Seasoned vegetable gardeners use companion plantings as strategically as expert chess players move their pawns. Based on historical observation and horticultural science, companion planting is the process of planting certain crops together for the symbiotic benefits they derive from each other. Used effectively, companion planting reduces pests and increases harvests without the use of chemicals. While the process takes planning and education, you'll reap the rewards of a healthier, more productive garden.
Plant companion crops for pest control. African marigolds release thiopene, a natural nematode repellent, according to the National Sustainable Agriculture Information Service. Plant them near any crops vulnerable to nematode infestation, including cabbage, broccoli and tomato.
Plant crops that provide symbiotic nitrogen fixation. Native Americans traditionally planted green beans along with corn. Corn is a heavy feeder, requiring plenty of nitrogen. Beans naturally fix nitrogen in the soil, making it more available to plants. Planted together, corn shades beans from summer heat, while beans provide nutrients to the corn.
Attract beneficial insects through companion planting. Beneficial insects are predatory insects such as lacewings and ladybugs that eat vegetable-munching bugs. For example, plant dill alongside cabbage. The dill attracts the tiny wasps that eat imported cabbage worms. Nasturtium is a flowering annual that attracts many beneficials. Intersperse it throughout your garden.
Save space in your garden by planting vining crops such as squash, zucchini and melon with tall crops such as corn. The vines shelter the soil, preventing weed growth and moisture loss. They're also said to discourage raccoons and squirrels from eating your corn.