Companion plants that grow well next to tomatoes
Tomatoes grow better when certain plants are nearby—they attract helpful insects, repel pests, improve soil, or straightforward use space without competing for water and nutrients. The best companions are basil, carrots, marigolds, parsley, borage, and nasturtiums. Each works differently: basil repels flies and improves flavor; carrots loosen soil without stealing nitrogen; marigolds trap pests meant for tomatoes; borage brings pollinators; nasturtiums act as a trap crop, drawing aphids away from your tomato plants.
The key is spacing and timing. Plant companions at the same time as your tomatoes or a few weeks before, so they are established by the time your tomato plant is large enough to shade them. Most companions should be planted 12 to 18 inches away from the tomato stem, far enough to avoid root competition but close enough to affect pest and pollinator activity in the area.
Key Takeaways
- Basil, carrots, marigolds, parsley, borage, and nasturtiums are proven companions that reduce pests, improve pollination, or use garden space without competing with tomatoes for nutrients.
- Plant companions at the same time as tomatoes or a few weeks earlier so they are ready to work before your tomato plant grows large and shades the ground.
- Space companions 12 to 18 inches from the tomato stem to avoid root competition while keeping them close enough to affect pest activity.
- Avoid planting brassicas (cabbage, broccoli, kale), fennel, and potatoes near tomatoes because they compete for the same nutrients or attract the same pests.
Basil: flavor boost and pest control
Basil is the most popular tomato companion because it repels whiteflies, spider mites, and hornworms while also improving the flavor of nearby tomatoes. Plant basil 12 inches from the tomato stem in full sun. Basil needs the same watering schedule as tomatoes—moist but not waterlogged soil—so they are straightforward to manage together.
Pinch off basil flowers as they appear to encourage leaf growth and keep the plant compact. If you let basil flower, it will still work as a companion, but you will get fewer leaves to harvest. Basil is frost-sensitive, so plant it after your last frost date, at the same time or a week after your tomato transplants go in the ground.
Carrots and root vegetables that loosen soil
Carrots, beets, and radishes grow below ground while tomatoes grow above, so they do not compete for light or water. More importantly, their roots break up compacted soil, making it easier for tomato roots to spread and absorb nutrients. Plant carrots in rows around the base of tomato plants, spacing them 3 to 4 inches apart in the row and keeping the row at least 12 inches from the tomato stem.
Carrots take 60 to 80 days to mature, so plant them at the same time as your tomato transplants if you want to harvest them before the tomato plant gets very large. Radishes mature in 25 to 30 days and can be replanted every three weeks for a continuous harvest. Beets take 50 to 70 days and are less likely to be shaded out because their leaves stay lower to the ground than tomato foliage.
Marigolds and nasturtiums as trap crops
Marigolds and nasturtiums attract pests that would otherwise attack your tomatoes. Aphids, whiteflies, and spider mites prefer these plants to tomatoes, so they congregate on the companion plant instead. Plant marigolds 12 to 18 inches from the tomato stem in full sun. Nasturtiums can be planted closer—8 to 12 inches away—and they tolerate partial shade better than marigolds.
Check marigolds and nasturtiums weekly for pest buildup. If you see heavy infestations, spray them with water to knock pests off, or remove the plant entirely and compost it. This sounds counterintuitive, but removing a heavily infested trap crop is better than letting pests build up and spread to your tomatoes. Marigolds bloom all season and require minimal care; nasturtiums are more vigorous and may need pruning to keep them from shading tomatoes.
Herbs that improve pollination and soil
Borage and parsley attract bees and other pollinators, which improves tomato fruit set and yield. Borage has blue flowers that bees visit constantly; plant it 18 inches from the tomato stem in full sun. Borage is tall—up to 3 feet—so plant it on the north side of tomatoes so it does not shade them as it grows. Parsley is shorter and bushier; plant it 12 inches away in full sun or partial shade.
Both herbs are cold-hardy and can be planted before your last frost date. Borage self-seeds readily, so you may find seedlings appearing in your garden in future years. Parsley takes 70 to 90 days to reach full size, so plant it early in the season. Both are edible, so you can harvest leaves while they work as companions.
Plants to keep away from tomatoes
Brassicas—cabbage, broccoli, kale, and cauliflower—compete with tomatoes for nitrogen and potassium, so they should be planted in a different bed. Fennel releases chemicals into the soil that inhibit tomato growth; keep it at least 3 feet away or in a separate garden area. Potatoes are susceptible to the same diseases as tomatoes, particularly early blight and late blight, so planting them together increases the risk that disease will spread from one plant to the other.
Corn and tomatoes can grow together, but corn grows tall and may shade tomatoes in the afternoon. If you plant corn, position it on the north side of your tomato bed so morning and midday sun still reaches the plants. Avoid planting tomatoes near walnut trees; walnut roots release a chemical called juglone that is toxic to many plants, including tomatoes.
Spacing and timing for companion planting
The standard spacing rule is 12 to 18 inches between the tomato stem and the companion plant. This distance allows each plant to access water and nutrients without direct root competition, while keeping them close enough that pest-repelling or pollinator-attracting effects still work. Smaller companions like basil and parsley can be planted at 12 inches; larger ones like borage should be 18 inches away.
Timing matters because companions need to be established before your tomato plant grows large enough to shade them. Plant companions at the same time as your tomato transplants, or plant them 2 to 3 weeks earlier if you are starting them from seed. Fast-growing companions like radishes can be planted later in the season as earlier crops are harvested. Check the days-to-maturity on the seed packet and count backward from your expected tomato harvest date to know when to plant.
Frequently Asked Questions
Can I plant tomatoes and basil in the same pot?
Yes, if the pot is at least 18 inches deep and 24 inches wide. Plant the tomato in the center and basil around the edge, 12 inches from the stem. Water consistently because container soil dries faster than garden soil. A single large pot works better than two small ones because the soil stays more evenly moist.
What if I plant companions too close to tomatoes?
They will compete for water and nutrients, and the tomato plant may grow slower or produce less fruit. The companion plant may also be shaded out and die. If you realize spacing is wrong after planting, thin or transplant the companion to the correct distance rather than leaving it too close.
Do I have to use companion plants?
No. Tomatoes grow fine alone with proper watering, sunlight, and soil. Companions reduce pest pressure and improve pollination, but they are not required. If your garden space is limited, focus on good tomato care instead of adding companions.
Can I plant multiple companions around one tomato?
Yes, as long as you space them correctly. A typical setup is basil on one side, marigolds on another, and carrots in a row around the base. Keep each companion 12 to 18 inches from the tomato stem and space companions 18 to 24 inches apart from each other so they do not shade one another.
When should I remove companion plants?
Remove trap crops like nasturtiums if they become heavily infested with pests. Harvest herbs like basil and parsley as needed throughout the season. Root vegetables like carrots and radishes are harvested when mature. Borage and marigolds can stay in the garden all season and will continue to bloom and attract pollinators until frost.