Your cabbage heads have green caterpillars chewing holes in them and aphids colonising the brassica leaves. You could spray. You could pick caterpillars off by hand for the next six weeks. Or you could plant a $2 packet of dill seed and let nature deploy parasitic wasps for you.
Dill (Anethum graveolens) is one of the highest-leverage companion plants in a US backyard garden. Its umbel flowers attract over a dozen species of beneficial predators that hunt the most common vegetable pests. Its leaves host black swallowtail butterfly caterpillars. Its strong scent confuses aphids and spider mites. And yet it has three specific neighbours it absolutely should not grow next to. This guide covers what to plant with dill, what to keep away from it, and exactly how to lay out a dill-anchored bed.
Key Takeaway
The best companions for dill are brassicas (cabbage, broccoli, kale, Brussels sprouts), cucumbers, asparagus, lettuce, onions, and beans. Keep dill far away from carrots (cross-attracts pests, suppresses growth when flowering), fennel (cross-pollination plus allelopathy), and cilantro (similar Apiaceae conflict). The dill-tomato relationship is more nuanced: young dill helps tomatoes, but flowering dill competes for nutrients. Succession-plant every 2 to 3 weeks for continuous harvest.
Dill belongs to the Apiaceae family, the same plant family as carrots, parsley, and fennel. The defining feature of this family is the umbel flower: a flat, plate-like cluster of dozens of tiny individual flowers, each producing easily accessible nectar.
Cornell Botanic Gardens' beneficial insect guide documents that this flower structure is what attracts predatory insects with short mouthparts that cannot reach into deeper bell-shaped flowers. The same applies to dill, fennel, and parsley umbels.
The beneficials dill attracts and what they hunt:
The UF/IFAS Extension insectary plant guide lists dill alongside parsley, fennel, and cilantro as the most reliable cool-season insectary plants for attracting these predators to vegetable gardens.
Companion lists cross-referenced from Homesteading RD's dill guide and Gardener's Path.
| Companion | What dill does for it | Placement |
| Cabbage, broccoli, kale, Brussels sprouts | Wasps parasitise cabbage moth eggs and caterpillars | Plant dill at row ends and corners of brassica bed |
| Cucumber | Repels cucumber beetle, attracts pollinators | Scatter through cucumber bed |
| Asparagus | Attracts predators of asparagus beetle | Interplant between asparagus crowns |
| Lettuce | Light shade in summer; aphid control | South side of lettuce bed |
| Onions, leeks, garlic | Mutual aromatic confusion of pests | Interplanted rows |
| Corn | Trichogramma wasps attack corn earworm eggs | Border rows around corn block |
| Beans (bush varieties) | Mutual pollinator attraction; no allelopathy | Adjacent rows |
Source: Cornell University cooperative extension companion planting guide via K-State Midway District distribution.
Critical: Never Plant Dill With Carrots
Dill and carrots are both in the Apiaceae family. They share the same pests (carrot fly, leaf miners) so a mixed bed concentrates infestation. Worse, flowering dill is allelopathic to carrots and will stunt their growth significantly. Gardenia's carrot companion guide confirms dill should be kept at the opposite end of the garden from any carrot row.
The full list to keep away from dill:
Almost every companion planting list contradicts itself on dill and tomato. The research-based answer is conditional. Young, vegetative dill helps tomatoes by attracting predators of tomato hornworm and aphids. Mature, flowering dill competes with tomatoes for nutrients and water, and large dill umbels can shade tomato lower leaves.
The practical solution: plant dill 3 ft (0.9 m) away from tomatoes, let it flower for hornworm control, and pull it before it goes to seed. Alternatively, harvest dill leaves continuously and never let it flower until you remove it at the end of the season.
Why This Works (the permaculture lens)
Companion planting is not a static lookup table. It is a sequence of plant relationships that change as each plant moves through its life stages. Young dill provides nectar to pollinators and habitat for predator nymphs. Flowering dill becomes a beneficial insect refueling station. Bolted dill provides seed for both kitchen and next year's volunteers. The mistake is treating "dill" as one thing instead of four overlapping functions you can deploy at different times. This is the same principle as the observe and interact permaculture principle in action: pay attention to which life stage of the plant is doing what work.
The black swallowtail butterfly (Papilio polyxenes) lays its eggs on dill, parsley, fennel, and carrot tops. Each female lays 200 to 400 eggs, and the green-and-black-striped caterpillars defoliate plants enthusiastically. Most gardeners panic and squash them. The permaculture approach is to plant extra dill specifically as a sacrificial host crop.
