Companion planting means arranging the plants in a garden in such a way that they enhance the growth and quality of nearby crops, provide maximum ground cover, and, if possible, improve the soil.
Companion plants are also a way of controlling insect populations. Fragrant flowers and herbs drive away pest insects. For example, an annual with a strongly fragranced leaf and blossom that many insects find unattractive is the marigold. Not only does its strong odour confuse pests looking for their favourite plants, but their roots give off a substance which repels nematodes. Planting a couple of rows of marigolds around the edge of your garden will add both beauty and a measure of protection for your vegetables.
Antagonist plants as their name implies have negative effects when planted together, and should therefore be grown apart from each other.
Plants may be good Companions because:
They like the same soil and weather conditions
One helps the other by loosening the soil for its roots
One gives welcome shade and protection to its companion
One attracts an insect that is beneficial to the other
One deters a pest that habitually attacks the other for instance sage, rosemary, thyme
repel the cabbage butterfly; onions and leeks repel the carrot fly.
One may leave a residue in the soil that benefits its companion.
Plants with strong odours do confuse, deter, and often stop some pests.
Some plants hide other certain plants we dont want detected.
Some plants (especially herbs) are considered nursery plants for beneficial insects,
providing shelter, nectar, pollen, and even dark, cool moist spots.
Listings of companions and antagonists are given. To interpret the lists:
CABBAGE FAMILY: includes Broccoli, Brussels Sprouts, Cauliflower, Kohlrabi
MARROW FAMILY: includes Courgette, Cucumber, Pumpkin, Squash
ONION FAMILY: includes Chives, Garlic, Leek