Companion Planting

Companion Planting is an idea as old as gardening itself. It is the notion that plants have some effect on others in the garden. It was not until recently that researchers began looking into the possibility of plant interaction. Results are still inconclusive, but in a number of controlled experiments, it has been found that some plants do indeed influence the health and growth of their neighbors. There are several ways a plant can affect another: It can attract beneficial insects, repel pests, cause a chemical reaction (these plants ‘love’ to be together), enrich the soil, shade the soil and help maintain moisture, and there are also claims that some can even improve the taste of their neighbor plant. Early gardeners considered the dandelion a good companion plant in orchards and in the vegetable patch. It has now been found that dandelions exude ethylene, a gas that encourages the setting and rippening of fruit.

As in any neighborhood, there are good neighbors and bad neighbors…Gardeners have long claimed that many plants, from the tiniest to the largest, have been considered enemies in the garden. Scientists are now uncovering evidence that some plants do practice chemical warfare on their neighbors. They accomplish this by giving off chemicals known as ‘phytotoxins’, that inhibit the growth or development of these plants. For example, the black walnut tree exudes a chemical called ‘juglone’ that prevents the growth of many plants nearby. This phenomenon is called ‘allelopathy’ and much research is being devoted to it. The research thus far has confirmed that these toxins are specific and only harm certain species. Clearly, much more work is needed to scientifically confirm all the claims, but if you find that a plant is not growing well in a particular location, and soil, water, and light are correct, you may want to look at its neighbors…

The following information has been compiled from various sources for your enjoyment, but it does not offer any guarantees: these suggestions may or may not work under your particular circumstances. It may, however, present a guideline worth investigating or provide the base for interesting experiments.



Plant Name




ASPARAGUS Basil, Parsley, Tomato None noted Parsley and asparagus are mutually beneficial in promoting one another’s health and vigor; Tomatoes contain a substance called solanine, which protects against asparagus beetles, but tomatoes also attract the natural predators of the asparagus beetle.

Asparagus Rust, Fusarium, Needle Blight, Purple Spot.

Pests: Asparagus Aphid, Asparagus Beetles.

BASIL Bell Pepper, Carrots, Marigold, Parsley, Tomato Rue Rue and basil are natural enemies
BEANS, BUSH(Butter, Green, Snap, String, & Wax) Beets, Cabbage Family, Carrot, Celery(plant sparingly), Corn, Cucumber, Eggplant, Lettuce, Pea, Marigold, Potato, Radish, Rosemary, Savory, Strawberry, Tansy, Tomato Fennel, Gladiolus, Onions and Other Alliums Only scented Marigolds will work, but not the Mexican variety: they act as a herbicide on beans and cabbage; Carrots help beans, but beans don’t help carrots; Strawberries and bush beans grow much better together than separately.

Diseases: Anthracnose, Bacterial Blight, Downy Mildew, Mosaic, Rust.

Pests: Aphids, Bean Beetles(Mexican), Beetles(Japanese), Cabbage Loopers, Corn Borers(European), Corn Earworms.

BEANS, POLE Carrots, Corn, Cucumber, Eggplant, Lettuce, Pea, Radish, Savory, Tansy Beets, Cabbage, Gladiolus, Kohlrabi, Fennel, Onion and other Alliums, Sunflower Carrots help beans, but beans don’t help carrots;

Diseases: Anthracnose, Bacterial Blight, Downy Mildew, Mosaic, Rust.

Pests: Aphids, Bean Beetles (Mexican), Cabbage Loopers, Corn Earworms, European Corn Borers, Japanese Beetles.

BEETS Bush Beans, Cabbage, Carrots, Kohlrabi, Lettuce, Onions, Sage Mustard, Pole beans These plants grow at different levels in the soil, so they do not compete for nutrients and maximize planting space; Mustard inhibits growth.

Diseases: Alternaria, Cercospora, Damping Off, Ramularia.

Pests: Bean Beetles(Mexican), Leaf Miner, Leafhoppers, Mice, Rabbits, Wireworms.

