Companion planting is an organic method of growing two or more different plants together which will have mutual benefits to each other.
Companion planting is usually carried out to protect vegetable crops from pests but it can be used to attract pollinating insects to the vegetable patch, to provide higher crop yields and to increase the diversity in the soil. The other big gain is that by controlling pests naturally, you use less chemicals in your garden.
Some examples of companion planting which you might like to try in your own garden are:
Planting French marigolds next to vegetables. Marigolds are said to release a smell which confuses pests and can help to repel aphids.
Planting nasturtium flowers beside cabbages or other brassicas is said to divert aphids and other hungry insects: the cabbage white butterfly attracted by the mustard oil which the nasturtiums secrete, attack the nasturtiums instead of the attacking the brassicas, making nasturtiums a sacrificial plant.
Planting herbs near brassicas has a beneficial effect: rosemary and sage repel cabbage fly and dill attracts wasps which help with pest control.
Onions, alliums, garlic or leeks are strong smelling and planted beside carrots are said to deter the tiny carrot root fly as their strong scent is confusing to the flying insects. The ultimate in companion plants are leeks beside carrots : leeks repel carrot fly and carrots repel onion fly and leek moth so its a win-win.
Tomato plants can be attacked by greenfly but planting chives, onions or parsley beside them will lure the greenfly away from the growing tomatoes.
Planting basil beside tomatoes will attract whitefly to the basil, preventing your tomatoes or cucumbers from being attacked.
Planting basil next to tomatoes, lettuce, peppers and aubergines is also said to improve their flavour.
Rosemary planted near brassicas can repel cabbage fly.
Companion planting has uses all round the garden and you could also try planting:
Chives, thyme and lavender beside roses as their strong scents will both deter aphids and attract beneficial pollinating insects like bees, hoverflies and butterflies.
The strong onion scent from chives wards off aphids from chrysanthemums and sunflowers.
Mint is effective if you have an ant infestation in your greenhouse. Tear up a bunch of mint, scatter it and replace every few days and the ants will disappear.
Get your companion planting right and the symbiotic relationship between certain plants will ensure that your crops are bigger and more bountiful!