the results
of planning, constant care, and the will to make things grow. Among the
many things a 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, harvested at the
best stage of maturity.
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.
The information in this publication should be beneficial to all
gardeners regardless of methods of culture used; however, it is primarily
intended to aid the organic gardener to employ workable methods acceptable
to him and compatible with the philosophy of "organic
gardening."
SOME EARLY PLANS
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.
Choosing a Location ? Select a plot of good, well-drained soil
near a water supply. It should be close to the home for convenience, but
should not be shaded by tall buildings or trees. Enclosing the garden spot
with a fence is usually profitable.
The Garden Design ? 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.
PLANTING GUIDE
Vegetables suited to Florida gardens, leading varieties, seed or plants
needed, planting distances and depths, best time for planting by areas,
hardiness, days to harvest and expected yields are shown in the Florida
Vegetable Gardening Guide (SP 103) .
SOIL PREPARATION
Since organic fertilizer and soil conditioning materials are slow working
in general, they should be mixed into the soil at least three weeks ahead
of planting and the soil thoroughly prepared for the seed or transplants.
Clumps of unrotted organic materials not only interfere with the seeding
operation, but may result in nutrient deficiency and possible soil-borne
diseases problems such as "damping-off" of young seedlings.
ORGANIC MATTER
A major basis for organic gardening is the use of abundant quantities of
organic material applied to the soil. Usually, it is in the form of animal
manures, plant manures, cover crops, compost, or mixed organic fertilizer.
Benefits of Adding
Organic Matter
- Improves tilth, condition, and structure of soil.
- Improves ability of soil to hold water.
- Improves ability of soil to hold nutrients.
- Improves "buffering" capacity of soil; that is, keeps soil
from "over-reacting".
- Supports the soil's microbiological activity (or the life of the
soil).
- Contributes nutrients, both minor and major.
- Releases nutrients slowly.
- Acids arising from the decomposition of the organic matter help to
convert insoluble natural additives such as ground rock into
plant-usable forms.
- Helps vegetables survive stress, as from nematodes.
- Helps dispose of organic waste products.
What
Happens to Organic Matter Applied to the Soil or Compost Pile?
Under suitable conditions, the organic matter is decomposed by
micro-organisms such as fungi, algae, bacteria, molds, and earthworms. In
the process, insoluble and unavailable (to plants) nutrients, such as
nitrogen, are gradually changed into simple usable products.
For example, nitrogen is converted from the unusable organic
forms to a usable inorganic form through the process called nitrification.
Thus, nitrification is the breakdown of protein (organic nitrogen) into
ammonia and then nitrate. Some of the organic matter becomes part of the
soil humus.
Proper Conditions For
Nitrification
First, materials containing nitrogen must be present. There is a great
variation in the amount of nitrogen the different organic materials
contain. Then certain soil or compost conditions are necessary:
- Proper soil acidity (pH) ?should be about 7.0; in acid situation
below 5.5 it ceases.
- Proper temperature of soil ? above 50°F.
- Good aeration ? (does not occur with wet, soggy soil or compost).
- Adequate lime for use by micro-organisms and to keep the soil from
being acid.
ANIMAL MANURES
Where animal manures are available, they are probably the best source of
fertilizer and organic matter for the organic gardener. Use manure which
has been aged for at least 30 days, or composted.
Manures vary greatly in their content of fertilizing nutrients. The
composition varies according to type, age, and condition of animal; the
kind of feed used; the age and degree of rotting of the manure; the
moisture content of the manure; and the kind and amount of litter or
bedding mixed in the manure. Table
1 shows average minimal amounts of nutrients to be expected. They may
be as high as 4.5% N; 2% P; and 2% K in some cases. Animal manures also
provide most of the micro-nutrients needed. Some manure products are
composted, rehydrated or mixed with plant litter to enhance their
fertility.
How Much to Apply Broadcast
Before Planting
Cow, horse, hog ? A minimum of 25 pounds per 100 square feet (about 5 tons
per acre) of garden soil. For best results, supplement each 25 pounds of
manure with 2 to 3 pounds of ground rock phosphate or raw bone meal. Use
up to 1 pound per square foot.
