The theory of companion planting is by placing beneficial plants together they help each other grow. Some ways companion plants help each other are:
- Taller plants can provide shade for sun-sensitive shorter plants.
- Vine plants cover the ground below taller plants for weed control, or to support vine plants.
- Companion plants discourage pest, for instance onions repel some pests,
while other companions, like marigolds, lure pest away from desirable plants. - Companion planting can attract beneficial insects to the garden, and improve flavor to some fruits and vegetables.
Below is a beginner’s guide to companion planting.
Basil
Plant near: most garden crops
Keep away from: rue
Comments: improves the flavor and growth of garden crops, especially tomatoes and lettuce. Repels mosquitoes
Beans, Bush
Plant near: beets, cabbage, carrots, catnip, cauliflower, corn, cucumbers, marigolds, potatoes, savory, strawberries.
Keep away from: fennel, garlic, leeks, onions, shallots.
Comments: potatoes and marigolds repel Mexican bean beetles. Catnip repels flea beetles.
Beans, Pole
Plant near: corn, marigolds, potatoes, radishes.
Keep away from: beets, garlic, kohlrabi, leeks, onions, shallots
Comments: same as for bush beans.
Beets
Plant near: broccoli, brussel sprouts, bush beans, cabbage, cauliflower, chard, kohlrabi, onions
Keep away from: mustard, pole beans
Borage
Plant near: squash, strawberries, tomatoes
Keep away from: Spreads by seed!!
Comments: repels tomato worms. Improves flavor and growth of companions.
Broccoli and Brussels Sprouts
Plant near: beets, buckwheat, calendula, carrots, chamomile, dill, hyssop, marigolds, mints, nasturtiums, onions, rosemary, sage, thyme, wormwood.
Keep away from: strawberries
Comments: marigolds repel cabbage moths. Nasturtiums repel aphids.
Cabbage and Cauliflower
Plant near: broccoli, brussels sprouts, celery, chard, spinach, tomatoes.
Keep away from: strawberries
Comments: tomatoes and celery repel cabbage worms.
Cantaloupe
Plant near: corn
Keep away from: )
Carrots
Plant near: cabbage, chives, early potatoes, leeks, lettuce, onions, peas, radishes, rosemary, sage, salsify, wormwood.
Keep away from: )
Comments: onions, leeks, and wormwood repel carrot flies
Chives
Plant near: apples, berries, carrots, grapes, peas, roses, tomatoes.
Keep away from: – )
Comments: Deters aphids and Japanese beetles. Improves flavor & growth of companions.
Corn
Plant near: beans, cucumbers, early potatoes, melons, peas, pumpkins, soybeans, squash.
Keep away from: -)
Comments: soybeans deter chinch bugs.
Cucumbers
Plant near: beans, cabbage, corn, early potatoes, radishes, sunflowers.
Keep away from: late potatoes
Comments: Radishes deter cucumber beetles. Cucumbers encourage blight in late potatoes.
Dill
Plant near: broccoli, brussels sprouts, cabbage, cauliflower, cucumber, lettuce, onions
Keep away from: carrots
Comments: Improves flavor and growth of cabbage family plants.
Eggplant
Plant near: green beans, peppers, potatoes, tomatoes
Keep away from: –
Comments: green beans deter Colorado potato beetles.
Garlic
Plant near: cabbage, cane fruits, fruit trees, roses, tomatoes
Keep away from: peas, beans
Comments: deters Japanese beetles and aphids. A garlic oil spray deters onion flies, aphids, and ermine moths. A garlic tea helps repel late potato blight.
Kale
Plant near: aromatic herbs, buckwheat, cabbage family, marigolds, nasturtiums
Keep away from: pole beans, strawberries
Kohlrabi
Plant near: cabbage/cauliflower companions (except tomatoes)
Keep away from: fennel, pole beans, tomatoes
Comments: kohlrabi stunts tomatoes
Lettuce
Plant near: beets, carrots, parsnips, radishes, strawberries
Keep away from: cabbage family
Comments: lettuce tenderizes summer radishes.
Marigolds
Plant near: all garden crops
Keep away from: -)
Comments: stimulates vegetable growth and deters bean beetles, aphids, potato bugs, squash bugs, nematodes, and maggots.