BLACKBERRIES and other cane fruit Tansy Raspberries Raspberries and Blackberries should be kept apart because of virus disease; Tansy repels harmful insects.
CABBAGE FAMILY (Broccoli, Brussels Sprouts, Cabbage, Cauliflower, Collards, Kale, Kohlrabi, Rutabaga, Turnip) Beets, Bush Beans, Celery, Chamomile, Cucumber, Dill, Garlic, Geranium, Hyssop, Marigolds, Mint, Nasturtiums, Onions, Potatoes, Rosemary, Rue, Sage, Tansy, Thyme. Grapes, Mexican marigolds, Pole Beans, Rue, Strawberries, Tomato. Mint is very invasive, but it enhances growth and health and discourages aphids, ants, flea beetles, white cabbage moths and even bunnies and other rodents; Marigolds must be scented to ward off insects, but not the Mexican variety, which acts as a herbicide on cabbage and beans; Rosemary and Sage deter cabbage moths; Thyme deters the cabbageworm; Garlic wards off pests; Chamomile improves the flavor of cabbage and enriches the soil with calcium, potassium and sulfur; Cabbage and grapes are ‘natural enemies’ – chemical warfare may be involved.

Diseases: Alternaria Leafspot, Black Rot, Black Leg, Club Root, Downy Mildew, Wirestem

Pests: Aphids, Cabbage Loopers, Cutworms, Diamond Back Moth, Flea Beetles, Imported Cabbage worm.

CARROTS Chives, Flax, Leeks, Leaf Lettuce, Onions, Parsley, Peas, Radish, Rosemary, Sage, Tomato Dill, Anise Dill and anise will reduce carrot crop; Parsley and sage protect against carrot flies by masking the carrot odor that attracts the flies; Leeks improve growth and repel carrot flies.

Diseases: Aster Yellow, Leaf spot, Soft Rot.

Pests: Carrot Rust Fly Larvae, Leafhoppers, Wireworms.

CELERY Bush Beans, Cabbage Family, Leeks, Tomatoes None noted Leeks improve its growth and repel carrot flies.

Diseases: Aphids, Black Heart, Early Blight, Late Blight, Nematodes, Septoria Leaf Spot, Viruses.

Pests: Aphids, Earwigs

CORN Amaranth, Beans, Cucumber, Geranium, Marigolds (any), Melon, Peas, Pumpkin, Potatoes, Squash, Sunflower Tomatoes Sunflower increases corn yield and relieves fall army worm/corn protects sunflower from insects; Ground vine plants shade the soil, aiding in moisture retention and their prickly vines may discourage raccoons and other corn predators; Climbing vine plants help anchor the corn stalk and make it less vulnerable to wind damage; Geranium repels Japanese beetles and cabbage worms; Peas and beans replenish nitrogen in the soil; Tomatoes and corn are subject to the same pest, the tomato fruit worm/corn earworm.
CUCUMBER Beans, Chamomile, Corn, Peas, Carrot, Nasturtium, Radish, Sunflower, Cabbage Aromatic Herbs – esp. sage, Potatoes Nasturtium deters cucumber beetles, aphids, squash bugs and other pests. Flowers are edible; Chamomile improves the flavor of cucumbers and enriches the soil with calcium, potassium and sulfur.

Diseases: Bacterial wilt, Leaf Spot, Mildew.

Pests: Cucumber beetles.

CURRANTS (Black/Red) Gooseberries White Pine Currants and gooseberries are alternate hosts for the white pine blister rust, not a serious disease for the berries, but deadly to the white pine. Most susceptible is the black currant. Planting of black currants (unless disease-free hybrids), is forbidden by law in many states.
EGGPLANT Bush Beans, Pole Beans, Spinach None noted Growing among bush beans protects from attacks of the Colorado potato beetle.

Diseases: Verticillium Wilt.

Pests: Aphids, Flea Beetles, Potato Beetles

DILL Cabbage, Cucumbers, Lettuce, Onions Carrot, Tomato Dill will reduce the carrot and tomato crop if allowed to mature near them – it may be chemistry.
GARLIC Roses, Tomatoes Aromatic Herbs, Beans, Peas, Potatoes Protects tomatoes against red spider infestation; Garlic inhibits the growth of peas and beans.

Diseases: Bacterial Soft Rots, Basal Rot, Black Mold, Blue Mold Rot, Botrytis Leafspot, Botrytis Bulb Rot, Downy Mildew, Pink Root, Purple Blotch, Stemphylium Leaf Blight, Rust, Sour Skin, White Rot.

Pests: Bulb Mites, Maggots, Pea Leaf miner, Thrips, Wheat Curl Mite.

