Organic horticulture is the science and art of growing fruits, vegetables, flowers, or ornamental plants by following the essential principles organic agriculture in soil building and conservation, pest management, and heritage-species preservation.
The Latin words hortus (garden plant) and cultura (culture) together form horticulture, classically defined as the culture or growing of garden plants. Horticulture is also sometimes defined simply as “agriculture minus the plough (or plow).” Instead of the plough, horticulture makes use of human labour and gardener’s cultivation tools, or of small machine tools like rotary tillers.
Mulches, cover crops, compost, manures, and ground-rock mineral supplements are soil-building mainstays. Through care and good soil condition, it is hoped that insect, fungal,or other problems that sometimes plague plants can be avoided. However, pheremone traps, insecticidal soap sprays, and other pest-control methods available to organic farmers are also sometimes utilized by organic horticulturists.
Horticulture involves five areas of study. These areas are floriculture (includes production and marketing of floral crops), landscape horticulture (includes production, marketing and maintenance of landscape plants), olericulture (includes production and marketing of vegetables), pomology (includes production and marketing of fruits), and postharvest physiology (involves maintaining quality and preventing spoilage of horticultural crops). All of these can be, and sometimes are, pursued according to the principles of organic cultivation.
Organic horticulture (or organic gardening) is based on knowledge and techniques gathered over thousands of years. In general terms, organic horticulture involves natural processes, often taking place over extended periods of time, and a holistic approach - while chemical-based horticulture focusses on immediate, isolated effects and reductionist strategies.
The central gardening activity of fertilization illustrates the differences. Organic horticulture relies heavily on the natural breakdown of organic matter, using techniques like green manure and composting, to replace nutrients taken from the soil by previous crops. This biological process, driven by microorganisms, allows the natural production of nutrients in the soil throughout the growing season, and is often referred to as "feeding the soil to feed the plant." In chemical horticulture, individual nutrients, like nitrogen, are synthesized in a more or less pure form that plants can use immediately, and applied on a man-made schedule. Each nutrient is defined and addressed separately.
The central horticulture activity of fertilization illustrates the differences from chemical-oriented horticulture. Organic horticulture relies heavily on the natural breakdown of organic matter, using techniques like green manure, the application of rotted animal manures and compost, to replace nutrients taken from the soil by previous crops.
It seems likely that the majority of organic gardeners produce their own compost. This is a basic soil amendment used in the organic approach to horticulture. Certain other amendments — such as rock powders providing phosphorus, potassium, calcium, and other minerals — have been on the market since the 1960s and earlier, though less available in some localities than others.
In addition to compost, mulches, green-manurecrops, and rock powders, organic gardeners often use prepared, naturally derived amendments – such as fish-waste emulsion (a byproduct of the fish-processing industry) or seaweed emulsion – these being concentrates, containing nitrogen and minerals, that can be mixed with water and sprayed or sprinkled on plants and soil as a booster.
These items (plus insecticidal soap, bagged rotted manure, fish emulsion, etc.) have been increasingly available through retail outlets since the 1970s. As a matter of fact, many products of this sort were (in North America, at least) developed for use at the horticultural, or garden, scale before they were developed for distribution for field-scale agricultural use. Parallel with this fact is that organic-horticulture literature, and recognition of the organic approach and methods in the standard horticulture and gardening literature, has also increased immensely during this period.
Differing approaches to pest control are equally notable. In chemical horticulture, a specific insecticide may be applied to quickly kill off a particular insect pest. Chemical controls can dramatically reduce pest populations for the short term, yet by unavoidably killing (or starving) natural predator insects and animals, cause an ultimate increase in the pest population. Repeated use of insecticides and herbicides and other pesticides also encourages rapid natural selection of resistant insects, plants and other organisms, necessitating increased use, or requiring new, more powerful controls.
In contrast, organic horticulture tends to tolerate some pest populations while looking to the long haul. Organic pest control involves the cumulative effect of many techniques, including:
- allowing for an acceptable level of pest damage
- encouraging predatory beneficial insects to flourish and eat pests
- encouraging beneficial microorganisms
- careful plant selection, choosing disease-resistant varieties
- planting companion crops that discourage or divert pests
- using row covers to protect crop plants during pest migration periods
- rotating crops to different locations from year to year to interrupt pest reproduction cycles
- Using insect traps to monitor and control insect populations
Each of these techniques also provides other benefits — soil protection and improvement, fertilization, pollination, water conservation, season extension, etc. — and these benefits are both complementary and cumulative in overall effect on site health. Effective organic pest control requires a thorough understanding of pest life cycles and interactions.
Organic pest control is not synonymous, but shares some concepts with integrated pest management.