Poultry, sheep ? Apply at least 12 pounds per 100 square feet (about 3
tons per acre minimum) - or as much as 3 - 4 inches (20 tons per acre).
Other animals? rabbit, goat, and exotic grass eaters ? 10-12 pounds/100
sq ft. minimum, up to 100 lbs. per sq. ft.
After Planting (As a sidedressing) if needed
Cow, horse, hog ? Sidedress with up to 5 pounds per 100 square feet of
row. Poultry, sheep ? Use up to 3 pounds per 100 square
feet of row.
How to Apply
All Types ? Broadcast evenly over plot and spade, roto-till or otherwise
work into topsoil. Apply three or more weeks before planting. A small
amount may be mixed well in the planting hole; however, plant injury may
occur with 1 lb. or more placed in the hole.
How to Apply as a Sidedressing
All Types ? Scatter a band of manure down each side of the row. Place each
band at the edge of the root zone and work lightly into the soil surface.
For individual plants, open a furrow encircling the plant and fill with
manure, then cover.
If a mulch is present, rake it back at the edge of the root zone
in order to apply the band of manure, then re-cover with the mulch.
NOTE: Manure is not always a complete well-balanced fertilizer.
It is advantageous to broadcast a complete organic fertilizer (such as
Fertrell) or ground rock phosphate and potash in addition to the manures.
COMPOSTS
Acceptable manure-like organic fertilizer (artificial manure) may be
obtained through the process of composting. Simply put, compost is
made by alternating layers of organic materials, such as leaves and
kitchen table refuse, with manure, topsoil, lime, organic fertilizer,
water, and air, in such a manner that it decomposes, combines, and yields
artificial manure.
How is the Compost Pile Made?
The compost pile is made of convenient size, usually not less that
10 feet square (100 square feet) and 3 to 5 feet high. The top should be
left flat or with a slight depression in the center to catch rain or added
water. Too much water eliminates air and slows the decay process.
One way suggested in building the pile is to make a layer of leaves,
straw, grass clippings, and other organic materials 1 foot deep, wet down
and pack. Spread a layer of manure 4 to 6 inches deep over this layer of
wet material. Then spread up to 5 pounds of ground rock phosphate or 1
quart of raw bone meal per 100 square feet, and 1 pound of ground
limestone.
Instead of the rock phosphate and bone meal, you could use 5 pounds of
a complete organic fertilizer such as Fertrell per 100 square feet. Also,
a layer of topsoil is sometimes used.
Then continue to repeat the process until the pile has reached 3 to 5
feet high.
Compost will begin to heat after 2 or 3 days. Keep it moist, but not
too wet, and do not disturb for awhile.
After 3 to 4 weeks, fork it over, mixing the parts to obtain
uniformity. Fatty animal wastes tend to create bad odors, draw flies and
ants; so, try to avoid their use if this will be a problem.
Compost for the garden should be ready from 2 months to 1 year,
depending on the time of year, type of materials added, and skill of the
composter. When the compost is broken down into a homogenous mixture, and
no undecomposed leaves or other material may be seen, it is ready for use.
What Organic Materials Can Be Used in the Compost Pile
Most anything organic, but most popular materials are natural materials
such as straw, leaves, pine straw, grass clippings, shrub clippings,
garbage, fish scraps, water hyacinths, etc. A list of materials and what
each might contribute to the compost is given in Table
2 . In addition, certain of the materials listed as organic
fertilizers (for example, tobacco stems) could also be added.
Use of Compost in the Garden
Since compost is artificial manure, it should be used much as you would
manure.
Broadcast it over the entire garden three weeks or more before
planting. Or if you have only a small quantity of compost, it may be mixed
into the soil along each planting furrow or at each hill site. As a
minimum, apply it at the rate of about 25 pounds per 100 square feet, or
º pound per square foot. Larger amounts are even more beneficial, up to
200 lb/100 sq ft. (2 lb/sq ft.). Caution: If your compost is made from
mostly woody materials, it may temporarily deplete the nitrogen from the
soil and plants. Be sure to mix manure with it when applying.
