The table below lists some commonly held beliefs about the uses of companion plants.   Plant Name Companion to: What It Is Believed To Do (Good & Bad) Allium–flowering onions, chives, garlic, leek, onion and shallot Roses, carrots, tomato, fruit trees, other vegetables Repels aphids, weevils, carrot flies, moles, fruit tree borers; controls rust flies and some nematodes; protects tomatoes against red spiders. Protects roses from black spot, mildew and aphids. BUT is believed to inhibit growth of peas & beans. Basil Tomato, asparagus Repels aphids, flies, mosquitos and mites; helps control insect pests such as tomato hornworms, asparagus beetles, and disease. Bush beans (Butter, green, snap, string,wax) Beets, carrots,cucumber, corn, eggplant, potato,strawberry Encourages growth of companion plant. Adds nitrogen to the soil. Green beans protect eggplant from the Colorado potato beetle. Borage Tomato, strawberry, fruit orchards Repels tomato worms. Adds potassium, calcium and other minerals to soil. Attracts honeybees. Broad beans Corn Add nitrogen to soil–which is needed by corn. Bean vines grow up corn stalks, thus anchoring corn more firmly and the vines discourage racoons. Chamomile Cabbage, onions Improves growth and flavor–but plant only one plant every 150 feet or so. Castor Bean Vegetables Repels moles and plant lice. CAUTION: All parts of the castor bean plant are poisonous, especially the seeds! Catnip Eggplant Fresh catnip steeped in water and sprinkled on plants will drive away flea beetles. Celery Cabbage, leeks, tomato, cauliflower Improves growth of companion plants. Repels white cabbage butterflies. Chervil Radish Improves growth and flavor. Chive Carrots Improves growth and flavor. Coriander Vegetables Repels aphids. Attracts bees. Cucumber Corn, beans, peas, radish, sunflowers Improves growth. Vines growing with corn help anchor corn and discourage racoons. Datura Various plants Deters Japanese beetles. CAUTION: All parts of the Datura plant are poisonous! Dill Cabbage Improves growth. Blossoms attract honeybees. Fennel Most plants dislike fennel–so plant it away from the vegetable garden. Its foliage and flowers may attract beneficials. Geranium Cabbage, cron, grapes, roses Repels cabbage worms, Japanese beetles. Horseradish Potato Encourages growth. May repel Colorado potato beetles and blister beetles. Hyssop Cabbage, grapes Improves growth, deters cabbage moth. Leek Carrots, celery, onions Improves growth, repels carrot flies. Marigold Tomato, potato, strawberry, beans, roses Encourages growth, deters Mexican bean beetles and other pests.. Discourages harmful nematodes, if they are grown for several seasons in the ground in areas that have nematode infestations. Mint Tomato, cabbage Improves flavor and growth Mustard Cabbage, cauliflower, radish, Brussels sprouts, turnips, collards, kohlrabi Plant mustard as a trap crop. It attracts numerous insect pests. Remove and destroy it before your main crops can be harmed. Nasturtiums Cucumber, Squash, other vegetables, fruit trees. Repels aphids,cucumber beetles,whiteflies and squash bugs. Acts as trap crop for aphids. Repels borers near fruit trees. Onion Cabbage, cauliflower, broccoli,beets, tomato, lettuce, strawberry, chamomile, summer savory Repels aphids, weevils, carrot flies, moles, fruit tree borers; controls rust flies and some nematodes; protects tomatoes against red spiders. BUT is believed to inhibit growth of peas & beans. Oregano Broccoli Repels cabbage butterfly. Parsley Asparagus carrots, tomato, roses. Deters asparagus beetles.Improves growth. Deters carrot flies and rose beetles. Peanuts Corn, squash Encourages growth of corn and squash. Peas Corn Adds nitrogen to soil for use by hungry corn plants. Grows well with carrots, turnip, radish, cumcumber, beans and potatoes. Peanut Various plants Excellent soil builder. Can make a good ground cover in a nut tree orchard. Pennyroyal Broccoli, Brussels sprouts, cabbage, other plants. Discourages ants, plant lice, cabbage maggots. Pyrethrum Various plants Repels aphids, leafhoppers, spider mites, harlequin bugs, ticks, pickleworms and imported cabbage worms. Radish Cucumber Deters cucumber beetles. Rosemary Carrots, cabbage, beans Repels carrot flies, bean beetles, cabbage moths. Rue Roses, raspberries Repels Japanese beetles. Sage Carrots, various Repels carrot flies, cabbage moths, ticks. Snap beans Corn Enhances growth of corn. Soybeans Corn Enhances growth of corn and other heavy feeders by adding nitrogen to the soil. Repels chinch bugs and Japanese beetels. Spearmint Various plants Deters ants, aphids. Sweet pepper Basil, okra Improves growth. Summer savory Green beans Improves growth, deters bean beetles. Tansy Cucumber, squash, roses, grapes, raspberry, blackberry. Deters flying insects, striped cucumber beetles, ants, flies, squash bugs and Japanese beetles. BUT, attracts imported cabbageworms. Toads (Okay, toads aren’t plants–but they sure make the greatest companions to many plants.) Various plants One toad may eat as many as 10-thousand insects in a three-month period! Insects on toad’s menu include cutworms, crickets, grubs, rose chafers, rose beetles, caterpillars, ants, squash bugs, sow bugs, potato beetles, moths, mosquitos, flies, slugs and even moles. Tomato Roses Protects roses from black spot. Thyme Cabbage Controls flea beetles, cabbage maggots, imported cabbageworms and white cabbage butterflies. Walnut, Black Black walnut trees inhibit the growth of apples, potato, tomato, blackberry. Wormwood Various plants Deters black flea beetles, malaria mosquitos, cabbage worm butterflies.

courtesy of http://www.gardentoad.com/companionplants.html

photo courtesy of http://theexchange.thegrowers-exchange.com/companion-plants-are-friends-til-the-end/