Companion Plants to Grow With Vegetables

Ornamentals

• Marigolds are probably the best known ornamental companion plant. Some gardeners plant them in hopes that their strong odor will keep insect pests away. While the idea of using marigolds to repel pests is based in tradition, there is a scientific basis to the idea that French marigold roots produce a chemical that destroys pathogenic nematodes. Nasturtium with beans, cabbage, cucumber, celery, melons, pumpkins and squash controls pests and, with radishes, improve flavor. Because they attract aphids, they can divert aphids from your vegetable crops. Bee balm benefits tomatoes.

Herbs

• The same pest-control principle of "repel with smell" applies to strong-scented herbs. Mint, rue, sweet basil, tansy, summer savory, cilantro, rosemary, thyme, sage and oregano all repel common vegetable plant pests. Basil, bee balm, chives and mint are said to improve the growth and flavor of tomatoes. The flowers of borage provide a food source for beneficial insects that can help control vegetable pests, so borage makes a welcome -- and attractive -- addition to the vegetable garden. Growing chamomile and summery savory improves the flavor of onions.

Other Vegetables

• According to the concept of companion planting, vegetables can influence neighboring vegetable plants as well. In some cases, this makes clear sense. Beans, for example, fix nitrogen and improve soil fertility for nearby plants. In the traditional "Three Sisters" combination of squash, corn and beans, the cornstalks act as a trellis for the beans and protect the squash from pests.

  In other cases, the pairings seem to make less sense. For example, tomatoes are said to grow well with asparagus, carrot, celery, cucumber, onion and pepper. Cucumbers grow well with beans, members of the cabbage family, corn, peas, radishes and tomatoes. Carrot, eggplant, onion and tomato are said to help peppers thrive.

Pairings to Avoid

• If plants excel around some species, they under-perform in the company of others. Garlic and onion are poor companions for beans and peas. Because the same pest attacks tomatoes and corn, and the same diseases attack tomatoes and potatoes, these plants make poor companions for each other.