Plants that protect your garden
Marigolds
French marigolds (Tagetes patula) are the most battle-tested companion plant in vegetable gardening. A 2019 study from Newcastle University confirmed that marigolds planted alongside tomatoes significantly slowed whitefly population growth throughout the growing season. Their roots release compounds called thiophenes that are toxic to soil nematodes, and their bright blooms draw in ladybugs, parasitic wasps, and hoverflies — all of which devour common garden pests.
Basil
Basil is the classic tomato companion — and for good reason. Its strong scent deters aphids, tomato hornworms, whiteflies, and mosquitoes. Research has shown that rows of tall basil planted around tomatoes reduce hornworm damage. As a bonus, many gardeners swear that basil grown near tomatoes actually improves the flavor of the fruit. It's also one of the most useful herbs in the kitchen, so you get double the benefit from every plant.
Rosemary
Rosemary's powerful, resinous scent is too much for many garden pests. It's particularly effective at repelling cabbage moths — a serious problem for broccoli, kale, cauliflower, and Brussels sprouts. It also confuses carrot flies and deters bean beetles. Rosemary is a drought-tolerant perennial in warmer climates, meaning it keeps protecting your garden year after year with almost no maintenance.
Mint
Mint is a powerhouse pest repellent — its intense menthol scent deters aphids, ants, cabbage moths, carrot flies, and flea beetles. It works brilliantly near tomatoes, brassicas, and peas. The catch: mint is an aggressive spreader that will take over a raised bed if left unchecked. The solution is simple — grow mint in a pot and place it next to your bed, or sink the pot into the soil to contain the roots. You get all the pest protection with none of the takeover.
Thyme
Thyme is a low-growing, fragrant herb that earns its place in any raised bed. It repels whiteflies, cabbage loopers, and cabbage maggots, and its small flowers attract ladybugs that consume over 50 aphids per day. Thyme is drought-tolerant, easy to grow, and works beautifully as a border plant along the edges of a bed. It also happens to be one of the most versatile culinary herbs, so every plant does double duty.