By Cathy Krar, Master Gardener, SCMG
Companion planting is about natural balance and growing plants together that can be mutually beneficial. Planting your vegetable garden with plants that repel pests will help increase yields, reduce disease, and limit the insects that ravage your vegetable crops.
Positioning plants that problem insects detest next to plants that they love is a good defensive move. A strongly scented companion plant can confuse a pest looking for a host. Not only that, but some of the companion plants also have antibacterial and antifungal properties.
Don’t use pesticides! They kill the good guys as well as the bad. It is your beneficial insects like hoverflies, praying mantis, lacewing, ladybugs, and parasitic wasps that do all the work in your garden. Be observant and get to know what the larvae of your insects look like to improve your pest control methods. Give them encouragement by planting “flowery friends” in the garden.
Melons and squash are friendly with dill, fennel, and parsley. My grandmother knew that flowering herbs were a magnet for pollinators like butterflies and hummingbirds, and other insect allies that go to town in providing protection for your garden.
Swiss chard and sweet alyssum are great pals. If you put alyssum anywhere aphids are a problem, the larvae of hoverflies help to control the aphid population.
Parasitic Wasp laying eggs in predator larva. She is one of your best garden friends.
The bloated larvae seen on this leaf is actually evidence that a parasite wasp has injected its eggs into aphid larvae.
Grandma was practicing polyculture, long before it became fashionable. Instead of planting one single crop in each area, she planted at least three. Her practice was to plant: a vegetable, an herb, and a flower in close proximity.
The indigenous people planted the 3 sisters: pole beans, corn, pumpkin, and squash. The beans climb the cornstalk for vertical support and convert atmospheric nitrogen into a form that all three plants can use. The leaves of the pumpkin or squash reduce weeds and retain moisture. A wonderful symbiotic relationship, a practice that has endured for hundreds of years.
I learned that corn is prone to attack by a variety of worms that cause serious damage. Parsley is a way to protect corn crops as they attract wasps and tachinid flies. Until I fence in my garden, my corn is sacrificed to the whims of raccoons in the area.
Parsley is also a great friend of asparagus and peppers as it masks the odor of the host -seeking aphids and asparagus beetle. Asparagus is an earlier producing crop, planting lower growing parsley is an effective way to use that space.
The combination of calendula and broccoli is successful because the flowers create a sticky substance that attracts aphids and traps them there. As a bonus, ladybugs are also attracted, and they eat the aphids. A win-win match.
Lettuce and tomatoes or eggplant is a pairing known as “intercropping”, and proven effective. Tomatoes and eggplant grow taller and provide cool shade underneath, that lettuce prefers.
Radish and carrots don’t compete for mineral resources despite being root crops. Radishes mature faster (in as little as 5 weeks) and don’t grow deeply; while carrots have longer tap roots that need more time to mature.
Tomatoes planted with basil or cilantro work because the herbs have a strong odor that repels pests. And the flowers of these herbs are enticing to pollinators.
A great combination to plant with lettuce is chives or garlic. Aphids don’t like the smell of chives or garlic. And if you plant alyssum nearby, this will also attract the beneficial hoverflies and lacewings that happen to enjoy a meal of aphid.
Lady Bug Larva is one of the good guys! Get to know and recognize its larva. It doesn’t harm your plants, and grow up to eat over 5,000 aphids during their lifetime.
Roses and geraniums or chives make good friends. Beetles and aphids love our rose plants, so it is worth the effort to have friends with a strong odor or taste to act as sentry. Planting thyme near roses will help to keep away blackfly.
Cabbage and chamomile make good companions with Brassica plants like cabbage, Brussel sprouts, broccoli and cauliflower who are helped by the attraction of beneficial insects to chamomile. Once the growing season ends, chamomile can be chopped up and left to decompose to enrich your garden soil.
Parsnips and carrots, planted with alliums like onion, garlic, or leeks, are said to ward off carrot root flies; and the smell of carrots or parsnips deters leek moths. A mutually friendly relationship.
Lavender will attract many pollinators, and when planted near tomatoes and beans will increase bees, butterflies, and hoverflies. As an added benefit lavender further discourages pests to carrots and leeks.
Mint confuses flea beetles that enjoy laying their eggs on Brassicas. Just a word of caution, mints can spread by underground rhizomes. Since mint is such a vigorous grower, it might be better placed in a pot in the garden.
The planting of wormwood (Artemisia absinthium) keeps blackfly aphids from broad beans and other bean crops. While sage (Salvia officinalis) has a strong enough scent to confuse flea beetles from Brassicas, its scent is perfume to bees and hoverflies.
Hairy leafed borage planted near strawberries is said to improve their flavour and it too, is a magnet for pollinators.
Borage is also a good cover cop option because of the nutrients it returns to the soil. It is best planted in the spring and early summer, so that you get the benefit of the blooming blue star-shaped flowers.
In checking the reason onions don’t do well with peas, beans, sage, or asparagus, I found that it is largely due to chemical incompatibility and possible flavour contamination. Onions give off exudates or root secretions in the soil. This promotes the growth of its kin plants but is believed to stunt the growth of others. Since onions naturally repel aphids, Japanese beetles, rabbits, as well as cabbage loopers, worms and maggots … the best companions for onions are CABBAGE, broccoli, kale, Brussel sprouts, tomatoes, lettuce, peppers, eggplants, zucchini, potatoes, cucumber, and STRAWBERRIES!
This year I plan to use the vertical support of sunflower for the sprawl of cucumber, with nasturtium planted underneath to repel the pests. Some other suggestions for flower power could be alyssum, coreopsis, cosmos, lavender, lobelia, marigold, tansy, rudbeckia, scabiosa, yarrow, and zinnias.
So, grandma really did know best! She was onto something in making sense of successful planting combinations, working with Mother Nature in growing a healthy garden. She learned to rely on beneficial insects and pollinators to do all the hard work. And above all … Grandma didn’t use sprays.
