Organic gardening follows the key components of organic agriculture for conserving and improving the intrinsic health of the soil, controlling pest populations through biodiversity rather than synthetic means, promoting natural cycles of plant growth and sustaining wildlife flora and fauna. As with the rest of the organic movement organic horticulture looks to work in harmony with nature rather than against it. It is becoming increasingly popular as a preferred method of cultivating both crops and flowers as awareness grows of the potential damage to environment and health caused by synthetic chemical intervention.
Organic horticulture is the science and art of growing fruits, vegetables, flowers, or ornamental plants by following the essential principles of organic agriculture in soil building and conservation, pest management, and heirloom variety preservation. Horticulture is also sometimes defined simply as “agriculture minus the plough.” Instead of the plough, horticulture makes use of human labour and gardener’s hand tools, although some small machine tools like rotary tillers are commonly employed now. — Wikipedia
Peter Bennett, one of australia’s most respected organic experts gives a brief overview of why organic gardening is so very valuable to us and our planet:
Soil Health and Preservation
Good nutrient-rich soil results in healthy plant growth. One of the most effective ways of protecting the existing soil structure is simply covering it: green compost, leaf mould or green mulch can be spread across the surface of the soil. These substances are essentially soil improvers which will integrate with the soil by weather and worms. Alternatively they can be dug into the soil if the area is crop free. Green manure and other organic soil improvers such as plant waste or well rotted organic animal manure will also assist in improving soil structure, and will enable dry soils to retain moisture and nutrients, or increase drainage for heavy soils. It is worth noting that manures and plant waste need to be well rotted (via composting) to reduce disease causing bacteria and weed seeds. Any ‘paid for’ soil improvers ought to be organic in origin as crop or plant growth may be damaged by herbicides contained within. Liquid feeds provide nutrients for plants but are not particularly effective in improving soil structure.
Crop rotation is key to maintaining soil fertility and plant health. Crops are grouped together and rotated each year. The average rotation is 3-4 years although the longer the rotation the better. Benefits of rotation include:
- Ensuring a more balanced uptake of nutrients from the soil, given that different plants require differing amounts of nutrients. This helps maintain soil health;
- Improved control of pests and bacteria. If annual vegetable crops are grown in the same place year after year, there is a tendency for soil borne pests and diseases to become a problem, and for plant health and vigour to decline. (Garden Organic for Schools)
- Controlling weeds. Some crops will have light foliage (few leaves sparsely ocurring) and some will have denser foliage. Dense foliage helps minimise weed growth because sunlight is restricted. By alternating crops with light and dense foliage each year results in controlling weed growth.
Compost is an important element of organic gardening and has two significant positives: as an environment friendly way of recycling of garden and kitchen/household waste, and as a rich soil improver. Most gardeners using organic techniques will make their own nutrient rich compost. The following materials are all suitable for composting:
- ‘Green’ plant waste such as prunings, leaves, flower heads and grass cuttings, old bedding plants, fruit and vegetable peelings, tea bags, coffee grounds and crushed eggshells;
- ‘Brown’ kitchen/ household waste including crushed or shredded cardboard and cardboard tubes, newspaper and waste paper(ideally large amounts newspapers should be recycled for environmental reasons), soiled wood shavings, sawdust and bedding from small vegetarian pets such as rabbits, hamsters and guinea pigs and wood ash (in moderation).
Materials that should never be added to a composting site include bread, dairy, meat or fish waste (they are likely to attract vermin), coal and coke ash, long rooted weeds, dog or cat faeces, sanitary ware such as nappies, towels etc.
A compost bin needs to have a balanced mixture of green (garden waste) materials and brown (appropriate household waste). Green materials such as grass clippings and young weeds rot extremely quickly (they are thus known as activators), and will result in a smelly sludge if not balanced with slower rotting brown materials (see above).
Organic horticulture relies on a combination of control techniques which work cumulatively and in synergy with each other, benefiting the immediate plants, as well as the surrounding environment. In this way, not only is wildlife protected, but also any children or animals that interact with the plants. Straightforward approaches and tactics that are commonly applied by the organic gardener include:
- Expect and allow for an acceptable level of pest damage. Prevent significant problems through regular plant inspections to remove diseased parts of plants or initiate immediate pest control. Manage weeds as they appear by removing before they go to seed. Long rooted tough weeds should be disposed of in the dustbin rather than composted as they are easily able to propagate in a compost heap;
- Encourage beneficial insects and animals to flourish and eat pests. For example frogs and toads will happily consume slugs;
- Plant ‘companion’ crops that divert or discourage pests: For example strongly scented plants can divert specific pests away from vegetable crops;
- Use covers to protect crop plants during periods of high pest prevalence, also netting if necessary to protect from wildlife predisposed to eat fruit/vegetable crops;
- Annually rotate locations of particular crops to disturb any reproductive cycles of pests;
- Using insect traps to monitor and control insect populations.
Other benefits including fertilization, pollination, water conservation and soil improvement are inherently provided by these tactics, which will improve the general health of the site. Repeated use of insecticides and herbicides also encourages rapid natural selection of resistant insects, plants and other organisms, necessitating increased use, or requiring new, more powerful controls (Wikipedia: organic gardening).
In contrast the use os synthetic pesticides or insecticides to kill specific pests has several disadvantages. A major problem arising from such usage is that a specific insect pest population may be annihilated in the short term, but so may the beneficial insect populations that prey on that particular pest (such as bees that help pollinate flowers and fruit crops or ladybirds that consume aphids)- and the natural balance of the food chain is damaged. Once this happens the original pest population may not only return but increase in numbers significantly, as there are no longer any natural control insects. Biological controls can be purchased from mail-order suppliers. There are many available, including tiny parasitic wasps that can be used to control whitefly in greenhouses and a microscopic worm that kills vine weevil grubs. (BBC: organic gardening) Additionally chemicals reduce natural biodiversity in the garden because they kill animals, often wildlife, that accidentally consume toxic substances intended for pests. For example, birds, toads and hedgehogs may die if they eat slugs or snails poisoned with by slug pellets. Equally children and household pets are at risk.