The idea of organic gardening has been around for a long time, but it is being rediscovered by a new generation of gardeners who are concerned about the environment, their personal health, and the relation between the two. The organic gardening movement has also matured significantly over the last several decades. Many of the most dangerous materials are no longer available, and many new and effective products are now widely available.
Throughout history until the last century, there were few or no chemical fertilizers or pesticides used. Animal manures and composts were the only kinds of fertilizer available. In the early 20th century U.S., horse manure was the fertilizer of choice for most gardeners.
The arrival of the automobile, the decline of the horse (and the availability of horse manure), and the discovery by a German scientist that nitrogen, phosphorous, and potassium were the principal engines of plant growth ushered in an age of chemical fertilizers. The widespread use of DDT during World War II did the same for chemical pesticides.
The gardener who is committed to organic gardening does not simply boycott artificial chemical fertilizers and pesticides. He or she is committed to techniques that build healthy soil. Healthy soil, not chemicals, becomes the engine of plant growth. Good harvests, along with plants that resist disease and pests, are the byproducts of building healthy soil.
Soil-building methods have been used for centuries. Organic matter -- decomposed material that was once alive -- is returned and worked into the soil to feed microorganisms in the soil, which in turn feed plants. Compost, garbage, hay, straw, manure, and crops high in nitrogen that are grown just to be turned under are high on the list of natural fertilizers.
Rotating the location of crops is also a practice used in organic gardening to prevent disease and pests from lingering on in the soil to attack the next season's crops.
The individual gardener, working on a small scale, has little trouble adopting organic gardening techniques.
Organic gardeners are passionate composters -- creating small back yard fertilizer factories to turn a wide variety of waste plant materials into crumbly brown soil food.
Nutrients found in pulverized rock powders -- calcium, phosphorous, and potash -- are also important in organic gardening. Other fertilizers are byproducts of the poultry, meat, or other industries: bone meal, blood meal, poultry manure and wastes, whey, peanut, and cottonseed hulls are all valued as plant nutrients.
Chemical pesticides have no place in organic gardening. Organic gardeners have many insecticides at their disposal. Some are derived from plants, such as pyrethrum and neem. Some of the best insect killers are simply a refined kinds of soap or oil. And others more subtly pit one kind of organism against the pest. The bacterial insecticides Bacillus thuringensis ("Bt" for short), and milky spore are examples.
Often these pesticides are chosen for exactly the opposite reason that people choose other kinds of insecticides. Instead of being broad-spectrum and long-lasting, organic pesticides may attack just one type of insect and break down quickly after use. Organic gardeners know there are good insects as well as bad in the garden (bees, for example), and usually know enough about bugs to zap just the culprit and not the passer-by.
The reward of organic gardening is finding gardening success by working in harmony with nature and leaving a patch of Earth better than before.