Companion Planting for Pest Control

Posted by: gardenretreat  :  Category: Pest and Weed Control

(from our July 2012 newsletter)
July is here and finally we can see some growth in our gardens!! With all this rain, I hope you have had an opportunity to divide what perennials needed to be divided and transplant out all your vegetables to the garden. I always start my vegetable beds with what I call my “green crop”. The first thing to go into my vegetable beds is my lettuces which I over seed like crazy (anticipating frost and cold weather to take a few or a lot of my heads) but this year, they all took! I’m usually turning them into the soil for an extra nitrogen boost for my other vegetables but not this year. I planted them earlier than usual, first week of May, but with our new house I didn’t know what to expect, so now I have 20 heads needing harvest daily. The neighbours are sure happy!!

 This month’s to do list involves a lot of maintenance… go figure…

 If you have planted potatoes and carrots now is a good time to hill the soil to prevent green shoulders! Also, continue to stake and tie up your tall plants i.e. Peas, roses, raspberries, etc. If you have flowers ‘a galore’ in your garden, why not make a nice bouquet for inside and create a bunch of new blooms outside, instead of early seeds? Make sure you are watering your annuals at least 3 times a week during periods of intense heat, so they are not spoiled before you know it! And if you do have mature plants that you are ready to harvest seed from, make sure you are choosing the healthiest plants (don’t forget to label your storage containers too).

This month I want to talk about companion planting. It is a very important part of integrated pest management, and since we are leaning towards a greener way of growing these days, I think it would be helpful information to have. Plants have natural substances that can alternately repel or attract insects depending on our needs. In essence, companion planting helps bring a balanced ecosystem to our landscape, and allows nature to do its job. By using companion planting, gardeners have found that they can discourage harmful pests without losing the beneficial allies! Companion plants can interplant in your flower or vegetable beds wherever your specifics needs require. It is always a good idea to use plants that are somewhat native to your area so the insects you want to attract already know what they are looking for! And a helpful tip is that plants with a cup shaped flower are the most popular for beneficial insects.

The following list is just a few popular plants I have selected for this month’s newsletter. I encourage you to do further research for your specific needs as companion planting can truly add beauty and purpose to your garden as well as a healthier environment free of pesticides. This list is not intended to solve all your pest problems, just a healthy alternative to try. I suggest you experiment with different plant options and see what works! Share your ideas and trials with your neighbours as this will encourage more of the ‘good bugs’ to your community which benefits everyone!

ALFALFA: This perennial deeply roots, fixes the soil with nitrogen, accumulates iron, magnesium, phosphorous and potassium. Withstands droughts with its long taproot and can improve just about any soil! Alfalfa has the ability to break up hard clay soil and can even send its’ roots through rocks! (perfect forCalgary’s soil)  Alfalfa is practically pest and disease free. It needs only natural rainfall to survive. Try it as a green manure where you are having trouble planting things as it will help to amend your soil!

AMARANTH: Easy to seed and flourishes in dry conditions. Good with sweet corn, its leaves provide shade giving the corn a rich, moist root run. This plant is a host to predatory ground beetles. The young leaves are tasty in salads!

ANISE: Liquorice flavoured herb, good host for predatory wasps which prey on aphids and may potentially deter aphids from your plants. Deters pests from brassicas by camouflaging their odour. Improves the vigor of any plants growing near it. This is a good plant to have near coriander.

BASIL: Plant with tomatoes to improve growth and flavor. Basil also does well with peppers, oregano, asparagus and petunias. Basil can be helpful in repelling thrips. It is said to repel flies and mosquitoes, so perfect for your picnic table! Do not plant near rue or sage.

