Organic Vegetable Gardening & Farming - Techniques Guide

In agriculture, the word organic means “food that is grown or raised without synthetic fertilizers or pesticides or hormones.” According to the USDA National Organic Standards Agency, organic farming:

• is an ecological production management system that promotes and enhances biodiversity, biological cycles and soil biological activities;
• based on minimal use of off-farm inputs and on management practices that restore, maintain or enhance ecological harmony;
• has the primary objective of optimizing the health and productivity of interdependent communities of soil, plant, animal and human life.

 

Organic Vegetable Gardening

As a component of organic farming, organic vegetable gardening promotes and enhances natural diversity and biological cycles in agriculture. Rather than relying on synthetic fertilizers and pesticides, organic gardening is based on making the garden self-sufficient and sustainable.

The National Organic Program (NOP), http://www.ams.usda.gov/AMSv1.0/NOP, defines organic standards. Farmers must be certified to claim their products are grown organically. A conventional farmer can become certified organic during a three year transition period.

During this period, organic practices need to be used but the product cannot be claimed as organic. Organic growers or gardeners with sales of less than $5,000 per year do not need to be certified but their practice must follow NOP standards and be subject to audit.

Most home gardeners grow vegetables naturally and don't sell produce so they don't have to strictly follow NOP standards if the word organic isn't used for their produce. For a product to be called organic, it must contain at least 95 percent USDA certified organic ingredients.

This guide focuses on organic vegetable gardening & farming techniques applicable to the home gardener or organic community. However, commercial organic vegetable growers may also find this information useful.

Transition to Organic Gardening

Producing vegetables organically is a long-term process that is carried out in stages rather than a single production practice adopted within a single growing season. Adopting organic production techniques involves a transition from conventional to organic gardening.

The first step in this transition is to improve and maintain soil fertility or quality. Healthy and fertile soil is the base of success
organic vegetable production.

Soil is a biologically active and dynamic resource, providing plants with mineral nutrients, water and oxygen. Organic matter — living organisms, fresh residue and decaying residue — is an essential ingredient in healthy, fertile soil. Organic matter increases soil fertility while preventing compaction and hardening of the soil. Soils that are low in organic matter often become crusted or covered after heavy rains, which prevents the infiltration of water and oxygen into the root system of vegetable crops.

Organic matter slows soil erosion and provides a favorable environment for earthworms and beneficial microorganisms. Carbon dioxide from decaying organic matter brings soil minerals into solution, making them available for growing plants. The target level of organic matter in healthy soil is 3 to 5 percent. Yield potential can increase by about 12 percent for every 1 percent increase in organic matter.

Organic fertilizer

The amount of fertilizer applied to vegetable crops depends on the type and characteristics of the soil (pH, organic matter and cation exchange capacity), previous planting history and nutrient uptake by vegetables.

For example, heavy vegetables like tomatoes can remove as much as 120 pounds of nitrogen per acre each year. Soil should be tested every two years to determine the total nutrients in the soil.

Organic Disease Management

Plant diseases can seriously stunt or kill vegetable crops. Disease often appears as leaf spot, wilt, stunting, rust or sores. The causative agent may be fungi, bacteria, viruses or mycoplasma, or a stressful environment. For example, many vegetable crops will wilt not only from too little water, but also from excess water in the root zone. The key to successful organic disease management is prevention. The following strategies can be used to prevent disease in vegetable crops.

Resistance or tolerance. Whenever possible, choose disease-resistant vegetable varieties. Disease resistance means that even if a plant does occasionally get a disease, it will not be seriously affected. Tolerance to a disease means that the plant usually catches the disease when it is present but is able to survive the infection. Seed packages usually include information on disease resistance of these varieties, especially for hybrid varieties (F1)

Disease free transplant. Many vegetables can be designated as transplants. Examine the transplant carefully for spots or sores on the stems or leaves. Remove some transplants from the planting container and examine the root system. Healthy roots are white or light in color, and show no signs of rotting or over-wrapping of fibrous roots around the root ball. Avoid buying plants that have
already bear fruit.

Site selection. Always choose well-drained soil for growing vegetables. Root rot and other soil-borne diseases thrive in wet soil. Low spots in the field are also pockets of high humidity in the plant canopy, creating a favorable environment for disease. Avoid planting near trees or buildings that can reduce air circulation or the intensity or duration of sunlight. Use raised beds to increase soil aeration and drainage whenever possible.

Crop rotation. Crop rotation is a long-established and successful agricultural practice. The continuous cultivation of plants in the same botanical family allows the accumulation of disease organisms. Vegetables that are in the same botanical family should not be grown in the same area for at least three years. For example, watermelon, cucumber, chayote, melon and pumpkin belong to the family Cucurbitaceae and are often attacked by the same disease organisms. The rotation of curcurbits with vegetables in the Solanaceae family such as peppers, tomatoes, eggplant or potatoes has the potential to reduce disease incidence

Spacing and training. Dense plantings can often increase susceptibility to disease. By increasing the distance between plants, air circulation and light intensity are increased, creating a less favorable environment for disease development. Always stake or cage the tomato plant so that the plant and fruit don't touch the ground. Remove suckers (lateral shoots) to knots under the first fruit bunches on tomato plants to increase air circulation and light exposure thereby reducing disease incidence.