NATURAL AND ORGANIC
FERTILIZERS
Natural and organic materials which yield plant nutrients upon
decomposition are often available for purchase either separately or in
combination. These materials may be applied to the garden separately or
combined, used in the compost pile, or mixed with manure.
Many of the more commonly available materials are listed
in Table 3 along with the nutrients which they
produce. These include both the organic materials derived from plants and
animals, plus the natural deposits of rocks and minerals.
Natural Deposits (Rocks, Sands, Shells, etc.)
Such naturally occurring materials are usually not easily obtained in
today's modern agriculture; however, where available they represent
sources of mainly potash, phosphorus, and lime (calcium and magnesium) for
organic gardeners.
Phosphorus ? Rock phosphates are natural deposits of phosphate
in combination with calcium. The material as dug from the earth is very
hard and yields its phosphorus very slowly. When finely ground and with
impurities removed, the powdery material is only slightly soluble in
water, but may be beneficial to plants in subsequent seasons following
application. The reaction of phosphate rock with acids from decaying
organic matter in the garden or compost tend to make the phosphorus
available to garden plants. Collodial phosphate is also available and
widely used.
Apply both phosphates at the rate of 2-5 pounds per 100 square feet of
garden soil.
Or, when applying manure or compost, mix at the rate of 2‡ pounds
phosphate per 25 pounds manure or compost.
Broadcast the material over the soil surface and work into the topsoil
at least three weeks before planting. Manure or other organic fertilizer
should be added at this time.
Since the materials are so slowly decomposed, sidedressings are seldom
beneficial.
Potash ? Potassium is widely distributed in nature, occurring in
rocks, soils, tissues of plants and animals, and water of seas and lakes.
In gardening practice, materials such as wood ashes, tobacco stems,
wool suint, seaweed, potash salts, greensand, and ground rock potash are
used alone, in combinations with other materials yielding other nutrients,
mixed with manure, or in compost piles.
Since the potash bearing materials vary so much in composition and rate
of decomposition, specific application rates must be determined for each
material and its combinations.
In general, ground rock potash at 5 pounds per 100 square feet may be
broadcast over the soil surface three weeks prior to planting and spaded
in. Langbeinite (Sul-Po-Mag) is used at 1 lb/100 sq ft.
Micro-nutrients ? An advantage for using organic materials as
fertilizers is that they contain many of the elements also needed by the
plants in addition to N, P, and K (for example, manganese in manure).
Besides the general amounts of micronutrients found in most organic
materials, certain ones are concentrated into such naturally occurring
materials as gypsum (calcium and sulfur), marl (calcium), dolomite
(Calcium and magnesium), limestone (calcium), basic slag (iron, calcium,
manganese and magnesium), and finely ground borosilicates.
Lime ? Reducing the acidity of the soil is the primary purpose
for using lime in the garden. However, liming materials also provide
nutrients for plant use. Calcium and magnesium are the two elements most
commonly provided by lime. Gypsum is used where more calcium is needed
without raising the pH.
Natural deposits of lime which are an organic gardener might use are
limestone, dolomite, shell, and marl. All these forms must be finely
ground to provide maximum benefit to the soil and plants. Dolomite is
preferred due to its ocntent of both calcium and magnesium.
Lime to sweeten the soil should be applied only when the needs have
been established by a reliable soil test. Under most Florida soil
conditions, applications of 2 to 5 pounds of finely ground dolomitic
limestone per 100 square feet usually will be sufficient except on very
acid soils.
Apply lime well in advance of the planting date, preferably 2 to 3
months before the garden is planted. Mix well with the soil and keep moist
for best reaction. Application closer to planting time is permissible, but
its benefits are delayed.
IRRIGATION
In irrigating the garden, it is advisable to thoroughly wet the soil once
a week unless sufficient rain falls. Thus, the soil will be moistened
throughout the root zone. Light sprinklings every day merely tend to wet
the surface and encourage shallow root growth. Drip or trickle irrigation
is encouraged as a method for conserving water.
Use of organic materials as soil conditioners and fertilizers tends to
improve the ability of the soil to retain moisture. Also, a good garden
mulch will conserve soil moisture. Please observe all local watering
regulations.