BEANS: All beans enrich the soil with nitrogen fixed form the air, improving the conditions for whatever crop you plant after the beans are finished. They are good company for carrots, celery, chards, corn, eggplant, peas, potatoes, brassicas, beets, radish, strawberry and cucumbers. Beans are great for heavy nitrogen users like corn and grain plants because the nitrogen used up by the corn and grains are replaced at the end of the season when the bean plants die back. French Haricot beans, sweet corn and melons are a good combo. Summer savory deters bean beetles and improves growth and flavour. Keep beans away from the alliums (onions). Growing tip: Do not allow beans to mature on the plant, or it will stop producing, and do not pick beans or cultivate when they are wet, or it will spread viral diseases.

BEET: Good for adding minerals to the soil. The leaves are composed of 25% magnesium making them a valuable addition to the compost pile if you don’t care to eat them. Beets are also beneficial to beans with the exception of runner beans (runner or pole beans and beets stunt each other’s growth). Companions for beets are lettuce, onions and brassicas. Beets and kohlrabi grow perfectly together. Beets are helped by garlic and mints. Garlic improves growth and flavor. Rather than planting invasive mints around beets use your mint clippings as a mulch.

BORAGE: One of my favourite herbs because of its beautiful blue flowers!! Companion plant for tomatoes, squash, strawberries and most plants. Deters tomato hornworms and cabbage worms. It is also one of the best bee and wasp attracting plants! Adds trace minerals to the soil and a good addition the compost pile. The leaves contain vitamin C and are rich in calcium, potassium and mineral salts. Borage may benefit any plant it is growing next to via increasing resistance to pests and disease. It also makes a nice mulch for most plants. Borage and strawberries help each other and strawberry farmers always set a few plants in their beds to enhance the fruits flavour and yield. Plant near tomatoes to improve growth and disease resistance. After you have planted this annual once it will self seed. Borage flowers are edible.

BRASSICA: Benefit from chamomile, peppermint, dill, sage, and rosemary. They need rich soil with plenty of lime to flourish. Avoid planting with mustards, tomatoes, and  peppers.

BROCCOLI: Companions plants include Basil, Bush Beans, Cucumber, Dill, Garlic, Hyssop, Lettuce, Marigold, Mint, Nasturtium, Onion, Potato, Radish, Rosemary, Sage, Thyme and Tomato. Celery, onions and potatoes improve broccolis’ flavour when planted near it. Broccoli loves plenty of calcium. Pairing it with plants that need little calcium is a good combination such as nasturtiums and beets. Put the nasturtiums right under the broccoli plants. Herbs such as rosemary, dill and sage help repel pests with their distinct aromas. Do not plant near Grapes, strawberries, mustards and rue.

CABBAGE: Celery, dill, onions and potatoes are good companion plants. Celery improves growth and health. Clover interplanted with cabbage has been shown to reduce the native cabbage aphid and cabbageworm populations by interfering with the colonization of the pests and increasing the number of predatory ground beetles.  Chamomile planted with cabbage promotes growth and flavour. Cabbage does not get along with strawberries, tomatoes, peppers, eggplants, rue, grapes, lettuce and pole beans.

CARROTS: Leaf lettuce, onions and tomatoes are companion plants. Plant dill and parsnips away from carrots. Flax produces an oil that may protect root vegetables like carrots from some pests. Tomato plants can stunt the growth of your carrots but the carrots will still be of good flavor.

CATNIP: Deters flea beetles, aphids, Japanese beetles, squash bugs, ants and weevils. Fresh catnip steeped in water and sprinkled on plants will drive away flea beetles. It not just good for your cats!!!! Try planting catnip near reoccurring ant hills as a deterrent.

CELERY:  Bean, cabbage family, leek, onion, spinach and tomato are companions as well as these flowers: cosmos, daisies and snapdragons. Do not plant near Corn, Irish potato and aster flowers. Carrots can be infected with aster yellow disease from asters.

CHAMOMILE, GERMAN:  Improves flavour of cabbages, cucumbers and onions. Host to hoverflies and wasps. Accumulates calcium, potassium and sulphur, later returning them to the soil. Increases oil production from herbs. Roman chamomile is a low growing perennial that will tolerate almost any soil conditions. Growing chamomile of any type is considered a tonic for anything you grow in the garden.

