Companion Planting Combinations That Actually Work

This is one of the most widely used pairings in home vegetable gardens. Basil is thought to repel aphids, thrips, and certain flies that commonly trouble tomato plants. The strong aromatic oils in basil leaves may also help mask the scent of tomatoes from pests. Plant basil around the base of tomato plants, roughly 12 inches away to avoid root competition. As a bonus, you'll have fresh basil within easy reach of your tomatoes at harvest — a practical kitchen benefit that doubles the value of the space.

Used by Indigenous farmers across North America for centuries, this trio works as a self-supporting system. Corn grows tall and provides a natural pole for beans to climb. Beans are legumes, meaning they fix atmospheric nitrogen back into the soil — a direct fertility benefit for neighboring plants. Squash spreads along the ground, shading out weeds and retaining moisture with its broad leaves. Plant corn first, then add beans once the stalks are several inches tall, and tuck squash seedlings at the edges. This combination makes excellent use of vertical and horizontal space simultaneously.

French marigolds (Tagetes patula) are among the most researched companion plants in home gardening. They produce a root secretion that has been shown in some studies to suppress soil-dwelling nematodes — microscopic pests that damage plant roots. Above ground, their scent is believed to deter whiteflies, aphids, and certain beetles. Plant them as a border around vegetable beds or tuck them between rows. They're inexpensive to grow from seed, and their bright blooms also attract pollinators. One important note: while marigolds are broadly helpful, they can inhibit the germination of beans if planted too close.

These two deter each other's most damaging pests through scent. Onions (and their relatives like leeks and chives) release sulfur compounds that are believed to confuse and repel carrot flies. Carrots, in turn, may help deter onion flies. Interplanting them in alternating rows keeps pest populations lower than growing either crop in a solid block. Both are compact growers, making this pairing particularly well-suited to smaller garden beds. It also works well in containers — a strategy explored further in our honest look at container gardening.

Nasturtiums are a classic trap crop — they attract aphids away from cucumbers and other nearby vegetables, concentrating pest pressure on a plant that can tolerate it and is easily removed or replaced. They also attract predatory insects like hoverflies whose larvae feed on aphids. Beyond pest management, nasturtiums are edible themselves: both the flowers and leaves are usable in salads, which means they contribute food as well as function. Plant them at the edges of your cucumber bed or along the perimeter of the garden. Avoid planting nasturtiums directly next to brassicas like cabbage or broccoli, as they can encourage certain caterpillars in that context.

Lettuce is a cool-season crop that bolts (goes to seed prematurely) when exposed to intense summer heat. Planting it in the shade of taller crops like tomatoes, pole beans, or trellised cucumbers gives it protection during the warmer parts of the day, extending your harvest window by several weeks. This arrangement also makes use of otherwise wasted space beneath tall plants. Choose loose-leaf varieties for the best results in partial shade. Be mindful of watering — taller plants can create dry zones in their footprint, so check soil moisture in shaded areas more carefully than you might expect.