11 Plant Combos You Should Grow Side-by-Side

"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 cukes up a trellis, and lets the nasturtiums, which have a unique scent that seems to repel pests, grow in a colorful tumble underneath.

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.

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.

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.

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.

"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.

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.

Some gardeners believe basil improves the flavor 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.

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.

Plants with a strong odor 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 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!