Gathered here for easy future reference:
Plant anise and coriander seeds together. They will both germinate more quickly. Keep soil moist and separate when seedlings have grown a little.
If planted with chives there is less chance of apple scab disease.
Becomes more vigorous if planted with parsley.
Basil repels white fly and makes a good companion to tomatoes, in the garden & the kitchen. Use 3 basil plants to each tomato plant. Basil also repels flies and mosquitoes, so useful in kitchen, outdoor barbecues. Don't plant near rue. Deters tomato hornworm, aphids, flies and mosquitoes. Slows growth of milkweed bugs and acts as a fungicide.
Less likely to suffer from beetles if petunias also planted alongside. Grow more strongly if planted with summer savoury.
Bad Companions: Basil, Beets, Cabbage, Fennel, Kohlrabi, Onion, Radish, Sunflower
Plant with sunflowers, they like partial shade and the sunflowers attract birds and bees. All bean types are beneficial if planted with cucumbers, potatoes, corn, celery, savoury because these plants are heavy feeders. Beans create their own nitrogen and are light feeders.
Bad Companions: Basil, Fennel, Kohlrabi, Onion
Plant with tomatoes, it improves growth and flavour.
Grow better if planted with onions, kohl rabi, basil, beans, lettuce, cabbage and tomatoes. Planting with onions helps deter some insects and deters weeds.
Bad Companions: Mustard, Pole Bean
Attracts beneficial honey bees.
Plant with strawberries to increase crop. Also good with tomatoes and squash. Attracts bees to the garden. Deters tomato worms, attracts bees, helps growth and flavour.
Planted with dill or mint grows better.
Cabbage butterfly is repelled by planting rosemary or sage with cabbages. Any member of the cabbage family should also be planted with potatoes, tomatoes, celery, dill, chamomile, sage, thyme, mint, rosemary, lavender, beetroot or onions. All the above are aromatic plants, and therefore deter cabbage worms. Thyme and tomatoes also help control flea beetles.
Bad Companions: Pole Bean, Strawberry, Tomato
Calendula (Pot Marigold)
If planted with tomatoes, this repels asparagus beetles, tomato worms and other pests.
Long roots help break down and condition heavy soils, can plant near shallow rooted plants. Dislikes fennel. Attracts parasitic beneficial wasps. Caraway dislikes being planted near fennel. Sown with peas, caraway seeds germinate more easily.
Carrot fly is repelled if carrots are planted with sage or onions. Also plant with peas, lettuce, chives, leeks, rosemary or tomatoes.
Bad Companions: Celery, Dill, Parsnip
Planted on the vegetable garden border, catnip will deter cats from venturing further. Protects against flea beetles, and attracts bees.
Planted with bush beans, they help each other to grow better. Also good companion with leeks, tomatoes, cabbage and cauliflower.
Bad Companions: Carrot, Parsley, Parsnip
Compatible with onions and cabbages but don't plant too much. Chamomile tea, made by soaking blossoms in cold water for 1 to 2 days, is excellent spray for damping off. Improves both growth and flavour of onions and cabbages.
Chervil improves flavour of carrots if grown with them. Radishes planted near chervil has hotter taste, and improved growth.
Carrots grow larger planted near chives. Helps prevent apple scab if grown underneath apple trees. Also helps control aphids and black spot on roses. Cooled chive tea made from chopped chives in boiling water helps combat downy and powdery mildew.
Comfrey keeps surrounding soil rich and moist. Rotted leaves and roots mixed with water makes good fertiliser. Improves size and flavour of strawberries if planted nearby.
Sown with anise seeds aids germination in both. Coriander repels aphids. Don't grow near fennel as it hinders its seed formation.
Sowing with beans or peas provides an increased nitrogen supply to the corn (if corn and peas/beans are planted in alternate rows). If sunflowers are planted with corn, the incidence of armyworm decreases. Also plant with potatoes, cucumbers, pumpkin, squash. Vining things like this shade the ground, keeping weeds down, and use the corn stalks to trail up on.
Bad Companions: Tomato
Plant with beans, corn, peas, radishes, and sunflowers.
Bad Companions: Potato
Plant along garden border to produce pollen for lady beetles, lacewings, and other predators and parasites. Repels Colorado Potato Beetles.
Cabbage grows well planted near dill. So does lettuce, corn & cucumber. If dill is allowed to flower it suppresses the carrot crop, if not allowed to flower it is fine. Don't plant near fennel as they may cross fertilise.
If planted with aramanthus, there is less likelihood of insects on the eggplant. Also, beans planted with eggplants repel beetles which would otherwise attack the eggplant.
Bad Companions: Fennel
Plant near your compost heap as it assists in breakdown. Humus from base of elderberries make excellent topsoil.
Don't grow fennel in the vegetable garden. It is hated by tomatoes, kohlrabi, caraway and wormwood. If planted near dill may cross fertilise. Repels fleas, so grow it around dog kennel.
Planted near roses keeps aphids away. If grown around fruit trees effective against borers. Protects peach tree from leaf curl and apple trees from apple scab. Grown near tomatoes deters red spider mites. However peas, beans, cabbages and strawberries hate it. Garlic spray may be made by crushing 4 cloves and steeping in a litre of water for several days as an insecticide for vegetables and flowers.
