Compatible vegetables are those that can help each other when planted close together. Gardeners across generations have observed that these benefits include keeping harmful pests away, improving the health of vegetable plants and their fruit production---even enhancing the flavor of the vegetables. This garden design is also called "companion planting." Successful pairing of vegetables involves each plant providing something the other plant needs. The benefits from planting compatible vegetables occur throughout the gardening season.
Help young plants grow. Place peas and beans next to corn plants. Use the corn plants to give the bean vines something to attach to and climb, instead of using trellises or stakes. Beans will repay the favor by taking nitrogen from the air and putting it into the soil when their vines finish producing and decompose. Corn requires nitrogen-rich soil to thrive.
Protect plants from sun and heat. Shade lettuce plants from the intense afternoon sun by planting okra next to them. Use okra in this same role as a shade screen for onions. Use corn stalks to help shade squash plants and pumpkins, which in turn grow dense enough to shade the corn plants' roots. Observe how planting squash and pumpkins also prevents the growth of weeds that could rob the corn of soil nutrients and water. Plant vertical growing peas and beans next to lower growing spinach, which enjoys periods of shade.
Limit the population of garden pests. Employ plants that attract beneficial insects. Pair plants that are harmed by such pests as aphids and caterpillars with plants that attract insects to prey upon these pests. Bring in helpful insects such as wasps, spiders and ladybugs. Plant coriander, dill, parsley, carrots, hyssop and lavender to attract the desirable insects.
Drive garden pests away. Plant marigolds around the garden perimeter. They release chemical compounds through their root system that drive away pests in the soil. Include garlic in your garden plan for the same benefit to your soil. Radishes' pest control efforts include repelling cucumber beetles and squash borers. They protect spinach plants by inducing leafminers to munch on their own leaves instead. Take advantage of the herb rosemary's strong fragrance to repel pests such as cabbage moths, bean beetles and carrot flies.
Encourage a more bountiful harvest. Select plants to accelerate growth and improve fruit production. Plant leeks to boost the growth rate of both carrots and onions. Plant garlic near your rows of beets to accelerate growth, and put celery next to cabbage plants to get them growing faster. Don't put tomatoes next to carrots; tomatoes may slow down their growth.