Companion planting is the idea that certain plants can deter pests that damage other plants. Although the concept of companion planting encompasses both flowers and other vegetables, some flowers help ward off various types of pests that cause damage to your vegetable plants. By interspersing certain flowers in your vegetable garden, you will reduce problems caused by some insects and increase the health and yield of your garden.
Nasturtiums are often listed as good companion flowers for, among others, celery, radish, squash, cucumbers, zucchini and tomatoes. Nasturtiums are natural insect deterrents, and they are particularly good at discouraging white flies, Colorado potato beetles and green peach aphids. Nasturtiums grow to about 1 foot in height. In addition to being a good companion plant, nasturtium leaves are edible and can be used in salads.
Sunflowers are companions for squash and sweet corn. They are also good with cucumbers. Sunflowers were a part of the Native American Wampanoag planting scheme. The Wampanoag planting technique included planting corn, beans, squash and sunflowers in close proximity to both use each plant's strengths as an insect deterrent and each plants tendency to use different soil nutrients.
Sunflowers can also act as a support for climbing plants like cucumbers. When planting sunflower as companion plants, plant them along the north edge of your garden to keep them from shading other crops.
Marigolds have a unique odor, discernible by people, and it can deter a number of insects. Marigolds are said to ward off wild rabbits, Mexican bean beetles, nematodes and white flies. Marigolds are good companion flowers for eggplant, potatoes, pumpkins, squash, tomatoes and beans. This flower can range from 6 inches to 4 feet. Select a variety of marigold that will not either shade your vegetable crops or end up being shaded by your crops.
The old song "I'm a Lonely Little Petunia (in an Onion Patch)" suggest the use of petunias as a companion plant. Aside from onions, petunias are good companion plants for opal basil, asparagus and bell peppers. Petunias repel leafhoppers, asparagus beetles, aphids, tomato worms and Mexican beetles. The leaves of the petunia, in addition to being good in the garden, can be boiled to make a natural insect-repelling spray.