What Are the Best Companion Plants for Tomatoes?
Tomatoes grow best with marigolds, parsley, dill, sweet alyssum and lettuce. 14 plants in our chart pair well with tomatoes, mostly by deterring or trapping pests and attracting pollinators and beneficial insects; 4 of those pairings are research-supported.
| Plant | Why | Evidence |
|---|---|---|
| MarigoldsPest control | French marigold roots release a compound that suppresses root-knot nematodes, which also attack tomatoes. The effect is documented, but it is strongest when marigolds grow densely in the bed for a season before tomatoes; a few border plants do little. | Research-supported |
| ParsleyPollinators & beneficials | Flowering parsley provides nectar for hoverflies and tiny parasitic wasps that attack aphids and caterpillars on tomatoes; parsley flowers in its second year. | Research-supported |
| DillPollinators & beneficials | Flowering dill feeds hoverflies, lacewings and parasitic wasps that prey on tomato pests. Keep it a few feet away: tradition holds, without evidence, that mature dill slows tomato growth. | Research-supported |
| Sweet AlyssumPollinators & beneficials | Sweet alyssum's tiny flowers feed hoverflies and parasitic wasps; hoverfly larvae eat the aphids that attack tomatoes. | Research-supported |
| LettuceSupport & shade | Tomatoes shade lettuce in summer, which keeps it cooler and slows bolting; plant lettuce on the north or east side. | Practical |
| SpinachSpace & timing | Spinach sown in early spring is harvested before tomatoes fill out, so the same space produces two crops. | Practical |
| BasilPest control | Basil is the classic tomato partner. Its scent is said to deter thrips, whiteflies and hornworm moths, but trial results are limited and mixed; the pairing works mainly because both need the same sun, heat and water. | Traditional |
| BoragePollinators & beneficials | Borage flowers all summer and draws bees and predatory insects to the tomato bed; the claim that it repels tomato hornworms is anecdotal. | Traditional |
| CarrotsSpace & timing | Carrots root below tomatoes' spreading roots and tolerate their late-season shade. The popular idea that tomatoes and carrots help each other grow is folklore. | Traditional |
| ChivesPest control | Chives are traditionally planted around tomatoes to deter aphids; the evidence is anecdotal, but the clumps take almost no space. | Traditional |
| GarlicPest control | Garlic's sulfur compounds are said to repel aphids and spider mites from tomatoes; field evidence is thin, but garlic harvested in early summer frees up space as tomatoes grow. | Traditional |
| NasturtiumsPest control | Nasturtiums act as a sacrificial trap for aphids and cover bare soil under staked tomatoes; trap-crop results vary. | Traditional |
| AsparagusPest control | Tomatoes are said to repel asparagus beetles and asparagus to deter nematodes that attack tomatoes. Neither claim has solid evidence, but tomatoes use the bed's summer space after the spear harvest. | Traditional |
| MintPest control | Potted mint near tomatoes is a traditional aphid deterrent; evidence is inconsistent. Never plant mint loose in the bed. | Traditional |
Good companion plants for tomatoes, strongest evidence first.
What Should You Not Plant With Tomatoes?
Don't plant tomatoes near potatoes, corn, black walnut, strawberries and fennel. The conflicts come mainly from competition for space, light or water and shared pests and diseases; 4 of the 9 are research-supported and the rest are practical or traditional rules.
| Plant | Why | Evidence |
|---|---|---|
| PotatoesShared pests & disease | Both are nightshades that share late blight, early blight, Verticillium wilt and Colorado potato beetles; spores and pests move from one crop to the other. | Research-supported |
| CornShared pests & disease | The corn earworm and the tomato fruitworm are the same insect (Helicoverpa zea); a corn patch next to tomatoes can raise fruitworm numbers. | Research-supported |
| Black WalnutAllelopathy | Tomatoes are among the most juglone-sensitive plants: black walnut roots release juglone, and tomatoes wilt and die within the tree's root zone. | Research-supported |
| StrawberriesShared pests & disease | Tomatoes host Verticillium wilt, a soil fungus that survives for years and kills strawberry plants. Don't grow strawberries near or after tomatoes. | Research-supported |
| FennelAllelopathy | Fennel is widely said to stunt tomatoes. Fennel extracts inhibit germination in lab tests, but garden-scale evidence is thin; its size and water use are the practical reasons to keep it apart. | Traditional |
| CabbageCompetition | Both are heavy feeders that compete for nitrogen. The old rule to keep tomatoes and cabbage-family crops apart rests on competition, not proven harm — some growers even report fewer diamondback moths near tomatoes. | Traditional |
| BroccoliCompetition | Both are heavy feeders that compete for nitrogen. The old rule to keep tomatoes and cabbage-family crops apart rests on competition, not proven harm — some growers even report fewer diamondback moths near tomatoes. | Traditional |
| CauliflowerCompetition | Both are heavy feeders that compete for nitrogen. The old rule to keep tomatoes and cabbage-family crops apart rests on competition, not proven harm — some growers even report fewer diamondback moths near tomatoes. | Traditional |
| KaleCompetition | Both are heavy feeders that compete for nitrogen. The old rule to keep tomatoes and cabbage-family crops apart rests on competition, not proven harm — some growers even report fewer diamondback moths near tomatoes. | Traditional |
Plants to keep away from tomatoes.
