Companion plants, beneficial associations

Companion planting is a technique used before the advent of pesticides and other insecticides to optimize the development of vegetables and flowers by wisely choosing the varieties to grow together. As a matter of fact, some plants have the ability to repel or even kill insects harmful to other plants. Others, on the other hand, are particularly fit to attract these insects and sacrifice themselves to save others. In short, companion planting has countless virtues.

Concerning companion plants, certain combinations are particularly advised against. Some associations to be avoided are the potato and tomato, beans and onions, and lettuce and broccoli. The companion planting technique is making a strong comeback as an alternative method allowing, as much as possible, to avoid the use of pesticides and insecticides.

Overview of companion plants

Aphids are probably the most destructive insect pests in vegetable gardens and flower gardens. Rose bushes, potatoes, turnips, apples, cabbage, grapes, etc … the aphids’ victims are numerous. Fortunately, the companion plants used to eliminate them are also very diverse. To drive them away, one can, for example, plant fennel, dill, milkweed, anise, chives, rosemary, lavender or Valerian. Mustard and nasturtium, on the other hand, have the ability to irresistibly attract them, and when these plants are totally infested by insect pests, simply cut and burn them.

To ward off Colorado potato beetles which, as their name suggests, attack potatoes, just grow them near dandelion, coriander, horseradish, tansy, datura or, to kill two birds with one stone, tomato. Some plants have the ability to keep almost all insects at bay. Among these, we can include elderberry, rosemary and, for those with a large garden, eucalyptus. Mugwort, meanwhile, not only wards off nearly all insects but also slugs, snails and even rodents. Fennel grown between the rows of lettuce protects them from the attacks of slugs that cannot stand their scent. When they release their fragrance, aromatic plants prevent parasitic insects from recognizing their usual preys.

Recommended companion plant associations

As nature would have it, some plants protect each other when grown together. Carrots, for example, protects tomatoes from aphid attacks while the tomato keeps flies away from carrots. The onion has the same action on the carrot, while the latter drives flies away from onions. Let us list a few companion plants that are grown with our favourite vegetables: potatoes very much appreciate the company of lettuce, onion, cabbage and radish; the carrot grows wonderfully near onions, tomatoes, leeks and radishes; tomatoes prefer to be in the vicinity of carrots, parsley onions, etc … Note that the onion is not only a popular vegetable, but an incomparable companion plant. Legumes, such as beans, trap nitrogen in the air and then release it into the ground, which is very appreciated by leafy vegetables, especially lettuce, that are particularly fond of this substance.

Published in Organic by Alexander on 14 Sep 2011