CHARDS: Bean, cabbage family, tomato, onion and roses are companion plants. Don’t overlook chard’s value as an ornamental plant in flower beds or wherever you have room for it. Don’t grow chard near squashes, melons, cucumbers, pumpkins, corn or herbs.

CHIVES: Improves growth and flavor of carrots and tomatoes. Companion plant to apples, carrots, tomatoes, brassica (broccoli, cabbage, mustard, etc) and many others. Help to keep aphids away from tomatoes, mums and sunflowers. Chives may drive away Japanese beetles and carrot rust fly. Planted among apple trees it helps prevent scab and among roses it prevents black spot. It will take 2 years before the plants will prevent these 2 diseases though. A tea of chives may be used on cucumbers and gooseberries to prevent downy  and powdery mildews. Avoid planting near beans and peas.

CHRYSANTHEMUMS: C. coccineum kills root nematodes. (the bad ones) It’s flowers along with those of C. cineraruaefolium have been used as botanical pesticides for centuries. (i.e. pyrethrum) White flowering chrysanthemums repel Japanese beetles. Repels harmful insects such as aphids, spider mites and potato beetle. A tea from this can be used as a spray for spider mites.

CORN: Amaranth, beans, cucumber, white geranium, lamb’s quarters, melons, morning glory, parsley, peanuts, peas, potato, pumpkin, soybeans, squash and sunflower are all companion plants. A classic example is to grow climbing beans up corn while inter-planting pumpkins. The corn provides a natural trellis for the beans, pumpkins smother the weeds and helps corn roots retain moisture. Corn is a heavy feeder and the beans fix nitrogen from air into the soil however the beans do not feed the corn while it is growing. When the bean plants die back they return nitrogen to the soil that was used up by the corn.  Another interesting helper for corn is the weed Pig’s Thistle which raises nutrients from the subsoil to where the corn can reach them. Keep corn away from celery and tomato plants by at least 20 feet.

CUCUMBERS: Cucumbers are great to plant with corn and beans. The three plants like the same conditions: warmth, rich soil and plenty of moisture. Let the cucumbers grow up and over your corn plants. Cukes also do well with peas, beets, radishes and carrots. Radishes are a good deterrent against cucumber beetles. Dill planted with cucumbers helps by attracting beneficial predators. Nasturtium improves growth and flavor. Keep sage, potatoes and rue away from cucumbers.

DAHLIAS: These beautiful, tuberous annuals that can have up to dinner plate size flowers repel  bad nematodes!

DILL: Improves growth and health of cabbage. Do not plant near carrots, caraway, lavender or tomatoes. Best friend for lettuce. The flower heads of dill are one of the best nectar sources for beneficial insects in the garden attracting hoverflies, predatory wasps and many more. Repels aphids and spider mites to some degree. Also may repel the dreaded squash bug! (scatter some good size dill leaves on plants that are subject to squash bugs, like squash plants.) Dill goes well with lettuce, onions, cabbage, sweet corn and cucumbers. Dill does attract the tomato horn worm so it would be wise to plant it somewhere away from your tomato plants.

EGGPLANT: Plant with amaranth, beans, peas, spinach, tarragon, thyme and marigold. Eggplant does well with peppers as they like the same growing conditions.

ELDERBERRY: A spray made from the leaves can be used against aphids, carrot root fly and cucumber beetles. Put branches and leaves in mole runs to banish them. Elderberry leaves added to the compost pile speeds up the decomposing process.

FENNEL: Fennel is not friendly and is allelopathic to most garden plants, inhibiting growth or causing them to bolt. It actually kills many plants. Dill is the only thing you can plant with fennel. Other than that plant it by it’s self. On a positive note the foliage and flowers attract beneficial insects such as ladybugs, syrphid flies, tachninid flies, beneficial parasitoid wasps and hoverflies. Fennel is a good flea repellent. Dried fennel leaves provide additional flea repelling insurance when put inside the dog house or kennel.

