When a group of backyard gardeners get together and talk about the organic practices they use in the vegetable gardens, you will often hear information that is confusing, such as I don’t use chemicals in my garden, I use only natural products in my garden, organically grown vegetable are better than conventionally grown vegetables, I only use organic seeds to grow my organic vegetables, there is an organic pesticide to control the pests in my garden, etc. Well, we will explore these questions as we try to provide you with unbiased, scientific research based answers.
The term “organic gardening” has been in use for about 80 years. The University of Florida has a publication titled “Organic Vegetable Gardening in Florida”: http://edis.ufl.edu/pdffiles/HS/HS121500.pdf. Along with the “Florida Vegetable Gardening Guide” http://edis.ifas.ufl.edu/pdffiles/VH/VH02100.pdf you are prepared to use organic practices in your backyard vegetable garden.
The term “organic” is often confusing when applied to gardening. It is most often used as a marketing tool such as garden supplies that host an “organic” label that means the product contains organic material or material that is high in carbon. Another example would be the “organic” label on food is a labeling term that indicates that the food has been produced through approved methods and not that the food is “organic.” For more information about the “USDA Certified Organic” label see: https://sfyl.ifas.ufl.edu/archive/hot_topics/sustainable_living/usda_organic_label.shtml
Growing vegetables with organic practices in the backyard vegetable garden does not mean that you will avoid pesticides (herbicides, fungicides, insecticides, etc). It means what if you need a pesticide, you will look for one that has been certified for use in the National Organic Program and has the Organic Material Review Institute (OMRI) label on it. Also, realize that organic pesticides are not safer than synthetic pesticides, especially if they are misused. Always read and follow the label instructions for best results and for your safety.
Fertilizers are still important. Plants do not do better with organic fertilizers than they do with synthetic fertilizers. The choice is yours. Organic fertilizers are not in a form that plants can readily take up. It requires soil microbes to convert the organic fertilizers into an inorganic form for plants to use. This will take a little while and it’s always best to add the organic fertilizers to the vegetable garden several weeks before you plant out vegetable transplants and seeds. An organic fertilizer refers to a soil amendment derived from natural sources that guarantees, at least, the minimum percentages of nitrogen, phosphate, and potash. Typical organic fertilizers include plant and animal by-products, rock powders, seaweed, inoculates, and conditioners.
Organic matter is composed of living organisms, fresh residues and decomposed residues. Organic matter improves the tilth (ability to support plant life) of the soil and prevents soil compaction and crusting. The amount of organic matter in soil of a thriving organic vegetable garden is about 3-5% by volume.
Just because it is organic matter, it doesn’t mean it is “organic.” There are many sources of organic matter, such as animal manures (should be composted at least 6 months), compost (is unregulated and may not be organic) and cover crops/green manures (best done during Central Florida summer months). The process of certifying organic matter for the organic vegetable program lacks standardization. Just because it came from a cow does not mean it is organic — how was the cow fed, cared for and what pesticides was it subjected to while it was producing manure? Composting animal manures (must be from animals that only eat plant material) stabilizes nitrogen and reduces viability of weed seeds.
Compost teas are often considered an organic practice. Little is known for sure about the uptake by plants of human pathogens from the soil. The science is still very new and much of it has taken place in a laboratory. If considering using compost tea, unless you are positive that the methods being used will minimize the presence of human pathogens, or not contribute to water pollution, it would be wise to save them, again, for nonedible plants and not in the backyard vegetable garden. See “The Myth of Compost Tea Revisited”: https://s3.wp.wsu.edu/uploads/sites/403/2015/03/compost-tea-2.pdf.
When applying animal manures to your vegetable garden, do not over apply as this can lead to leaching and polluting groundwater and lakes just like any other over applied fertilizer. About 1–2 two pounds per square foot is a good starting point. Then through the gardening season, 0.5–1 pound to maintain vegetable plants during the growing season.
