Companion planting is not a new idea. Gardeners have been using companion planting techniques for thousands of years. The flowers recommended for vegetable gardens serve many purposes. Some of the flowers are edible; some flowers attract beneficial insects; other types of flowers repel garden pests and disease. Successful companion planting is about more than just planting pretty flowers in the vegetable garden. Knowledge of what plants make good companions is necessary.
Marigolds are a popular annual flower easily grown from seed. Often grown in flowerbeds, the marigold flowers recommended for vegetable gardens do more than just make a pretty border plant.
Grow French marigolds, Tagetes patula, in gardens to rid the soil of nematodes. Plants subject to infestation by root knot nematodes include beans, peas, carrots, celery, eggplant, members of the cucurbit family, onion, pepper, tomato, sweet corn, potatoes, sweet potatoes and leaf crops. The smell of the flower repels rabbits and whiteflies.
Mexican marigolds, Tagetes erecta, will overwhelm bindweed roots, eliminating them from the vegetable garden and repel the Mexican bean beetle.
The odorless marigold, Crown of Gold, deters Japanese beetles.
Marigold flowers are edible. The best tasting marigold is Lemon Gem, botanically known as Tagetes signata. Other botanical names are Tagetes pumila and Tagetes tenufolia.
Marigolds, like other flowers recommended for vegetable gardens, attract numerous beneficial insects, including butterflies and hoverflies. Non-beneficial insects they attract include spider mites and slugs. Deter slugs by sprinkling diatomaceous earth around the base of the plants.
Do not plant marigold flowers near beans or members of the cabbage family due to the herbicidal effect of the plant.
Nasturtiums, another pretty, edible plant, is among the flowers recommended for vegetable gardens because it repels squash bugs, wooly aphids, whiteflies, bean beetles, cucumber beetles and other pests of the cucurbit family. All nasturtiums will trap aphids; however, nasturtiums with yellow flowers are especially attractive to them.
Fruit trees can benefit from climbing nasturtiums planted around the tree trunks. Train the vines so they will grow up the trunks of fruit trees to repel pests, such as the codling moth that attacks apple trees. Tomatoes, cabbage and cucumbers also benefit from nasturtiums grown in a circle around them.
Flowers recommended for vegetable gardens that thrive in dry conditions include the zinnia. Hummingbirds, which eat whiteflies, bees, butterflies and numerous insect pollinators, swarm the nectar-filled flowers. Zinnias attract beneficial insects such as lacewings, ladybugs, hoverflies and parasitic wasps.
Plant pastel-colored zinnia as a trap crop for Japanese beetles. The flowers of this plant also deter the cucumber beetle and tomato hornworm.