Plant marigolds, nasturtiums, and borage near tomatoes to attract helpful insects and confuse pests

The best flowers to plant alongside tomatoes are ones that either draw beneficial insects to your garden or act as a trap for pests that would otherwise attack your tomato plants. Marigolds are the most reliable choice—they repel aphids, whiteflies, and spider mites while their bright blooms attract pollinators. Nasturtiums work as a sacrificial crop: pests prefer them to tomatoes, so they draw damage away from your fruit. Borage brings in bees and parasitic wasps, which hunt the insects that feed on tomato leaves and fruit.

These flowers work because they change what your garden looks and smells like to insects. A tomato plant standing alone is straightforward for pests to find. Surrounded by other plants, especially ones with strong scents, it becomes harder to locate. At the same time, the right flowers attract the predators and parasites that keep pest populations in check naturally.

Key Takeaways

  • Marigolds repel common tomato pests like aphids and whiteflies while attracting pollinators that help fruit set.
  • Nasturtiums draw pests away from tomatoes by being a more attractive food source, reducing damage to your harvest.
  • Borage flowers bring in bees for pollination and parasitic wasps that hunt tomato pests.
  • Plant flowers at the base of tomato cages or in rows between plants, spacing them 12 to 18 inches apart depending on the variety.
  • Calendula and alyssum also work well and are easier to grow from seed than some other companion flowers.

Marigolds: The most reliable pest barrier

Marigolds are the standard choice for tomato gardens because they work in most climates and soil types. They produce a scent that repels spider mites, whiteflies, and aphids—three of the most common tomato pests. Plant them in clusters of three or four around the base of each tomato cage, or space them 12 inches apart in rows between tomato plants.

Marigolds bloom continuously from early summer through frost if you deadhead spent flowers (pinch off the dried blooms). This keeps them producing the compounds that repel pests all season long. They also tolerate poor soil and irregular watering, so they won't compete with your tomatoes for resources. Choose varieties like 'Neon' or 'Bonanza' if you want larger flowers, or 'Signet' types if you prefer delicate blooms that won't shade the tomato foliage.

Nasturtiums: A trap crop that protects tomatoes

Nasturtiums work differently than marigolds. Instead of repelling pests, they attract them—but they attract pests to themselves rather than to your tomatoes. Aphids and whiteflies prefer nasturtium leaves to tomato leaves, so they congregate on the flowers instead. This is called a trap crop or sacrificial planting. Your nasturtiums take the damage, and your tomatoes stay clean.

Plant nasturtiums on the outer edge of your tomato bed, where they will be the first plants pests encounter. Space them 18 inches apart because they grow larger and bushier than marigolds. Nasturtiums also produce edible flowers with a peppery taste, so you gain a bonus harvest. They prefer cooler weather and can struggle in very hot climates, so in hot regions plant them in spring or fall rather than mid-summer.

Borage: Bringing in beneficial insects

Borage is a tall, airy flower with blue or pink blooms that bees visit constantly. More importantly, borage attracts parasitic wasps—tiny insects that lay eggs inside tomato hornworms and other caterpillars. When the wasp eggs hatch, the larvae consume the pest from the inside, killing it before it can damage your fruit. Borage also draws in hoverflies, whose larvae feed on aphids.

Borage grows quickly from seed and can reach 2 to 3 feet tall, so plant it on the north side of your tomato bed where it won't shade the plants. Space plants 18 to 24 inches apart. The flowers are edible and taste like cucumber, so you can add them to salads. Borage self-seeds readily, so if you let a few flowers go to seed at the end of the season, you will have volunteer plants the following year.

Calendula and alyssum for smaller gardens

If space is tight, calendula (pot marigold) and sweet alyssum are compact alternatives. Calendula grows 12 to 18 inches tall and produces the same pest-repelling scent as regular marigolds. It also attracts hoverflies and parasitic wasps. Sweet alyssum is even smaller—6 to 12 inches—and creates a low border around tomato plants. Its tiny flowers attract beneficial insects and smell sweet without overwhelming the garden.

Both are straightforward to grow from seed and bloom quickly. Alyssum is especially useful in containers or raised beds where you want to maximize tomato space. Calendula tolerates cooler weather better than marigolds, so it is a good choice in northern regions or for spring and fall planting.

How to plant flowers with tomatoes

Plant flowers at the same time you plant tomatoes, or wait until tomatoes are 6 to 8 inches tall and established. Space flowers 12 to 18 inches from the tomato stem, depending on the variety—marigolds and alyssum closer, nasturtiums and borage farther out. This gives tomato roots room to spread without competition.

Water flowers and tomatoes together, but do not overwater. Most companion flowers prefer soil that dries slightly between waterings. Fertilize sparingly—too much nitrogen encourages leafy growth at the expense of flowers and fruit. If you are using a balanced fertilizer for tomatoes, it will feed the flowers adequately. Deadhead spent blooms on marigolds and calendula to keep them flowering all season.

Flowers to avoid near tomatoes

Fennel and dill are sometimes recommended as companion plants, but they actually inhibit tomato growth by releasing compounds that slow root development. Avoid planting them in the same bed. Brassicas like cabbage and broccoli compete with tomatoes for nutrients and attract different pests, so they are better suited to separate garden areas.

Avoid planting flowers that require heavy fertilization or frequent watering, as they will compete with tomatoes for both. Roses, for example, need regular feeding and can attract spider mites that also attack tomatoes. Stick to hardy, low-maintenance flowers that thrive in the same conditions as your tomatoes.

Frequently Asked Questions

Can I plant flowers in containers with tomatoes?

Yes, but only in large containers—at least 5 gallons for a tomato plant plus flowers. Use a pot at least 18 inches wide and deep. Plant the tomato in the center and add one or two small flowers like alyssum or calendula around the edge. Water more frequently in containers because soil dries faster.

Do I have to deadhead marigolds?

Deadheading keeps marigolds flowering longer and maintains their pest-repelling potency, but it is not required. If you do not deadhead, they will still bloom and help your tomatoes, just less prolifically. Deadheading takes a few minutes every week or two.

What if pests still damage my tomatoes even with companion flowers?

Companion flowers reduce pest pressure but do not eliminate it entirely, especially in severe infestations. If damage is heavy, inspect the undersides of leaves for eggs or insects, remove affected leaves by hand, or use neem oil or insecticidal soap according to label directions. Companion flowers work best as part of a broader pest management approach.

Can I plant the same flowers every year?

Yes. Rotating flower varieties is not necessary for companion planting. If marigolds worked well one year, plant them again. However, rotating your tomato location every two to three years helps prevent soil-borne diseases from building up, regardless of what flowers you plant nearby.

When should I plant flowers if I start tomatoes indoors?

Start flower seeds indoors at the same time as tomatoes, or direct-seed them outdoors after the last frost date. If you transplant tomatoes into the garden before flowers are ready, plant flowers when tomatoes are 6 to 8 inches tall. This gives both time to establish before peak pest season in mid-summer.