Released by UF/IFAS
By Ed Thralls
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 answers as I don’t use chemicals in my garden, I use only natural products in my garden, organically grown vegetable are better that 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 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