FENNEL None noted Disliked by most vegetables and herbs, inhibited by coriander and wormwood Plant by itself, away from any other plants
GRAPES Elm trees, Geranium, Hyssop, Mulberry trees, Roses Cabbage Cabbage and grapes are ‘natural enemies’- chemical warfare may be involved; Grapes growing on elm or mulberry trees have been found to be mildew and brown-rot free; Hyssop increases yield.
LETTUCE Beans(all varieties), Beets, Carrots, Cucumbers, Onions, Radishes, Strawberries None noted Lettuce grows well with its companions; Onions may repel rabbits and other pests.

Diseases: Big Vein, Damping-Off, Downy Mildew, Mosaic Virus, Nematodes, Sclerotinia Drop, Soft Rot, Tip Burn

Pests: Armyworm, Beet Armyworm, Bulb Mites, Corn Earworm, Cutworms, Darkling Beetles, Field Cricket, Foxglove Aphid, Garden Symphylans, Green Peach, Leaf miners, Lettuce Aphid, Lettuce Root Aphid, Loopers, Potato Aphids, Saltmarsh Caterpillars, Silverleaf Whitefly, Slugs Springtails, Tobacco Budworm.

LEEK Beets, Carrots, Celeriac, Celery, Onions Beans, Peas Carrots benefit leeks and they in turn repel the carrot fly.

Diseases: Smut, Downy Mildew, Neck Rot, Pink Rot.

Pests: Onion maggots, Thrips.

MELONS Corn, Morning Glory, Nasturtium, Radish, Sunflower Potato Morning Glory thought to assist in melon seed germination.

Diseases: Alternaria Leafspot, Anthracnose, Downy Mildew, Fruit/Stem Rot (Southern Blight), Fusarium Wilt, Gummy Stem Blight, Powdery Mildew, Soft Rot.

Pests: Beet Armyworm, Cabbage Looper, Crickets, Cucumber Beetles, Cutworms, Darkling Beetles, Driedfruit Beetles, European Earwig, False Chinch Bug, Flea Beetles, Grasshoppers, Green Peach Aphid, Green Stink Bug, Leafhoppers, Leaf miners, Melon Aphid, Seed corn Maggot, Spider Mites, Squash Bug, Thrips, Vinegar Flies, Whiteflies, Wireworms, Yellow striped Armyworm.

ONION Beets, Cabbage, Carrots, Celery, Chamomile, Cucumbers, Leeks, Lettuce, Pepper, Rosemary, Squash, Strawberries, Tomato Beans, Peas, Sage Leeks improve onion growth and repel carrot flies; Chamomile improves the flavor of onions and enriches the soil with calcium, potassium and sulfur; Beets improve production of onions.

Diseases: Bacterial Soft Rot, Downy Mildew, Onion Blast, Onion Neck Rot, Pink Root, Smut.

Pests: Maggots, Thrips.

PEAS Carrots, Cucumbers, Corn, Turnips, Radishes, Beans, Potatoes, Aromatic Herbs Garlic, Onions, Leeks, Shallots Carrots produce a compound that greatly enhances pod production and quality
PEPPER Asparagus, Basil, Beets, Eggplant, Lettuce, Parsley, Rhubarb, Spinach, Tomato Fennel Growing requirements similar to basil; Peppers are brittle plants, so they benefit from being next to the taller plants for wind-protection.

Diseases: Anthracnose, Bacterial Spot, Blossom End Rot, Early Blight, Verticillium Wilt.

Pests: Aphids, Colorado Potato Beetles, Flea Beetles, Hornworms, Tarnished Plant Bugs.

POTATO Bush Beans, Cabbage Family, Corn, Eggplant, Flax, Pea Cucumber, Melons, Pumpkin, Raspberry, Squash, Sunflower, Tomato Bush beans protect against the Colorado potato beetle; the potato protects the bean against the Mexican bean beetle; Flax contains tannin that repels the Colorado Potato Bug; Tomatoes make potatoes more susceptible to potato blight; Raspberries make potatoes susceptible to blight; Flax enhances growth and repels the Colorado potato beetle.


Black Leg, Early Blight, Late Blight, Potato Blight, Speckle Leaf, Ring Rot.

Pests: Colorado Potato Beetles, Pocket Gophers.

PUMPKIN Corn, Radish Potato Potato and Pumpkins inhibit one another’s growth.