FLAX: Plant with carrots, and potatoes. Flax contains tannin and linseed oils which may offend the Colorado potato bug. Flax is an annual from 1-4 feet tall with blue, red or white flowers that readily self sows.

FOUR-O’CLOCKS: Draws Japanese beetles like a magnet, which then dine on the foliage. The foliage is pure poison to them and they won’t live to have dessert! It is important to mention that Four O’clock are also poisonous to humans and animals. Please be careful where you plant them if you have children and pets. They are a beautiful annual plant growing from 2-3 feet high with a bushy growth form.

GARLIC: Plant near apple trees, pear trees, cucumbers, peas, lettuce, roses and celery to repel aphids.  Garlic accumulates sulfur: a naturally occurring fungicide which will help in the garden with disease prevention. Garlic is systemic in action as it is taken up by the plants through their pores and when garlic tea is used as a soil drench it is also taken up by the plant roots. It has value in offending codling moths, Japanese beetles, root maggots, snails, and carrot root fly. Researchers have observed that time-released garlic capsules planted at the bases of fruit trees actually kept deer away. Concentrated garlic sprays have been observed to repel and kill whiteflies, aphids and fungus gnats among others with as little as a 6-8% concentration! It is safe for use on orchids too.

GERANIUM: Repels cabbage worms and Japanese beetles, plant around grapes, roses, corn, tomatoes, peppers and cabbage. Geraniums help to distract beet leafhoppers, carrier of the curly top virus.

GRAPES: Hyssop is beneficial to grapes as are basil, beans, geraniums, oregano, clover, peas, or blackberries. Keep radishes and cabbage away from grapes. Planting clover increases the soil fertility for grapes. Chives with grapes help repel aphids. Plant your vines under Elm or Mulberry trees

HORSERADISH: Plant in containers in the potato patch to keep away Colorado potato bugs. Horseradish increases the disease resistance of potatoes. There are some very effective insect sprays that can be made with the root. Use the bottomless pot method to keep horseradish contained. Also repels Blister beetles. It has been observed that the root can yield anti-fungal properties when a tea is made from it

HYSSOP: Companion plant to cabbage and grapes, deters cabbage moths and flea beetles. Do not plant near radishes. Hyssop may be the number one preference among bees and some beekeepers rub the hive with it to encourage the bees to keep to their home. It is not as invasive as other members of the mint family making it safer for interplanting.

KELP: When used in a powder mixture or tea as a spray, this versatile sea herb will not only repel insects but feed the vegetables. In particular we have observed that kelp foliar sprays keep aphids and Japanese beetles away when used as a spray every 8 days before and during infestation times. If you have access to seaweed, use it as a mulch to keep slugs away.

KOHLRABI: May be planted with cucumber, mint, onion, oregano, sage, chives and thyme. Kohlrabi and beets are perfect to grow with one another! Do not plant kohlrabi with pole beans, pepper, strawberry or tomatoes.

LAMIUM: This will repel potato bugs- a big problem for many gardeners!

LARKSPUR: An annual member of the Delphinium family, larkspur will attract Japanese beetles. They dine and die! Larkspur is poisonous to humans too.

LAVENDER: Repels fleas and moths. Prolific flowering lavender nourishes many nectar feeding and beneficial insects. Lavenders can protect nearby plants from insects such as whitefly, and lavender planted under and near fruit trees can deter codling moth. Use dried sprigs of lavender to repel moths. Start plants in winter from cuttings, setting out in spring.

LEEKS: Use leeks near apple trees, carrots, celery and onions which will improve their growth. Leeks also repel carrot flies. Avoid planting near legumes.

LEMON BALM: Sprinkle throughout the garden in an herbal powder mixture to deter many bugs. Lemon balm has citronella compounds that make this work: crush and rub the leaves on your skin to keep mosquitoes away! Use to ward off squash bugs!

