Companion planting is one of the most rewarding techniques in organic gardening, and tomatoes are perhaps the most social plants in your garden.

By strategically choosing the right neighbours for your tomato plants, you can naturally boost their growth, improve flavour, repel pests, and maximize your harvest. Here are the top 10 companion plants that will help your tomatoes thrive.

1. Basil 

Why they work together: Basil and tomatoes are culinary soul mates, and they’re equally compatible in the garden. Basil repels aphids, spider mites, and hornworms while potentially enhancing tomato flavour. The aromatic oils in basil confuse pests that would otherwise target your tomatoes.

How to grow them together: Plant basil near tomato plants, either in between plants or around the perimeter of your tomato bed. Both prefer full sun and well-draining soil.

Pinch basil flowers regularly to keep the plant producing leaves and to prevent it from going to seed. As your tomatoes grow tall, the basil will provide ground cover and help retain soil moisture.

2. Lettuce

Why they work together: Lettuce grows quickly and stays low to the ground, making it an excellent living mulch around tomato plants.

It helps retain soil moisture, suppress weeds, and cool the soil during hot weather. Lettuce also doesn’t compete with tomatoes for nutrients or space.

How to grow them together: Plant lettuce near tomato plants, choosing varieties that mature quickly like loose-leaf types. As tomatoes grow taller, they’ll provide beneficial afternoon shade for lettuce during summer heat.

Succession plant lettuce every 2-3 weeks for continuous harvest, and replace with heat-tolerant varieties as temperatures rise.

3. Borage

Why they work together: Borage is renowned for improving tomato flavour and growth while repelling hornworms and cabbage worms. Its beautiful blue flowers attract pollinators and beneficial insects.

Borage also accumulates potassium in its leaves, which benefits tomatoes when the plant decomposes.

How to grow them together: Plant borage near tomatoes, keep in mind that they can grow quite large. It prefers full sun and well-draining soil.

Borage readily self-seeds, so deadhead flowers if you don’t want volunteers next year. The plant’s deep taproot helps bring nutrients up from lower soil layers, benefiting nearby tomatoes.

4. Peppers

Why they work together: As members of the nightshade family, peppers and tomatoes have similar growing requirements and don’t compete for different nutrients.

Peppers can help confuse pests that specifically target tomatoes, while both plants benefit from similar soil conditions and care routines.

How to grow them together: Space pepper plants near tomatoes, but make sure to allow proper air circulation. Both need warm soil, full sun, and consistent watering.

Plant them at the same time after the last frost, and use the same fertilization schedule. Taller tomato plants can provide some afternoon shade for heat-sensitive pepper varieties.

5. Carrots

Why they work together: Carrots grow deep underground while tomatoes have shallow feeder roots, making them perfect spatial companions.

Carrots help break up compacted soil, improving drainage and root penetration for tomatoes. They also don’t compete for nutrients since they occupy different soil layers.

How to grow them together: Sow carrot seeds directly in the soil around established tomato plants, about 4-6 inches away from the base.

Choose shorter carrot varieties like Paris Market or Thumbelina if space is limited. The carrots will be ready to harvest before tomatoes reach peak production, making efficient use of garden space.

6. Nasturtiums

Why they work together: Nasturtiums act as trap crops, attracting aphids, whiteflies, and cucumber beetles away from tomatoes. They also repel hornworms and can improve tomato flavour.

As a bonus, nasturtium flowers and leaves are edible and add a peppery flavour to salads.

How to grow them together: Plant nasturtiums near tomato plants, either as a border around your tomato bed or interspersed throughout.

They prefer slightly poor soil and full sun to partial shade. Allow them to trail and spread, but monitor for pest buildup and remove heavily infested plants if necessary.

7. Chives

Why they work together: Chives repel aphids, Japanese beetles, and carrot flies while attracting beneficial insects like bees and predatory wasps.

Their sulphur compounds help deter many common tomato pests, and they’re said to improve tomato flavor and growth.

How to grow them together: Plant chives near tomato plants in small clumps. They prefer well-draining soil and full sun to partial shade.

Chives are perennial and will return year after year, making them excellent permanent companions. Allow some flowers to bloom to attract beneficial insects, then cut them back for continuous leaf production.

8. Parsley

Why they work together: Parsley attracts beneficial insects like hover-flies and parasitic wasps that prey on tomato pests. It also serves as a host plant for beneficial insects and doesn’t compete with tomatoes for resources. Some gardeners report improved tomato flavour when grown with parsley.

How to grow them together: Plant parsley near tomato plants in partial shade to full sun. Both flat-leaf and curly varieties work well.

Parsley prefers consistently moist soil and cooler temperatures, so it benefits from the shade cast by mature tomato plants. Allow some plants to flower in their second year to maximize beneficial insect attraction.

9. Marigolds

Why they work together: Marigolds are powerhouse pest deterrents that release compounds toxic to nematodes, whiteflies, and aphids.

French marigolds are particularly effective at reducing root-knot nematodes in the soil, which can damage tomato roots.

How to grow them together: Plant marigolds near tomato plants throughout your garden bed. They prefer full sun and well-draining soil, similar to tomatoes.

Choose compact varieties that won’t compete for space. Deadhead spent flowers to encourage continuous blooming and pest protection throughout the growing season.

10. Oregano

Why they work together: Oregano provides strong pest deterrent properties, repelling aphids, spider mites, and cabbage moths. Its intense aroma can mask the scent of tomatoes from potential pests.

Oregano also attracts beneficial insects and can improve the overall health of your garden ecosystem.

How to grow them together: Plant oregano near tomato plants, allowing room for it to spread. Choose compact varieties like Greek oregano for smaller spaces.

Oregano prefers full sun and well-draining soil, similar to tomatoes. Harvest regularly to keep plants bushy and productive, and allow some flowers to bloom for beneficial insects.

Planting tips for success

Timing: Plant annual companions like basil, marigolds, and nasturtiums after the last frost when you transplant tomatoes. Perennial herbs like chives and oregano can be planted earlier in the season.

Spacing: Always consider mature plant sizes when planning your companion planting layout. Overcrowding reduces air circulation and can lead to disease problems.

Soil preparation: Most of these companions prefer similar soil conditions to tomatoes: well-draining, fertile soil with a pH between 6.0-7.0.

Water management: Group plants with similar water needs together, and consider how companion plants might affect soil moisture and drainage.

Succession planting: For continuous harvest and pest control, succession plant quick-growing companions like lettuce and replant annual flowers throughout the season.

By incorporating these companion plants into your tomato garden, you’ll create a thriving ecosystem that naturally supports healthy growth, reduces pest problems, and maximizes your harvest. Remember that successful companion planting takes observation and adjustment—pay attention to how your plants interact and modify your approach based on your garden’s unique conditions.