Plant pairings can deter pests, increase yield, and reduce our reliance on chemicals

Diversity confuses insect pests who would have no trouble finding their favorite vegetable if it were presented in isolation like a sandwich on a plate.

Hull Community Garden
Different varieties of Huecheras grow around a birdbath. Hull Community Garden

Planning a vegetable garden is fun when it’s still too early to dig and plant. But if you want to be a real magician, consider using combinations this year that help plant neighbors thrive.

Many have been passed down by generations of farmers gardening long before modern chemicals. Nitrogen-fixing mosquito ferns have been grown with rice plants in China to help fertilize them for at least a thousand years. The most famous plant combination in the New World is called “The Three Sisters.” Native Americans have cultivated this trio of corn, beans, and squash since these wild native plants were first domesticated. The corn provides stalks for pole beans to climb, while the beans take nitrogen from the air and make it accessible to other plant roots in the soil. Meanwhile, an understory of sprawling squash vines has prickly stems that thwart corn-loving animals like raccoons, while keeping the soil more moist and cool.


Companion planting is getting a closer look with the rise of organic farming, because sometimes it can replace harmful chemicals by repelling pests, while attracting beneficial insects and pollinators. Studies show that nasturtium and marigolds help reduce cucumber beetles and squash bugs and that zinnias attract ladybugs that eat aphids. So dot your vegetable garden with cutting flowers.

Members of the dill family, including parsley, carrots, and Queen Anne’s lace attract beneficial insects partly because their flat, horizontal flowers provide good landing zones, said Marie Chieppo, an ecological landscape designer and consultant who writes for the Leaflet publication of the Massachusetts Horticultural Society.

Plant shallow-rooted beans and chard together because they both need more frequent irrigation. (And tomatoes deter asparagus beetles, too.) But combine deep-rooted vegetables such as tomatoes and asparagus because they both need deeper but less frequent watering.

There are plenty of lists of what plants to grow, or not grow, together. For example, tomatoes prefer to live next to basil, parsley, marigolds, carrots, onions, and peppers. But dill attracts tomato hornworms, so plant the herb far from your tomatoes as a decoy. The smell of onions repels carrot-root fly, while the smell of carrots repels onion fly, so this is a good combination. For more suggestions, visit


If all this sounds too complicated, just mimic nature by mixing a lot of different plants together. Growing just one type, like an acre of spinach or suburban lawn, will attract a lot more pests and diseases than a complex plant community that mingles odors, heights, and colors. Diversity confuses insect pests who would have no trouble finding their favorite vegetable if it were presented in isolation like a sandwich on a plate.

While you’re at it, instead of eradicating clover in grass with herbicides, encourage it in your lawns. It provides both free nitrogen for lawns and pollen for pollinators. “Clover is fantastic!” Chieppo said. She urges people to look for it in the ingredient labels on alternative lawn seed mixes.

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