LETTUCE: Does well with beets, broccoli, bush beans, pole beans, carrots, cucumbers, onion, radish and strawberries. It grows happily in the shade under young sunflowers. Dill and lettuce are a perfect pair. Keep lettuce away from cabbage, as it is a deterrent to the growth and flavour of lettuce.

LOVAGE: Improves flavour and health of most plants. Good habitat for ground beetles. A large plant, use one planted as a backdrop. Similar to celery in flavour.

MARIGOLDS: (Calendula): Given a lot of credit as a pest deterrent. Keeps soil free of bad nematodes; supposed to discourage many insects. Plant freely throughout the garden. The marigolds you choose must be a scented variety for them to work. One down side is that marigolds do attract spider mites and slugs.

French Marigold (T. patula) has roots that exude a substance which spreads in their immediate vicinity killing nematodes. For nematode control you want to plant dense areas of them. There have been some studies done that proved this nematode killing effect lasted for several years after the plants died back. These marigolds also help to deter whiteflies when planted around tomatoes and can be used in greenhouses for the same purpose. Whiteflies hate the smell of marigolds. Do not plant French marigolds next to bean plants.

Mexican marigold (T.  minuta) is the most powerful of the insect repelling marigolds and may also overwhelm weed roots such as bind weed! It is said to repel the Mexican bean beetle and wild bunnies! Be careful it can have an herbicidal effect on some plants like beans and cabbage.

MARJORAM: As a companion plant it improves the flavour of vegetables and herbs. Sweet marjoram is the most commonly grown type.

MELONS: Companions: Corn, pumpkin, radish and squash. Other suggested helpers for melons are: Marigold to deter beetles, nasturtium to deter bugs and beetles. Oregano provides general pest protection.

MINT: Deters white cabbage moths, ants, rodents, flea beetles, fleas, aphids and improves the health of cabbage and  tomatoes. Use cuttings as a mulch around members of the brassica family. Mint flowers attract hoverflies and predatory wasps. Earthworms are quite attracted to mint plantings. Be careful where you plant it as mint is an incredibly invasive perennial. We have found that placing peppermint cuttings (fresh or dried) where mice are a problem is very effective in driving them off!

MORNING GLORIES: They attract hoverflies. If you want a fast growing annual vine to cover something up, morning glory is an excellent choice.

NASTURTIUMS: Nasturtium is an excellent companion for many plants. It is a companion to radishes, cabbage family plants (cabbage, collards, cauliflower, kale, kohlrabi, broccoli and mustards), deterring aphids, squash bugs, and striped pumpkin beetles, and improving growth and flavour. Plant as a barrier around tomatoes, cabbage, cucumbers, and under fruit trees. Deters woolly aphids, whiteflies, cucumber beetles and other pests of the cucurbit family. Great trap crop for aphids (in particular the black aphids) which it does attract, especially the yellow flowering varieties. It likes poor soil with low moisture and no fertilizer. Keeping that in mind there is no reason not to set potted nasturtiums among your garden beds. It has been the practice of some fruit growers that planting nasturtiums every year in the root zone of fruit trees allow the trees to take up the pungent odour of the plants and repel bugs. Studies say it is among the best at attracting predatory insects. It has no taste effect on the fruit. A nice variety to grow is Alaska which has attractive green and white variegated leaves. The leaves, flowers and seeds of nasturtiums are all edible and wonderful in salads!

ONIONS: Planting chamomile and summer savory with onions improves their flavour. Other companions are  carrot, leek, beets, kohlrabi, strawberries, brassicas, dill, lettuce and tomatoes. Intercropping onions and leeks with your carrots confuses the carrot and onion flies! Onions planted with strawberries help the berries fight disease. Keep onions away from peas and asparagus.

OPAL BASIL: An annual herb that is pretty, tasty and said to repel hornworms! Like the other basils it also does well with peppers, oregano, asparagus and petunias. Keep away from rue and sage.

