Companion Planting for Tomatoes: What to Plant (and Avoid)
- companion-planting
- tomatoes
Companion planting is the practice of growing certain plants near each other for mutual benefit — better pest control, pollination, flavor, or use of space. Tomatoes happen to be one of the best-studied crops for it. Here’s what actually earns a spot next to your tomatoes, and what to keep at a distance.
Best companion plants for tomatoes
Basil
The classic pairing. Basil’s strong scent helps mask tomatoes from pests like thrips and whiteflies, and its flowers draw in pollinators. Gardeners have claimed for generations that basil improves tomato flavor — the jury’s out on that, but the pest and pollinator benefits are real. Bonus: they love the same warm, sunny, well-watered conditions.
Marigolds
French marigolds are one of the few companions with solid research behind them. Their roots release compounds that suppress root-knot nematodes — microscopic soil pests that damage tomato roots. Plant them as a border and let them do quiet work underground.
Carrots, lettuce & other low growers
Tomatoes grow tall and open; carrots, lettuce, and spinach grow low. Tucking these beneath your tomatoes uses vertical space efficiently, and the tomato canopy gives cool-season greens welcome afternoon shade in summer.
Nasturtiums
These act as a trap crop — aphids prefer nasturtiums and cluster on them instead of your tomatoes, making the pests easy to spot and remove. They also attract predatory insects.
Borage
A pollinator magnet that’s also said to deter tomato hornworms. Its blue flowers bring in bees, and it’s a low-effort addition to any tomato bed.
What NOT to plant near tomatoes
- Brassicas (cabbage, broccoli, kale, cauliflower). Heavy feeders that compete hard for the same nutrients, and they prefer cooler conditions.
- Fennel. Releases compounds that inhibit the growth of many nearby plants, tomatoes included. Give it its own corner.
- Potatoes. Both are in the nightshade family and share diseases like early and late blight. Planting them together lets disease jump easily between them.
- Corn. The corn earworm and tomato fruitworm are the same pest — grouping these crops invites a bigger infestation.
Why companion planting works
Three mechanisms do most of the heavy lifting:
- Scent masking & confusion. Strongly aromatic plants make it harder for pests to locate their target crop by smell.
- Trap cropping. A more attractive plant lures pests away from the one you care about.
- Beneficial habitat. Flowering companions feed pollinators and predatory insects that patrol your beds for free.
None of it replaces good basics — healthy soil, proper spacing, and consistent watering — but it stacks the odds in your favor.
A simple tomato companion layout
Try this in a raised bed:
| Position | Plant | Why |
|---|---|---|
| Center | Tomatoes | Main crop |
| Interplanted | Basil | Pest masking, pollinators |
| Border | Marigolds | Nematode suppression |
| Edges | Nasturtiums | Aphid trap crop |
| Beneath | Lettuce | Uses shade, saves space |
Keep brassicas, fennel, potatoes, and corn in a separate bed.
The bottom line
Pair tomatoes with basil, marigolds, nasturtiums, and low-growing greens; keep them away from brassicas, fennel, potatoes, and corn. It’s a low-cost way to cut pest pressure and get more out of every square foot.
Garden Pro Planner includes companion-planting guidance and advanced filtering across 225+ plants, so you can design beds that work together — right down to which plants are pet-safe.