Mulching. Organic mulch such as straw, straw, compost, newspaper or wood shavings will help prevent disease by reducing direct contact between soil and plants. The thickness of the mulch should be 4 to 6 inches. Many soil-borne diseases infect plants from soil that is exposed to rain on the lower leaves. Organic mulch usually lowers soil temperature. Thus, summer vegetables such as tomatoes and peppers should be mulched only after the soil has warmed. Plastic mulch can also be used by organic farmers. Plastic mulch comes in a variety of colors and is very effective at warming the soil. Black plastic is the most commonly used plastic mulch for spring and early summer vegetables in Missouri. Infrared emitting (IRT) plastic mulch allows certain wavelengths to penetrate the plastic, increasing soil temperature significantly more than black plastic mulch. Growers who wish to plant later in the summer can use white plastic to keep the soil cool. When plastic mulch is used, water must be supplied through an infusion hose or rain hose under the plastic.

Rogue infected plants. Root and destroy plants showing symptoms of severe disease to prevent spread to nearby plants. Virus-infected plants should be removed from the garden immediately.

Sanitation. To prevent the transfer of plant diseases from one growing season to the next, clean all planting trays and growing equipment such as tomato wooden stakes, planting trays and harvest containers. Most materials can be soaked in a hydrogen peroxide solution or steam sterilized. Plant residues in the garden should be cleaned and disposed of. Do not compost diseased plant residues. Remove weeds around the garden as they can host plant diseases.

Seed savings. Many diseases are seed-borne. Some organic gardeners save seeds of favorite varieties. When saving seeds, make sure the plants from which the seeds are harvested have no symptoms of disease. Do not save seeds from hybrid varieties as the plants from those seeds usually separate and thus produce mixed crops.

Organic pesticides. Organic fungicides for vegetables include copper (Bordeaux mixtures or sulfates), hydrogen peroxide, and sodium bicarbonate (baking soda). When using baking soda, gardeners need to watch for the buildup of sodium, which can be toxic to plants. High concentration (70 percent) of Neem oil can be used to kill powdery mildew spores. Biological fungicides, which are beneficial bacteria or fungi, are available to organic gardeners. Most organic fungicides are applied to prevent the development of a disease. The Organic Materials Review Institute (OMRI), http://www.omri.org, reviews and approves materials to be used in organic production and continually updates its lists of approved and disqualified organic materials. Organic growers should check the OMRI list or consult the certifier before applying any new chemical.

Protected crop culture. High tunnels, or hoop houses, are plastic-covered, solar greenhouses that lengthen the traditional growing season and protect the growing vegetable crop from rain, wind, hail and erratic tempera- tures. High tunnels also exclude many pests that routinel attack vegetable plants in the Midwest. Most diseases need free moisture to become activated. Diseases are less likely to develop in a high tunnel because drip irrigation is used and the plant canopy is kept dry.

Vegetable grafting. Grafted vegetables (tomato, watermelon, melon, cucumber, pepper and eggplant) usually have better resistance to soil-borne diseases, more vigor and higher yield than non-grafted ones. The advantages come from the rootstock. Growers who prefer growing heirloom varieties, have limited garden space, or produce vegetables in a high tunnel or greenhouse should consider this emerging technique.

Organic Insect Management

Organic pest management is based on preventing pest outbreaks rather than dealing with pests once they have a foothold in the garden. The following are some techniques that can be used to control insects organically:

Inspect plants. Monitor the garden as often as possible, especially the borders or outer rows. Physically remove any harmful insects found to prevent the population from spreading to adjacent plants.

Habitat for beneficial insects. Create a favorable environment for natural enemies of harmful insects. More than 100 families of insects, spiders and mites contain species that are natural enemies of harmful insects. Plant the edges of the garden with real flowers or plants such as clover or alfalfa to attract beneficial insects such as ladybugs.

Row covers. Row covers are lightweight spunbond fabrics that can be hung or draped over vegetables to protect them from invasive insects. Row covers are very effective in reducing damage by flea beetles and cucumber beetles. Applying row covers to parthenocarpic cucumbers, zucchinis or other vegetables that do not require fruit pollination can greatly reduce insect damage.

Trap crops. Plant less desirable plants near the garden to attract insects away from important vegetables in the garden. Destroy trap plants once they are infested with insects.

Resistant crops. Some varieties or types of vegetables are less attractive to insects. For example, County Fairb pickled cucumbers are much less attractive to cucumber beetles than most other cucumber varieties.

Planting date. Many vegetable insects will have peak populations throughout the growing season. Avoid high insect populations by adjusting the planting date. For example, sweet corn planted early will have far less infestation of corn earworms than corn planted late

Intercropping. Intercropping is the practice of growing two or more vegetables in the same area during the same growing season. Avoid planting large blocks of any vegetables in the garden. Mixing vegetables prevents the spread and buildup of harmful insects.

Keep plants healthy. Healthy plants are less attractive to insects, and if attacked, are better able to survive and produce marketable crops. This also applies to organic disease management.

Sanitation. Remove the plant after harvest to prevent it from becoming a reservoir for harmful insects.

Fall plowing. Plowing the vegetable garden after the fall harvest exposes bugs and insect eggs to birds or to drought during winter freezes and thaws.

Organic insecticides. Several organic insecticides are available for use by vegetable gardeners, including Bt (Bacillus thuringiensis), pyrethrum, rotenone, insecticidal soap, diatomaceous earth, neem and horticultural oils. Check the label and consult your certification body before using any insecticide.