OREGANO: Can be used with most crops but especially good for cabbage. Plant near broccoli, cabbage and cauliflower to repel cabbage butterfly and near cucumbers to repel cucumber beetle. Also benefits grapes.

PARSLEY: Allies: Asparagus, carrot, chives, onions, roses and tomato. Sprinkle the leaves on tomatoes, and asparagus. Use as a tea to ward off asparagus beetles. Attracts hoverflies. Let some go to seed to attract the tiny parasitic wasps and hoverflies. Parsley increases the fragrance of roses when planted around their base. Mint and parsley are enemies. Keep them well away from one another.

PARSNIPS: Plant them along with bush bean, garlic, marigolds, onion, pea, pepper, potato and radish. Parsnips like frequent, regular watering, so do not plant them with anything that prefers a drier soil. Like many root vegetables, parsnips taste their best when harvested after a few light frosts which causes them to convert their starch into sugars.

PEAS: Peas fix nitrogen in the soil. Plant next to corn. Companions for peas are bush beans, bole beans, carrots, celery, chicory, corn, cucumber, eggplant, parsley, early potato, radish, spinach, strawberry, sweet pepper, tomatoes and turnips. Do not plant peas with chives, gladiolus, grapes, late potatoes or onions.

PEPPERMINT: Repels white cabbage moths, aphids and flea beetles. It is the menthol content in mints that acts as an insect repellent. Bees and other good guys love it.

PEPPERS, BELL  (Sweet Peppers): Plant peppers near tomatoes, parsley, basil, geraniums, marjoram, lovage, petunia and carrots. Onions make an excellent companion plant for peppers. They do quite well with okra as it shelters them and protects the brittle stems from wind. Don’t plant them near fennel or kohlrabi. Peppers can double as ornamentals, so tuck some into flowerbeds and borders. Harvesting tip: The traditional bell pepper, for example, is harvested green, even though most varieties will mature red, orange, or yellow. Peppers can be harvested at any stage of growth, but their flavour doesn’t fully develop until maturity.

PEPPERS, HOT: Chili peppers have root exudates that prevent root rot and other Fusarium diseases. Plant anywhere you have these problems. While you should always plant chili peppers close together, providing shelter from the sun with other plants will help keep them from drying out and provide more humidity. Tomato plants, green peppers, and okra are good protection for them. Teas made from hot peppers can be useful as insect sprays. Hot peppers like to be grouped with cucumbers, eggplant, escarole, tomato, okra, Swiss chard and squash. Herbs to plant near them include: basils, oregano, parsley and rosemary. Never put them next to any beans, broccoli, cabbage, cauliflower, Brussels sprouts or fennel.

PETUNIAS: They repel the asparagus beetle, leafhoppers, certain aphids, tomato worms, Mexican bean beetles and general garden pests. A good companion to tomatoes, but plant everywhere. The leaves can be used in a tea to make a potent bug spray.

POTATO: Companions for potatoes are bush bean, members of the cabbage family, carrot, celery, corn, dead nettle, flax, horseradish, marigold, peas, petunia, onion and Tagetes marigold. Protect them from scab by putting comfrey leaves in with your potato sets at planting time. Horseradish, planted at the corners of the potato patch, provides general protection. Alyssum makes a perfect living mulch for them. Don’t plant these around potatoes: asparagus, cucumber, kohlrabi, pumpkin, rutabaga, squash family, sunflower, turnip and fennel. Keep potatoes and tomatoes apart as they both can get early and late blight, contaminating each other.

PUMPKINS: Pumpkin pals are corn, melon and squash. Marigold deters beetles. Nasturtium deters bugs, beetles. Oregano provides general pest protection. Again, dill may help repel those frustrating squash bugs.

PURSLANE: This edible weed makes good ground cover in the corn patch. Use the stems, leaves and seeds in stir-frys. Pickle the green seed pod for caper substitutes. If purslane is growing in your garden it means you have healthy, fertile soil!

