Organic gardening is gardening that uses substantial diversity in pest control to reduce the use of the weapon of pesticides and tries to provide as much fertility with local sorces of nutrients rather than purchased fertilizers. The term may have ironically arisen as response to the effects observed in farming in the first half of the twentith century of to the evolving science of organic chemistry. It is said by some of its supporters to be more in harmony with nature. Organic gardeners emphasise the concept that "the soil feeds the plant".

Soil fertility is enriched by the addition minerals and humus. Minerals are obtained from a varity of sources, such as calcium from fossil or recently deceased shellfish, potasium from wood ash, nitrogen from the animal urea in manures or legumes, and phosphorus from bone. Humus is a product of composted vegetable matter. Composting is a process by which vegetable matter (e.g., grass clippings, food waste, leaves) are allowed be consumed by bacteria, fungus, worms and insects until what remains is mostly the cellulose and minerals of the original vegetable matter. This is utilized as a soil amendment. The cellulose in humus acts like a sponge and holds moisture in the garden soil, available for the growing plants.

Control of animal pests can be achieved through natural methods, including crop rotation, physical removal of insects, introduction of prey species, interplanting which reduces the spread of pests and disease that agribusiness monocroping accentuates and through the use of companion planting of plants which may demonstrate pest-repellant characteristics.

For the organic grower, vegtable pests or weeds are supressed without the use of herbicides. Barriers are often used to provent weeds from reaching the light they need to grow. Generally called mulches, they can include stones, leaves, straw or wood. Paper can make an excellent barrier which, like leaves, straw and wood, will return its cellulose to the soil. These barriers have the added effect of keeping moisture in the soil below them. Some writers even refer to soil loosened by hoeing and tilling as dirt mulch. There are many forms of tilling devices and cultivators which supress weeds by mechanically disturbing the weeds' roots and preventing them from taking up water and nutrients.

The United States Department of Agriculture (USDA) has recently established standards which must be followed by any growers who wish to label their produce as "organic". Many small-scale gardeners and farmers have neither the time nor resources to comply with the USDA's extensive record-keeping requirements. These growers often market their produce under alternative labels, such as "naturally grown", "chemical free", and the like, although some contend that they use growing methods superior to those specified by the USDA organic program.

The UK has a stringent certification procedure, for organic producers and retailers, which is considered to have the highest standards in the World. Many of the materials and practices allowed in other countries are outlawed in the UK.

Systems of organic gardening include: biodynamic agriculture which predates organics by some 20 years, permaculture which emerged in the mid 1970's, and cultivation from the Latin verb colere which includes the meaning, to till. Cultivation and the culture around it predates the Latin language and wherever history is the written word, it is prehistoric.

For more detailed information on subjects relevant to organic gardening and farming see the list of organic gardening and farming topics.

• Natural organic fertilizers
• Your Organic Gardening Guide - Free Articles, Tips and Resources on Organic Gardening