Which Tomato Companion Claims Are Backed by Research?
8 of the 23 tomato pairings in our data are research-supported: marigolds, parsley, dill, sweet alyssum, potatoes, corn, black walnut and strawberries. Of the rest, 2 rest on practical horticulture and 13 are traditional claims.
Research-supported pairings rest on documented biology: shared pathogens, pollination, nematode suppression or insects that feed on specific flowers. Practical pairings are plain logic about space, shade and timing. Traditional companions such as basil, borage, carrots and chives are harmless to grow with tomatoes, but don't rely on them for pest control — row covers, crop rotation and regular checks do more.
How Should You Plant Tomatoes With Companions?
Plant tomatoes about 24 inches (60 cm) apart with basil or a ring of French marigolds between plants, lettuce or spinach on the north or east side where tomato shade falls, and sweet alyssum or nasturtiums as ground cover. Grow potatoes in a different bed and rotate so neither crop follows the other.
Companions still need room of their own, so work out how many tomatoes and partner plants fit in a bed with the plant spacing calculator. Planting dates for tomatoes and their companions follow your local spring and fall frost dates, so warm-season partners go in together after the last spring frost, while cool-season fillers such as spinach and radishes use the bed before then.
Watering, feeding, light and harvest timing for tomatoes are covered in the tomato plant care guide.
Which Crops Share Companions With Tomatoes?
Peppers, basil and eggplant share companion plants or growing conditions with tomatoes, so their companion guides help plan the same bed or rotation.
- The guide to companion plants for peppers overlaps with this one: both crops grow well with marigolds, sweet alyssum and lettuce; as members of the same plant family, the two should rotate together.
- The guide to companion plants for basil overlaps with this one: both crops grow well with parsley, chives and asparagus, and basil is a good companion for tomatoes too.
- The guide to companion plants for eggplant overlaps with this one: both crops grow well with marigolds, sweet alyssum and lettuce; as members of the same plant family, the two should rotate together.
To check tomatoes against every other plant at once, or test a whole bed plan, use the companion planting chart and garden checker.
Frequently Asked Questions
- What is the best companion plant for tomatoes?
- Marigolds are one of the best-supported companions for tomatoes. French marigold roots release a compound that suppresses root-knot nematodes, which also attack tomatoes. The effect is documented, but it is strongest when marigolds grow densely in the bed for a season before tomatoes; a few border plants do little.
- What should you not plant with tomatoes?
- Avoid planting tomatoes near potatoes, corn, black walnut, strawberries, fennel and cabbage. The most important conflict is with potatoes: Both are nightshades that share late blight, early blight, Verticillium wilt and Colorado potato beetles; spores and pests move from one crop to the other.
- Can you plant tomatoes and peppers together?
- Yes, tomatoes and peppers can share a bed; neither is known to help or harm the other. Both belong to the nightshade family (Solanaceae), so they share pests and diseases — rotate them together and don't follow one with the other.
- Does companion planting really work for tomatoes?
- Partly. 8 of the 23 tomato pairings in our data are backed by research, 2 are practical space or timing rules, and 13 are traditional. Flowers that feed beneficial insects and separating crops that share diseases have the strongest evidence.
- Is it good to plant basil with tomatoes?
- Basil is a good tomato companion because both need full sun, warm soil and even watering, and basil fits between staked tomato plants. Claims that basil improves tomato flavor or reliably repels hornworms and whiteflies are traditional; trial results are limited and mixed.
Companion data: PlantoScan's own editorial compilation, written from general horticultural knowledge, plant pathology and published intercropping research. Evidence labels are our editorial judgment; results vary with climate, soil, variety and pest pressure.