RADISH: Companions for radishes are: beets, bush beans, pole beans, carrots, chervil, cucumber, lettuce, melons, nasturtium, parsnip, peas, spinach and members of the squash family.  Radishes may protect from squash borers. Radishes are a deterrent against cucumber beetles and rust flies. Chervil and nasturtium improve radish growth and flavor. Planting them around corn and letting them go to seed will also help fight corn borers. Chinese Daikon and Snow Belle radishes are favorites of flea beetles. Plant these at 6 to 12 inch intervals amongst broccoli. In one trial, this measurably reduced damage to broccoli. Radishes will lure leafminers away from spinach. The damage the leafminers do to radish leaves does not stop the radish roots from growing, a win-win situation. Keep radishes away from hyssop plants, cabbage, cauliflower, Brussels sprouts and turnips. Radishes are a good indicator of calcium levels in the soil. If you radish grows and only produces a stringy root you need calcium.

RHUBARB: A good companion to all brassicas. Try planting cabbage and broccoli plants near your rhubarb patch watch them thrive. Rhubarb protects beans against black fly. Some other interesting companions for rhubarb are the beautiful columbine flowers, garlic, onion and roses! It helps deter red spider mites from the columbines. A spray made from boiled rhubarb leaves, which contain the poison oxalic acid may be used to prevent blackspot on roses and as an aphicide.

ROSEMARY: Companion plant to cabbage, beans, carrots and sage. Deters cabbage moths, bean beetles, and carrot flies. Use cuttings to place by the crowns of carrots for carrot flies. Overwinter rosemary as houseplants or take cuttings.

RUE: Deters aphids, fish moths, flea beetle, onion maggot, slugs, snails, flies and Japanese beetles in roses and raspberries. Companions for rue are roses, fruits (in particular figs), raspberries and lavender. To make it even more effective with Japanese beetles: crush a few leaves to release the smell. Has helped repel cats. You should not plant rue near cucumbers, cabbage, basil or sage. A pretty perennial with bluish-gray leaves. May be grown indoors in a sunny window. Rue may cause skin irritation in some individual

SAGE: Use as a companion plant with broccoli, cauliflower, rosemary, cabbage, and carrots to deter cabbage moths, beetles, black flea beetles and carrot flies. Do not plant near cucumbers, onions or rue. Sage repels cabbage moths and black flea beetles. Allowing sage to flower will also attract many beneficial insects and the flowers are pretty. There are some very striking varieties of sage with variegated foliage that can be used for their ornamental as well as practical qualities.

SPINACH: Plant with peas and beans as they provide natural shade for the spinach. Gets along with cabbage, cauliflower, celery, eggplant, onion, peas, strawberries and fava bean. Plant spinach with squash. It’s a good use of space because by the time squash plants start to get big the spinach is ready to bolt.

SOYBEANS: They add nitrogen to the soil making them a good companion to corn. They repel chinch bugs and Japanese beetles.

SQUASH: Companions: Beans, corn, cucumbers, icicle radishes, melon, mint, onions and pumpkin. Helpers: Borage deters worms, improves growth and flavor. Marigolds deters beetle. Nasturtium deters squash bugs and beetles. Oregano provides general pest protection. Dill may repel the squash bug that will kill your squash vines. Generously scatter the dill leaves on your squash plants. Keep squash away from potatoes.