Diseases: Anthracnose, Bacterial Wilt, Downy Mildew.

Pests: Cucumber Beetles, Squash Vine Borers.

RADISH Beans, Beets, Carrots, Corn, Cucumbers, Lettuce, Nasturtium, Squash, Spinach, Parsnips Cabbage, Cauliflower, Brussels Sprouts, Broccoli, Hyssop, Kohlrabi, Turnips Nearby lettuce may make radishes more tender; Beans increase nitrogen in the soil.

Diseases: None

Pests: Aphids, Cabbage Maggots, Flea Beetles.

RASPBERRY(Red) Garlic, Tansy Blackberries, Black Raspberry, Potato Garlic and tansy repel insects; Blackberries and black and purple raspberries should be planted at least 600 feet away from the red varieties because of virus disease susceptibility.
ROSE Chives, Garlic, Geranium, Hyssop, Lupine, Onion, Shallots, Tansy, Tomato Boxwood and other woody plants with prolific root systems Garlic causes roses to produce a stronger perfume; Parsley protects against rose beetles; Onions repel rose chaffers; Lupines increase soil nitrogen and invite earthworms; Tomatoes protect from black spot disease; Hyssop deters flea beetles and cabbage moths; Woody plants with large root systems will compete for soil nutrients.
ROSEMARY Beans, Cabbage, Carrot, Sage None noted Taste of cabbage and beans is improved by Rosemary; Grows well with sage.
SAGE Cabbage, Carrot, Rosemary Rue Sage improves the taste of cabbages.
SHALLOTS Beets, Cabbage, Carrot, Chamomile, Mint, Sage, Thyme Beans, Peas The herbs improve the flavor of shallots; Beets and carrots grow at different levels in the soil, so they do not compete for nutrients.
SPINACH Cauliflower, Celery, Eggplant None noted Spinach is rich in saponin, a soil-beneficial compound.


Anthracnose, Spinach Blight, Damping Off, Downy Mildew.

Pests: Aphids, Army Worms, Crown Maggots, Flea Beetles, Leafhoppers, Leaf Miners, Loopers, Slugs.

SQUASH Corn Potato Corn provides shade for the squash; Squash prickly vines keep predators away and cover the soil to help retain moisture.
STRAWBERRY Borage, Bush Beans, Lettuce, Onion, Spinach Cabbage and family members Borage increases beneficial natural minerals in the soil. It also controls insects.

Disadvantage: Borage is very invasive. Do not plant strawberries where tomatoes, potatoes, peppers or eggplant have been grown in the past four years, because these crops carry the root rot fungus Verticillium which also attacks strawberries.

SUNFLOWER Corn, Cucumber Pole Bean, Potato Corn and cucumber yield is increased by nearby sunflowers; Sunflowers are also useful in aphid control.
TANSY Blackberry, Cabbages, Grapes, Peach trees, Raspberry, Rose Collard Tansy is a good insect repellent. It increases Potassium in the soil, so it benefits most plants nearby (does not like collards). It is helpful under Peach trees, which it assists by discouraging flying insects & deterring Borers from the trees. It also protects against the Japanese Beetle, Striped Cucumber Beetle, Squash Bug, Cut Worms, Cabbage Worms, Ants, Flies, Mosquitoes & Fruit Moths.
TOMATO Asparagus, Basil, Borage, Carrots, Celery, Chives, Bell Pepper, Horehound, Mint, Monarda (Bee Balm), Nasturtium, Onion, Parsley Corn, Dill, Kohlrabi, Potato, Fennel Basil improves flavor and protects against insects; Horehound encourages fruiting; Bee Balm aids in both growth and flavor (caution: Bee Balm is a mint and is invasive!); Potatoes inhibit the growth of tomatoes.
THYME Cabbage family, Eggplant, Onion, Potato, Sage, Tomato None noted May be planted with all plants. It enhances the fragrance of other herbs, protects against insects, improved taste of companion vegetables, and is an all-around nice and useful plant.
ZUCCHINI Beets, Corn, Lettuce, Lovage, Nasturtiums, Parsley, Peppermint, Peppers, Spinach, Squash, Tomato Potato Zucchini (as other squash) don’t like Potatoes. It may be that they compete for soil nutrients and they are both susceptible to common pests; Nasturtiums, Parsley, Peppermint repel various insects; Spinach enriches the soil.


Leave a comment