One of the best reasons for growing your own vegetables is that you can be absolutely sure how they have been grown and what has been sprayed on them. The aim of organic gardening as well as the organic hydroponic grow systems is to work with nature. So relying on natural predators to keep down pests plays a large part. There is little point trying to grow your vegetables organically if you regularly use aphid sprays on your flowers as you will remove the natural predators’ source of food. Anything you can do to encourage a wide range of wildlife into the garden – by creating favorable habitats such as ponds, meadows and hedgerows, for example -will make it more likely that natural predators will help to control pests on your vegetables.
Feeding the soil
Organic gardeners aim to build up soil fertility over the long term, rather than supplying soluble man-made nutrients directly to plants. In addition, you might want to consider where manures have come from: for example, an organic farm rather than a conventional one.
Another environmental concern is that the nutrients are washed out of manure and garden compost while they are being stored and once they have been applied to the soil. In the past, nutrient-rich organic matter such as manure was applied during winter digging, but there is now a move to delay putting it on until after the winter rains. If applied in spring just before sowing or planting, or in summer to growing crops, the plants will benefit from the nutrients.
It is now recommended that more care is taken over the amount of manure applied: no more than about one barrow-load of manure or two barrow-loads of garden compost to ten square metres of ground each year. If you follow a crop-rotation system, apply manure to the crops that benefit most.
Organic fertilisers
If you do not have sufficient garden compost or bulky organic matter, you can use concentrated organic fertilizer, provided it is of animal or plant origin. For example:
Animal-based fertilizers – Dried blood is a source of quick-release nitrogen. Hoof-and-hornmeal is a slower-release form. Bonemeal is a natural source of phosphate. Blood, fish and bone is a balanced fertiliser, but lacks potash.
Seaweed meal and seaweed extracts are useful sources of small amounts of minor nutrients or trace elements.
Home-made liquid feeds provide nutrients for plants in containers. Comfrey feed, for example, is made by packing fresh comfrey leaves into a water butt and collecting the liquor that runs from the tap at the bottom. It is the best natural source of potash so could be used instead of a tomato feed.
Pest and disease control
There are many ways to prevent damage by pests or diseases:
- crop rotation.
- physical barriers such as fine-mesh netting and sections of plastic drink bottles
- sowings timed to miss the most vulnerable period
- hand-picking larger pests such as slugs, snails and caterpillars
- encouraging insect predators such as ladybirds, lacewings and hoverflies, ground beetles, hedgehogs and birds, which will eat aphids or other pests
- in the greenhouse, biological control is an effective alternative to chemicals.
Acceptable pesticides
Generally, organic gardeners do not use pesticides, but some based on naturally occurring substances can be used as a last resort. Bordeaux mixture can be used to prevent potato blight.
Insecticides based on soft soap, plant fatty acids, derris and pyrethrum are all acceptable. Although these products are derived from natural materials, they will also kill beneficial insects, so should be used with care – in the evening when bees are not active, for example.
Weed control
Weeds are kept under control by mulches, hoeing and hand weeding. Not digging also reduces the amount of weed seed brought to the surface.
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