SWEET POTATOES: Sweet potatoes are not the same as regular potatoes. They are a member of the morning glory family. “Regular” potatoes are a member of the Solanaceae family which is the same as tomatoes, peppers etc. Aromatic herbs such as dill, thyme, oregano etc. are some of the plants that work well with them. Summer savory helps to confuse and perhaps repel the sweet potato weevil. They do well with root crops: beets, parsnips and salsify. Bush beans and regular potatoes are companions to them also. Alyssum makes a perfect living mulch for them. A few, only a few, pole beans may be planted with them and left to grow on the ground with the potato vines. Keep them away from squash. The problem with sweet potatoes and squash is they will compete with each other as they both like to spread out. In fact that is the general problem with sweet potatoes- they take up so much room and need full sun. Another idea is to grow them in a container. For your reference: you could grow a single sweet potato plant in a box or tub that is at least 12″ high and 15″ wide. Use a light, porous soil mix. Place a stake or trellis in the center to support the vine which grow up and outwards.

STRAWBERRY: Friends are beans, borage, lettuce, onions, spinach and thyme. Foes: Cabbage, broccoli, Brussels sprouts, cauliflower and kohlrabi. Allies: Borage strengthens resistance to insects and disease. Thyme, as a border, deters worms.

SUMMER SAVORY: Plant with beans and onions to improve

SUNFLOWERS: Planting sunflowers with corn is said by some to increase the yield. Aphids a problem? Definitely plant a few sunflowers here and there in the garden. Step back and watch the ants herd the aphids onto them. The sunflowers are so tough that the aphids cause very little damage and you will have nice seed heads for the birds to enjoy. Sunflowers also attract hummingbirds which eat whiteflies. Talk about a symbiotic relationship!

SWEET ALYSSUM:  Direct seed or set out starts of sweet alyssum near plants that have been attacked by aphids in the past. Alyssum flowers attract hoverflies whose larva devour aphids. Another plus is their blooms draw bees to pollinate early blooming fruit trees.

TARRAGON: Plant throughout the garden, not many pests like this one. Recommended to enhance growth and flavor of vegetables.

THYME: Deters cabbage worms. Wooly thyme makes a wonderful groundcover. You may want to use the upright form of thyme in the garden rather than the groundcover types. Thyme is easy to grow from seeds or cuttings. Older woody plants should be divided in spring.

TOMATOES: Tomato allies are many: asparagus, basil, bean, carrots, celery, chive, cucumber, garlic, head lettuce, marigold, mint, nasturtium, onion, parsley, pea, pepper, marigold, pot marigold and sow thistle. One drawback with tomatoes and carrots: tomato plants can stunt the growth of your carrots but the carrots will still be of good flavor. Basil repels flies and mosquitoes, improves growth and flavor. Bee balm, chives and mint improve health and flavor. Borage deters tomato worm, improves growth and flavor. Dill, until mature, improves growth and health, mature dill retards tomato growth. Enemies: corn and tomato are attacked by the same worm. Kohlrabi stunts tomato growth. Keep potatoes and tomatoes apart as they both can get early and late blight contaminating each other. Keep dill, fennel, cabbage and cauliflower away from them. Don’t plant them under walnut trees as they will get walnut wilt: a disease that attacks tomatoes growing underneath these trees.

TURNIP: Peas are good companions for turnips due to their nitrogen fixing in the soil. Cabbage does well with turnips because of the turnip’s tendency to repel certain pests. Do not plant potatoes, radishes or other root vegetables near your turnips. These vegetables will compete for nutrients with the turnips and reduce crop size and yield. Other plants that do not do well with turnips are delphinium, larkspur and mustard.

Watermelon: May be planted in between hills of corn. Grow them with corn, nasturtiums, peas, sunflowers, squash, cucumbers, pumpkins and radishes. Nasturtium helps to deter bugs and beetles. Oregano provides general pest protection.

YARROW: Yarrow has insect repelling qualities and is an excellent natural fertilizer. A handful of yarrow leaves added to the compost pile really speeds things up. It also attracts predatory wasps and ladybugs to name just two. It may increase the essential oil content of herbs when planted among them.

ZINNIA: Pretty zinnias attract hummingbirds which eat whiteflies. Alternately the pastel varieties of zinnias can be used as a trap crop for Japanese beetles. All zinnias attract bees and other insect pollinators.

4 Responses to “Companion Planting for Pest Control”

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