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What is a companion plant?

We all know that the people we hang around with affect us. Imagine your mother saying, "Don't you have any nice friends? Why don't you spend some time with that girl next door? She's so well-behaved and polite. It wouldn't hurt you to be with someone who would be a good influence."

Well, plants can be the same way.

A companion plant is one that is beneficial to the growth of another, more important plant. A companion plant might distract pests away from the main plant or attract beneficial insects into the area.

One of the most well-known companion plants is the marigold, which can be planted near tomatoes, roses or cabbages. Marigolds work their magic in several ways: they reduce the number of nematodes (parasitic worms) in the soil; they attract hoverflies, which feed on aphids; and they deter Mexican bean beetles, which damage leaves and kill plants.

In the world of serious gardening, there are a great many well-known companion plants. For example, other plants that are beneficial to tomatoes are asparagus, basil, beans, borage, cabbage, onion, parsley, pea and sage. Borage is also a good companion to strawberries and potatoes.

You might be wondering, are there plants that are a bad influence on other plants? The answer is yes. They are called antagonistic plants. For example, some of the antagonistic plants than can hurt tomatoes are carrot, cauliflower, chives, fennel and potato. No doubt, these are the plants mother tomatoes warn their children about.