Yes, dill is a good companion plant for tomatoes

Dill grows well next to tomatoes and offers real benefits to your garden. It attracts beneficial insects — particularly parasitic wasps and hoverflies — that prey on common tomato pests like aphids and hornworms. Dill also has a shallow root system that does not compete with tomato roots for water and nutrients deep in the soil, so the two plants can share the same bed without one starving the other.

The main trade-off is that dill is an annual herb that bolts (flowers and goes to seed) quickly in heat, especially in midsummer. Once it flowers, the leaves become less useful for cooking, though the flowers themselves attract even more beneficial insects. If you want dill for harvest, you will need to replant it every few weeks or grow it in a cooler part of your garden.

Key Takeaways

  • Dill attracts parasitic wasps and hoverflies that eat aphids, spider mites, and hornworms — three of the most common tomato pests.
  • Dill's shallow roots do not compete with tomato roots, so both plants can grow in the same bed without either one suffering nutrient loss.
  • Dill bolts quickly in hot weather, so succession planting every three to four weeks keeps a steady supply of usable leaves.
  • Plant dill at the edge of the tomato bed or between plants, not directly against the stem, to avoid shading the tomato foliage.

How dill protects tomatoes from pests

Dill flowers attract parasitic wasps, which lay their eggs inside aphids and spider mites. When the wasp larvae hatch, they consume the pest from the inside, killing it. Hoverflies (also called flower flies) are another predator that dill brings to your garden; their larvae eat 10 to 15 aphids per day. Both insects are drawn to the small, clustered flowers that dill produces, especially once it reaches the flowering stage.

Tomato hornworms — the large green caterpillars that can strip a plant bare in days — are also preyed upon by parasitic wasps. While dill alone will not eliminate hornworms, a garden with dill and other flowering herbs creates an environment where natural predators are present and hunting. This reduces the number of pests you have to remove by hand or treat with other methods.

The benefit is strongest when dill is allowed to flower, even if you are not harvesting the leaves. If pest pressure is high, let some dill plants go to seed and flower while you harvest leaves from younger plants in a succession planting.

Root competition and soil sharing

Tomato roots extend 12 to 18 inches deep and spread outward to find water and nutrients. Dill roots stay in the top 6 to 8 inches of soil. Because they occupy different soil layers, they do not compete for the same resources. You can plant dill directly between tomato plants or around the base of the tomato bed without worrying that dill will steal nitrogen or water from your tomatoes.

This makes dill one of the few herbs that works well in a densely planted tomato garden. Basil, another common tomato companion, also has shallow roots, but dill is taller and more delicate, so it takes up less horizontal space. If your tomato bed is crowded, dill fits into the gaps without shading the tomato foliage or creating humidity problems that lead to fungal disease.

Spacing and placement in the garden

Plant dill at the edge of the tomato bed or between plants, leaving at least 6 inches from the tomato stem. Dill grows 2 to 3 feet tall and can shade lower tomato leaves if planted too close. Good air circulation around tomato foliage prevents fungal diseases like early blight and septoria leaf spot, so do not let dill crowd the plant.

If you are growing dill for harvest, plant it in rows or clusters where you can reach it easily without brushing against tomato plants. Dill self-seeds readily, so if you let one or two plants flower and drop seeds, you may have volunteer dill sprouting in your garden next year. This can be helpful or annoying depending on your preference — remove seedlings if they are in the way, or let them grow if you want free dill.

Managing dill bolting in summer heat

Dill bolts when temperatures stay above 75°F for several weeks, especially in direct sun. Once it flowers, the leaves become tougher and more bitter, though they are still edible. The flowers are also edible and taste like dill, so bolting is not a total loss — you can use the flowers in pickles, salads, or as a garnish.

To keep a steady supply of tender dill leaves, plant new seeds every three to four weeks from spring through early summer. Stop planting in midsummer when heat is at its peak; instead, let your existing dill plants flower and attract beneficial insects. Resume planting in late summer (six to eight weeks before your first frost) for a fall harvest of tender leaves.

In very hot climates, grow dill in partial shade or in a location that gets afternoon shade. This slows bolting and extends the harvest window. Morning sun is still important for strong growth and pest-attracting flowers.

Other herbs that pair well with dill and tomatoes

Basil is the most famous tomato companion and works alongside dill without conflict. Basil repels flies and mosquitoes and has the same shallow-root advantage as dill. Parsley also grows well with tomatoes and attracts beneficial insects, though it takes longer to germinate and establish.

Marigolds, nasturtiums, and borage are flowers that serve similar roles to dill — they attract beneficial insects and do not compete with tomato roots. If you want a diverse pest-control garden, combine dill with one or two of these other plants rather than relying on dill alone. The variety of flowers and scents makes your garden less attractive to pests overall.

Frequently Asked Questions

Can I plant dill right next to a tomato plant?

Plant dill at least 6 inches away from the tomato stem to avoid shading the lower leaves. Dill grows tall and can block air circulation if planted too close, which increases the risk of fungal disease. The space between plants is ideal — dill will not interfere with tomato growth from that distance.

Does dill attract bad insects to tomatoes?

Dill attracts beneficial insects that eat pests, not the pests themselves. Aphids and spider mites may visit dill, but the parasitic wasps and hoverflies that dill brings to your garden will hunt them down. This is actually a feature — pests on the dill are easier to spot and control than pests hidden deep in tomato foliage.

What should I do when dill starts to flower?

Let it flower if you want to maximize pest control — the flowers are what attract beneficial insects most strongly. If you want to keep harvesting tender leaves, pinch off the flower buds and plant new dill seeds elsewhere. You can also harvest the flowers themselves for cooking once they open fully.

Will dill reseed itself in my tomato garden?

Yes, dill self-seeds readily if you let flowers mature and drop seeds. You may see volunteer dill plants the following year. Remove them if they are in the way, or let them grow if you want free dill. Volunteer plants often appear in unexpected spots, so check before weeding.