Companion planting refers to the garden design concept of mixing vegetables together in a way that will help them grow more rapidly and even improve the flavor of the fruit. Plants are meant work together in the garden ecosystem. For example, certain vegetables can protect other ones from pests. There are also cases where certain varieties of plants should not be close together in a garden because they are both affected by the same diseases or pests. Intercropping some kinds of herbs and vegetables can also have beneficial effects on both.
Corn, Pumpkins, Beans and Cucumbers
This group may seem like an unlikely team given the very different sizes of the mature plants. Beans need something to latch onto for support as they grow like a stake or a trellis. A tall corn stalk fits the bean plant's needs perfectly. Beans in turn contribute nitrogen to the soil after they finish producing and die, which benefits the corn plant. The pumpkin plant's thick foliage and low growing pattern helps keep weeds from rising up. The pumpkin plant can also shade the corn plant's roots and keep them from drying out. Cucumbers can substitute for beans in this mini-ecosystem, climbing up the corn plants.
Radishes and Squash
Radishes are one of the most effective plants at controlling pests that attack other vegetables in the garden, such as the destructive squash borers. They also ward off cucumber beetles. As they go to seed, their effect intensifies and they can even have an impact on controlling corn borers.
Tomatoes and Other Plants
Tomato plants that are mature and healthy can be big enough to protect chili pepper plants from sun and wind damage. They may cause carrots to grow more slowly than normal but do not affect the flavor. Tomatoes and corn are not a good pairing because they can be infested with the same species of worm. Tomatoes and potatoes are both susceptible to blight and may infect each other if planted too close together. Tomatoes and peppers make good companions, as do tomatoes and beans. Beans are appreciated by spinach for the shade they can provide.
Okra, Onions, Peppers, Eggplant and Leeks
Okra can serve as a shade screen for lettuce plants sensitive to the hot afternoon sun. It can be paired with peppers in the garden as well, providing them some welcome humidity. Eggplant and peppers can assist each other with healthy growth. Okra helps onions by serving as a shade and wind screen. Onions in turn can prevent the onset of certain diseases in strawberries. Leeks help stimulate growth in carrots as well as in its relative, the onion. Leeks can even keep pesky onion flies away.