Plant near roses, grapes and corn. Repels cabbage worm. Oil of geranium prevents red spider mite.
Planting clover increases the soil fertility for grapes. Hyssop likewise increases the vine crop.
Helps deter potato bug if planted near potatoes. Can take over so keep restricted.
Good for cabbages and grapes. Helps deter white butterflies. Good insect repellent if planted in vegetable or flower garden. Keep away from radishes.
Attracts butterflies. Lavender bags repel mice, ticks and moths.
Leeks grow better if planted with carrots, celery or onions.
Attracts bees. Improves growth and flavour of tomatoes.
Plant with carrots, radishes, strawberries or peas.
All round garden helper. Improves health and flavour of most plants near it.
Plant everywhere! Deter many insects and slugs.
Beneficial on most vegetables planted near it.
Plant with corn, nasturtiums, and radishes.
Bad Companions: Potato
Repels cabbage butterfly, grow near cabbage family or tomatoes. Repels fleas, ants and mice. Keep mint and parsley away from each other.
Useful insect repellent. Plant around broccoli, cauliflower, cabbage family, radishes, tomatoes, cucumbers and fruit trees. Deters white flies, squash bugs, and are a trap crop for aphids. Limits wooly aphid damage to apple trees if planted in a circle around them.
Planting chamomile with onions improves the flavour of the onions.
Bad Companions: Asparagus, Beans, Peas, Sage
Plant near broccoli, cabbage and cauliflower to repel cabbage butterfly and near cucumbers to repel cucumber beetle. Also benefits grapes.
Grow near chives, but away from mint. Aids growth of roses, tomatoes, asparagus and carrots.
Growing garlic around peach trees reduces the chance of peach leaf curl disease.
Grow them almost everywhere, peas add nitrogen to soil. Growing interplanted with corn enhances growth of the corn.
Bad Companions: Onion, Late Potato
If grown with squash or corn will increase the yield.
Plant horseradishes with potatoes to make them more disease resistant.
Bad Companions: Cucumber, Kohlrabi, Parsnip, Pumpkin, Rutabaga, Squash family, Sunflower, Turnip, Fennel
Plant with datura to increase the vigour and health of the pumpkins. Also plant with corn.
Plant with climbing beans, and both grow better. Plant with lettuces, and the radishes become more succulent in summer time. Also plant with peas, nasturtiums and cucumbers. Deters cucumber beetle and other insects.
Bad Companions: Hyssop
Planting chives or garlic with roses protects them from black spot and some pests, including aphids. Parsley protects roses from beetles.
Grows well with sage, improves growth of carrots, cabbage and beans. Don't grow near potatoes.
Hates basil. Plant near roses, strawberries and fig trees. Effective fly repellent and it repels dogs and cats which hate it.
Plant near rosemary. Good grown with cabbage and carrots, peas and beans. Keep away from cucumbers. Sage tea can be sprayed on mature plants not seedlings.
Good with thyme and mint.
Grow near onions and beans. Deters bean beetles.
Useful insect repellent.
Plant with strawberries, and base of trellised peas. Spinach benefits from shading of peas and wind protection.
Plant with corn or nasturtiums.
Planted with borage improves the soil nutrition for the strawberries. Also plant with bush beans, spinach and lettuce. Do NOT plant with tomatoes.
Bad Companions: Cabbage, Potato
Repels ants, flies and moths. Rub leaves onto fur of dogs and cats to repel fleas. Plant near fruit trees and roses. It concentrates potassium in the soil so good for compost heap.
All purpose garden helper.
Attracts bees and deters cabbage worm so plant near members of cabbage family. Beneficial effect on plants near it.
Tomatoes grow and produce better when planted with marigolds; the same rule applies to basil planted with tomatoes.
Bad Companions: Pole beans, Corn Dill, Fennel, Potato
Excellent addition to compost heap as stimulates phosphorous activity in soil. Earthworms love it.
Grow by itself edge of garden as inhibits growth of other plants. Spray discourages slugs and snails.
Increases essential oil content enhancing aromatic quality and making more resistant to insect attack.
And, VERY IMPORTANT: Interplant herbs and flowers.
By planting flowers and herbs among your vegetables, you can attract beneficial insects and birds, which are natural predators to those pests that eat your brassica leaves. Flowers and herbs can also confuse pests and deter them from finding your prize crop.
But wait, it gets better. Here's a list of herbs and the pests they repel
Flea Beetle, Ants
attracts aphids away from other plants
Japanese Beetle, Aphids
Mexican Bean Beetles, Nematodes, others
Cabbage Moth, aphids, flea beetles
Aphids, Squash Bugs, Striped Pumpkin Beetle
Flies, Mosquitoes, Fleas, others
Tomato Worm, Asparagus Beetles, others
Dried flower, repels insects
Cabbage Moth, Bean Beetle, Carrot Fly
Cabbage Moth, Carrot Fly, Flea Beetle, Slugs
Flying Insects, Japanese Beetles, Striped Cucumber Beetles, Squash Bugs, Ants, Flies
Plant as a border to repel animals