MULCHING
A mulch is any material, usually organic, which is placed on the soil surface
around the plants. Organic materials most commonly used for mulching
are leaves, grass clippings, pine straw, sawdust, and wood shavings.
Synthetic materials, mostly plastic sheeting, have been used quite often
in recent years.
Among the benefits of a mulch are (a) conserves soil moisture, (b)
conserves nutrients, (c) reduces soil erosion, (d) reduces crop loss due
to nematodes, (e) reduces weed growth, (f) provides barrier between fruit
and soil, thus reducing soil rot on fruit, and (g) moderates the soil
temperature.
Apply mulch before or after seeding or transplanting. Roll back the
mulch with a rake in order to wet the soil beneath when irrigating, for
best results.
At the end of the garden season, the mulch (except plastic) may be
removed and composted, or cut into the garden soil. Most mulch is woody
and should have manure or other rich organic fertilizer applied with it
when cutting into the soil.
WEED CONTROL
The primary purpose of cultivation is to control weeds. Weeds are easy to
control when they are small. Shallow cultivation and hoeing are advised in
order to reduce damage to the root system. A garden mulch, such as pine
straw, leaves, or other material, will help to keep weeds from growing if
the mulch is thick enough to exclude light.
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.
- Plant resistant varieties.
- Plant seed from disease-free plants.
- Select pest-free transplants.
- For cutworms, place a cardboard of tinfoil collar around plant stems
at ground level.
- Spade garden early so vegetation has time to rot before planting.
- Use a mulch; vegetables touching the soil may rot.
- Clean up crop refuse early.
- Plant as early in the spring as practical.
- Keep out weeds which harbor insects and diseases.
- Summer fallowing (clean cultivation) helps control nematodes.
- Summer flooding, where soil type permits, helps control nematodes.
- Hand-pick insects.
- Water in morning so plants are not wet at night.
- Dispose of severely diseased plants before they contaminate others.
- Some insects, like cabbage worms, may be killed by spraying with
natural preparations such as Bacillus thuringiensis.
- Rotate garden areas.
- Bake transplanting soil in oven at 160°F for 1 hour.
- Crotolaria spectabalis and marigolds, when planted as cover
crops, tend to reduce some kinds of nematodes. The use of marigolds to
repel nematodes from interplanted vegetables is not effective
control.
- 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.
- Insect traps, baited with phermone lures, work well in some
instances. Many of these have sticky adhesives to catch insects.
- Solar fumigation is effective in reducing some soil-borne problems
such as nematodes. Refer to "Nematology Plant Protection
Pointers", such as NPPP-17, for details.
ORGANIC GARDENING SUPPLIES
Suitable materials for growing vegetables the organic way are not always
easy to locate. The "conventional" garden supply centers carry
many products, especially seeds and equipment, which may be used by the
organic enthusiast. However, for the difficult-to-find items, the gardener
may have to order from specialty businesses dealing in organic gardening
supplies.
MORE INFORMATION
Additional information about organic gardening may be found in Fact
Sheet EES-327 , "Organic Fertilizers and Soil Amendments".
Tables
Back
Table 1.
| Table 1. Composition - Fresh Manure with
Normal Quantity of Water.
|
| Kind of Manure
|
% Water
|
% N
|
% P
|
% K
|
| Cow
|
86
|
.55
|
.15
|
.50
|
| Duck
|
61
|
1.10
|
1.45
|
.50
|
| Goose
|
67
|
1.10
|
.55
|
.50
|
| Hen
|
73
|
1.10
|
.90
|
.50
|
| Hog
|
87
|
.55
|
.30
|
.45
|
| Horse
|
80
|
.65
|
.25
|
.50
|
| Sheep
|
68
|
1.00
|
.75
|
.40
|
| Steer orfeed yard
|
75
|
.60
|
.35
|
.55
|
| Turkey
|
74
|
1.30
|
.70
|
.50
|
Back
Table 2.