Practical setup: grow 6 to 10 dill plants for kitchen use, plus 2 to 3 extra plants in a corner labeled "swallowtail kindergarten." When caterpillars appear, move them to the sacrificial plants by hand. They reach adulthood in 3 to 4 weeks, pupate, and emerge as one of the most beautiful pollinators in the US. The swallowtail butterflies then return to the garden to pollinate.
Dill is direct-seeded after the last frost. Transplants rarely succeed because the taproot does not like disturbance.
Sow when soil hits 60 to 70 F (16 to 21 C)
Soil temperature matters more than calendar date. Direct sow 1/4 in (6 mm) deep, lightly covered. Light aids germination, so do not bury seeds deeply.
Space 8 to 12 in apart
Final spacing of 8 to 12 in (20 to 30 cm). Sow thicker and thin after germination (you can use thinnings in salads or pickles).
Succession-sow every 2 to 3 weeks
Dill bolts (flowers and goes to seed) once temperatures hit 80 F (27 C) consistently. Succession sowing ensures continuous leaf harvest from May through October.
Provide light support for tall varieties
Mammoth dill reaches 5 ft (1.5 m) and can flop. Bronze dill and fernleaf dill stay shorter (18 to 24 in / 45 to 60 cm) and need no support.
Let some plants self-seed
One mature plant produces 1,000+ seeds. Let one or two go to seed each year and you will have volunteer dill seedlings for the next 3 to 5 years without resowing.
| Cultivar | Height | Best use |
| Mammoth (Long Island Mammoth) | 3 to 5 ft (0.9 to 1.5 m) | Seed production for pickling |
| Fernleaf | 18 to 24 in (45 to 60 cm) | Container growing, slow to bolt |
| Bouquet | 30 to 36 in (75 to 90 cm) | All-purpose, large umbel flowers |
| Dukat | 24 to 36 in (60 to 90 cm) | Leaf production; slow-bolt |
| Bronze | 18 to 24 in (45 to 60 cm) | Ornamental and culinary use |
Dill grows well in containers if you pick the right cultivar. Fernleaf and bouquet dill stay short enough for a 10 in (25 cm) pot. Mammoth needs at least a 15 gallon (57 L) container for the taproot.
Best container pairings: dill with lettuce, dill with bush beans, dill with chives. Avoid containers that combine dill with cilantro, carrots, or parsley because they compete for the same nutrients and root space.
For broader companion context see our complete companion planting chart, our herb companion planting guide, and our overview of permaculture principles in the garden.
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Read the Free GuideWhat should not be planted near dill?
Carrots, fennel, cilantro, caraway, anise, and lavender. Carrots and dill share pests and dill stunts carrot growth when flowering. Fennel and cilantro cross-pollinate with dill, ruining seed quality. Lavender prefers much drier conditions than dill.
Can you plant dill with tomatoes?
Yes, with timing. Young dill helps tomatoes by attracting tomato hornworm predators. Mature flowering dill competes with tomatoes for nutrients. Plant dill 3 ft (0.9 m) from tomato plants and pull it before it goes to seed, or harvest leaves continuously to prevent flowering.
What grows best with dill?
Brassicas (cabbage, broccoli, kale, Brussels sprouts), cucumbers, asparagus, lettuce, onions, beans, and corn. Dill attracts predatory wasps that protect brassicas from cabbage worm and corn from earworm. Cucumbers benefit from dill's pollinator draw.
Can you plant dill and basil together?
Yes, basil and dill are compatible. They have similar water and sun needs and do not compete for nutrients. Both attract beneficial insects, making them strong herb-bed neighbors.
Can you plant dill with cucumbers?
Yes, this is one of the strongest dill pairings. Dill repels cucumber beetles, attracts pollinators that improve cucumber yield, and the harvest timing aligns perfectly (pickling cucumbers ready at the same time as dill seed heads).
Why does dill attract beneficial insects?
Dill's umbel flowers are flat clusters of hundreds of tiny individual flowers, each producing easily accessible nectar. Beneficial predators like hoverflies, parasitic wasps, and ladybugs have short mouthparts and cannot reach into deeper flowers. Umbel flowers feed them efficiently.
Will dill come back every year?
Dill is an annual but self-seeds prolifically. One plant produces 1,000+ seeds. Let one or two go to seed each year and you will have volunteer seedlings for the next 3 to 5 years without resowing.
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