It’s part folklore, part science, but companion planting just may help your garden grow.
By Arricca Sansone
Step back in time to embrace some gardening wisdom your grandparents may have practiced: The concept of companion planting, or planting combinations of specific plants for their mutual benefit. “The theory behind companion planting is that certain plants may help each other take up nutrients, improve pest management or attract pollinators,” says Tom Maloney, horticulture educator for Penn State Extension. “Some research, such as how to attract beneficial insects like lacewings to the garden to fight pests, has been studied, so we know it’s effective. We’re still researching other aspects of companion planting.”
In the meantime, it certainly won’t hurt to try this common-sense companion planting:
Nasturtium + Cucumber
“For me, companion planting is about bringing pollinators and beneficial insects to your garden to improve biodiversity,” says Amy Stross, blogger at TenthAcreFarm.com and author of The Suburban Micro-Farm. Stross grows cucumbers up a trellis, and lets the nasturtiums, which have a unique scent that seems to repel pests, grow in a colourful tumble underneath.
Melons or Squash + Flowering Herbs
These are all vegetables that require pollinators to produce, so invite insect visitors into your garden by planting flowering herbs such as dill, fennel and parsley near melons and squash. “You won’t get any yield if you don’t have pollination for these veggies,” says Maloney.
Sweet Alyssum + Swiss Chard
Alyssum is an annual that’s easy to grow from seed in between rows of vegetables. “It’s a big attractor of hover flies, which are beneficial insects that control aphids,” says Stross. Plant pretty Swiss chard as a border, interspersed with these delicate low-growing flowers.
Corn + Pole Beans + Squash or Pumpkin
This Native American example of companion planting is often called the “Three Sisters.” Corn gives the beans a place to climb. Beans convert atmospheric nitrogen to a form the plants can use. The spreading leaves of squash or pumpkin create a living mulch that reduces weeds and holds moisture.
Calendula + Broccoli
These flowers exude a sticky substance on their stems that attract aphids and traps them there, says Stross. She finds that planting it next to her brassica crops, specifically broccoli, keeps the aphids off the broccoli. Plus, it brings in beneficial ladybugs to dine on the aphids.
Lettuce + Tomatoes or Eggplants
“Pairing plants with different growth habits together is referred to as ‘intercropping,’ and we do have some data to show it’s effective,” says Maloney. In this case, tomatoes and eggplant grow tall and eventually can shade cool season crops such as lettuce, which doesn’t like heat. This trick may extend your lettuce season slightly.
Radishes + Carrots
These two plants take up nutrients from different places in the soil so they aren’t competing for resources. Radishes mature quickly and don’t grow as deeply as carrots, which have a long tap root and take more days to mature, says Maloney.
Tomatoes + Basil or Cilantro/Coriander
Some gardeners believe basil improves the flavour of tomatoes, but it’s primarily planted because its strong scent may repel pests. Plus, if you let some of your basil or cilantro go to flower, it brings in the pollinators, says Stross.
Lettuce + Chives or Garlic
Aphids steer clear of smelly plants like chives or garlic, so try it near your lettuce. Or add alyssum nearby to bring in the beneficial insects, says Stross.
Roses + Geraniums or Chives
Plants with a strong odour or taste are said to discourage beetle and aphids. While there’s no guarantee it works, it’s certainly worth giving it a try to prevent roses from getting eaten by these pesky little bugs, which seemingly multiply overnight.
Chamomile + Cabbage
Chamomile brings in the beneficial insects for brassicas such as cabbage. In the fall, chop it up and toss on the bed to decompose, while leaving the roots intact to decay and enrich the soil, suggests Stross. “Maybe there’s not always a lot of scientific evidence behind some of these pairings, but just start trying and see what works,” says Stross. After all, experimentation is half the fun in the garden!