| Table 2. Composition of Various Materials
Thrown into Compost Piles
|
| Compost Material
|
% N
|
% P
|
% K
|
| Banana Skins (ash)
|
---
|
3.25
|
41.76
|
| Cantaloupe rinds (ash)
|
---
|
9.77
|
12.21
|
| Castor Bean Pomace
|
5.00
|
2.00
|
1.00
|
| Cattail Reeds
|
2.00
|
.81
|
3.43
|
| Coffee Grounds
|
2.08
|
.32
|
.28
|
| Corncob ash
|
---
|
---
|
50.00
|
| Corn Stalks & leaves
|
.30
|
.13
|
.33
|
| Crabgrass, green
|
.66
|
.19
|
.71
|
| Eggs, rotten
|
2.25
|
.19
|
.15
|
| Feathers
|
15.30
|
---
|
---
|
| Fish scrap
|
2.00-7.50
|
1.50-6.00
|
---
|
| Grapefruit skins (ash)
|
---
|
3.58
|
30.60
|
| Oak Leaves
|
.80
|
.35
|
.15
|
| Orange culls
|
.20
|
.13
|
.21
|
| Pine needles
|
.46
|
.12
|
.03
|
| Ragweed
|
.76
|
.26
|
---
|
| Tea grounds
|
4.15
|
.62
|
.40
|
| Wood ashes
|
---
|
1.00
|
4.0-10.00
|
Back
Table 3.
|
Table 3. Average Plant Food Content of
Natural and Organic Ferilizer Materials
(Percentage on a
Dry-Weight Basis.)
|
| Organic Materials
|
% N
|
% P
|
% K
|
Availability
|
Acidity
|
| Fish Scrap
|
5.0
|
3.0
|
0
|
slowly
|
acid
|
| Fish Meal
|
10.0
|
4.0
|
0
|
slowly
|
acid
|
| Guano, Peru
|
13.0
|
8.0
|
2.0
|
moderately
|
acid
|
| Guano, Bat
|
10.0
|
4.0
|
2.0
|
moderately
|
acid
|
| Sewage Sludge
|
2.0-6.0
|
1.0-2.5
|
0.0-0.4
|
slowly
|
acid
|
| Dried Blood
|
12.0
|
1.5
|
0.8
|
mod. slow
|
acid
|
| Soybean Meal
|
7.0
|
1.2
|
1.5
|
slowly
|
v. sl. acid
|
| Tankage, Animal
|
9.0
|
10.0
|
15.5
|
slowly
|
acid
|
| Tankage, Garbage
|
2.5
|
1.5
|
1.5
|
very slowly
|
alkaline
|
| Tobacco Stems
|
1.5
|
0.5
|
5.0
|
slowly
|
alkaline
|
| Seaweed
|
1.0
|
---
|
4.0-10.0
|
slowly
|
---
|
| Bone Meal, Raw
|
3.5
|
22.0
|
---
|
slowly
|
alkaline
|
| Urea
|
45.0
|
---
|
---
|
quickly
|
acid
|
| Castor Pomace
|
6.0
|
1.2
|
0.5
|
slowly
|
acid
|
| Wood Ashes
|
---
|
2.0
|
4.0-10.0
|
quickly
|
alkaline
|
| Cocoa Shell Meal
|
2.5
|
1.0
|
2.5
|
slowly
|
neutral
|
| Cotton Seed Meal
|
6.0
|
2.5
|
1.5
|
slowly
|
acid
|
| Ground Rock Phosphate
|
---
|
33.0
|
---
|
very slowly
|
alkaline
|
| Green Sand
|
---
|
1.0
|
6.0
|
very slowly
|
---
|
| Basic Slag
|
---
|
8.0
|
---
|
quickly
|
alkaline
|
| Horn and Hoof Meal
|
12.0
|
2.0
|
---
|
---
|
---
|
| Milorganite
|
6.0
|
2.5
|
---
|
---
|
---
|
| Peat and Muck
|
1.5-3.0
|
0.25-0.5
|
0.5-.10
|
very slowly
|
acid
|
| Spent Mushroom Compost
|
2.0
|
.74
|
1.46
|
moderately
|
6.4
|
NOTE: Urea and calcium cyanamide are organic
compounds, but since they are synthetic,
it is doubtful that mostorganic gardeners would consider them acceptable.
|
Footnotes
This document is Circular 375, Florida Cooperative Extension Service,
Institute of Food and Agricultural Sciences, University of Florida
|