Cover crops/green manures help build soil quality, add organic matter, reduce soil erosion, provide habitat for beneficial insects and spiders, provide nitrogen, suppress weeds and loosen the subsoil in the vegetable garden. It is best to grow these crops at the beginning of the rainy season or during winter if you do not plan to grow “cool season” crops at that time of year. Bean family (Legume) cover crops fix nitrogen on their plant roots for future plant use. Turn under the cover crops before they start flowering or flower head formation so the nitrogen on their roots will be available for the vegetable crops that will follow.
We have mentioned compost in a previous blog post. Compost acts as a soil conditioner to make gardening easier, provides a low analysis, slow release fertilizer and builds structure in the soil so the sandy particles will clump together and hold nutrients and water in the root zone longer. However, compost is not a substitute for fertilizer in a productive vegetable garden.
Prevention is a key strategy to disease management when applying organic practices in the backyard vegetable garden. Keep plants dry. Select vegetable varieties that are resistant to many of the diseases you may experience in your vegetable garden such as leaf spots, wilts, stunts, rusts and lesions. There are several organic fungicides to consider when trying to control diseases. Look for the OMRI label when you choose one. Crop rotation will decrease the buildup of disease organisms in the vegetable garden and is a simple matter of not growing crops from the same vegetable plant family in same place (at least 3 years).
Weed management doesn’t have to be difficult. You can pull them out of the ground, use a weeder or hoe to cut them from the ground, or choose one of several organic herbicides. Look for the OMRI label. The vinegar bottle in the food pantry is for making your food taste better and for food preservation. It has no purpose for weed control in the vegetable garden. Read the label and it will not have directions for application as a herbicide. It may burn the tops of weeds to the soil line but it does not kill the weed. Don’t waste your money.
Insect pests are a fact of life in the vegetable garden. Some insect damage may result in lower quality produce. You may experience lower yields because of insect damage. It is important to be able to identify which insects are pests and which are beneficial, and to recognize developmental stages and understand the seasonal life of each pest. It takes time and effort to protect produce from pests without synthetic insecticides. Avoid pest outbreaks by inspecting plants frequently (Scouting), and attract natural enemies including other insects, spiders and some mites. Plant native flowers near the garden to potentially attract beneficial insects.
Controlling insects using organic methods should combine several methods, such as handpicking and destroying pest insects on a regular basis, disposing of branches or plants that are heavily infested, and keeping your garden weed-free. The first step in pesticide usage should always be organic pesticides such as insecticidal soaps, sulfur dust and pyrethrum (OMRI approved). And remember that organic pesticides, derived from naturally occurring sources, are not safer than any other pesticide; they are meant to kill a pest so you should read and follow all label instructions.
Companion planting is not a mainstay of organic pest control. It is mistakenly believed that companion planting is the growing of different species of plants together for the benefit or one or both. However, there is little evidence to show that companion planting works. Monocultures create a pest paradise. Grow a diversity of plants where possible. Mixed planting can be effective and attractive in the vegetable garden. For more information see: http://chemung.cce.cornell.edu/resources/companion-planting.
When irrigating, the use of a rain barrel is thought to be an organic practice. Recent research by Rutgers University (https://njaes.rutgers.edu/fs1218/) demonstrated that water harvested from a rooftop is unsafe to use on a vegetable/herb garden. Rain barrels are great tools to reduce stormwater runoff and should be part of a sustainable landscape. However, use the harvested rainwater on ornamental plants, potted plants, for cleaning garden tools, or adding moisture to the compost pile, but keep the water in the rain barrel out of the vegetable garden. It may introduce e. coli or salmonella bacteria (human pathogens) into your food.
Home remedies employ certain common household items for pest management in the not-so-organic garden. Home remedies may or may not have actual pesticidal properties and many are used as a result of tradition or habit. None of these highly logical and intellectually appealing solutions has ever worked for me. If you still disagree with me and want to continue to use your home remedies for pest management, test each concoction on a small portion of a plant to make sure there are no adverse effects before applying it to the entire plant.
Using organic methods in the backyard vegetable garden will improve the quality of your soil, provide sufficient moisture, reduce levels of pests and reduce the need for synthetic pesticides and fertilizers.