Marjoram
Plant near: all garden crops
Keep away from: -)
Comments: stimulates vegetable growth.
Mustard
Plant near: alfalfa cover crops, fruit trees, grapes, legumes
Keep away from: -)
Comments: stimulates growth of companion plants.
Nasturtiums
Plant near: apples, beans, cabbage family, greenhouse crops, potatoes, pumpkins, radishes, squash
Keep away from: -)
Comments: repels aphids, potato bugs, squash bugs, striped pumpkin beetles, and Mexican bean beetles and destroys white flies in greenhouses.
Onions
Plant near: beets, cabbage family, carrots, chamomile, lettuce, parsnips
Keep away from: beans, peas
Comments: deters most pests, especially maggots.
Oregano
Plant near: all garden crops
Keep away from: -)
Comments: deters many insect pests.
Parsley
Plant near: corn, roses, tomatoes
Keep away from: –
Parsnips
Plant near: onions, radishes, wormwood
Keep away from: -)
Comments: onions and wormwood help keep root maggots from parsnips.
Peas
Plant near: beans, carrots, corn, cucumbers, early potatoes, radishes, turnips
Keep away from: garlic leeks, onions, shallots
Peppers
Plant near: basil, carrots, eggplant, onions, parsley, tomatoes
Keep away from: fennel, kohlrabi
Potatoes
Plant near: basil, beans, cabbage family, corn, eggplant, flax, hemp, marigolds, peas, squash
Keep away from: apples, birch, cherries, cucumbers, pumpkins, raspberries, sunflowers, tomatoes, walnuts
Comments: Basil deters potato beetles. Marigolds (dug into crop soil) deter nematodes, hemp deters phytophthora infestans (potato blight)
Radishes
Plant near: chervil, cucumbers, lettuce, melons, peas, nasturtiums, root crops
Keep away from: hyssop
Comments: radishes deter cucumber beetles. Chervil makes radishes hot. Lettuce helps make radishes tender. Nasturtiums improve radishes’ flavor.
Rosemary
Plant near: beans, cabbage, carrots
Keep away from: -)
Comments: repels bean beetles, cabbage moths, and carrot flies.
Sage
Plant near: cabbage family, carrots, tomatoes
Keep away from: cucumbers
Comments: deters cabbage moths and carrot flies. Invigorates tomato plants.
Soybeans
Plant near: corn, potatoes
Keep away from: -)
Comments: chokes weeds and enriches soil.
Spinach
Plant near: celery, cauliflower, eggplant, strawberries
Keep away from: -)
Strawberries
Plant near: borage, bush beans, lettuce, pyrethrum, spinach
Keep away from: cabbage family
Sunflowers
Plant near: cucumbers
Keep away from: potatoes
Comments: can provide a trellis and shelter for shade-loving cucumbers.
Swiss Chard
Plant near: bush beans, kohlrabi, onions
Keep away from: pole beans
Tarragon
Plant near: all garden crops
Keep away from: –
Comments: improves vegetables’ flavor and growth.
Thyme
Plant near: all garden crops
Keep away from: –
Comments: deters cabbage moths.
Tomatoes
Plant near: asparagus, basil, cabbage family, carrots, gooseberries, mustard, parsley, onions, rosemary, sage, stinging nettles.
Keep away from: fennel, kohlrabi, potatoes, walnuts
Turnips and Rutabagas
Plant near: peas
Keep away from: knotweed, mustard
Comments: mustard and knotweed inhibit the growth of turnips and rutabagas!
By Carlotta Lucas Ashland Garden Club
By: Dianne Machesney, Master Gardener, Allegheny County: “Three-fourths of the world’s flowering plants and one-third of our food supplies depend on pollination. Pollinators need plants year-round. The succession of flowers throughout the seasons provide nectar, eggs are laid on host plants ensuring reproductive survival, plants and debris left in the garden serve as safe places for pollinators to overwinter. By planting a variety of native flowering species, and leaving them to stand in our winter gardens, we greatly add to the diversity and abundance of pollinators. ” Penn State Extension: 
By Justin Wheeler, Xercres Society: “One of the most valuable things you can do to support pollinators and other invertebrates is to provide them with the winter cover they need.” 