Cabbage companion plants
Cabbage (*Brassica oleracea* var. *capitata*) spends 70–120 days in the garden from transplant to harvest, and for most of that time it is a target for specialist brassica pests. The pest complex includes imported cabbageworm (*Pieris rapae*), cabbage looper (*Trichoplusia ni*), diamondback moth.
—- title: "Cabbage companion plants" slug: cabbage-companion-plants hub: care category: "Companion planting" description: "Companion planting for cabbage to reduce imported cabbageworm, harlequin bug, and aphid damage — with evidence-based recommendations and a complete foe list." date: 2026-06-10 updated: 2026-06-10 author: "Thomas A." reading_time: 9 release_after: 2026-07-21 —-
Cabbage (Brassica oleracea var. capitata) spends 70–120 days in the garden from transplant to harvest, and for most of that time it is a target for specialist brassica pests. The pest complex includes imported cabbageworm (Pieris rapae), cabbage looper (Trichoplusia ni), diamondback moth (Plutella xylostella), cabbage aphid (Brevicoryne brassicae), and in warm regions, harlequin bug (Murgantia histrionica).
Companion planting for cabbage addresses this pest complex by disrupting the volatile signals pests use to locate host plants, and by supporting the parasitic insects that attack caterpillars and aphids.
The companion planting table
| Plant | Role | Friend / Foe / Neutral | Notes |
|---|---|---|---|
| Dill (Anethum graveolens) | Attracts Cotesia glomerata (cabbageworm parasitoid) | Friend | Allow to flower near bed edges |
| Cilantro (Coriandrum sativum) | Aphidius wasp attractor for aphid control | Friend | Succession-sow every 3 weeks |
| Sweet alyssum (Lobularia maritima) | Syrphid flies predate aphids; living mulch | Friend | Row edges and paths |
| Nasturtium (Tropaeolum majus) | Aphid trap crop | Friend | Upwind of cabbage; monitor weekly |
| Thyme (Thymus spp.) | Aromatic volatile confusion for cabbage moths | Friend | Row border planting |
| Sage (Salvia officinalis) | Same aromatic mechanism as thyme | Friend | Traditional kitchen garden companion |
| Rosemary | Aromatic; traditional companion | Friend (weak) | Limited experimental evidence |
| Chamomile | Calcium accumulation; anecdotal growth benefit | Neutral | Traditional; not experimentally confirmed |
| Celery | Traditional deterrent for cabbage moths | Friend (weak) | Based on tradition; limited controlled evidence |
| Marigold, French (Tagetes patula) | Beneficial insect support; nematode management | Friend | Bed perimeter |
| Beets | Compatible cool-season companion; efficient space use | Neutral | No pest interaction documented |
| Onion | Mixed — allium volatiles may help, but minimal evidence | Neutral | Lower risk than full garlic but not strongly supported |
| Other brassicas (kale, broccoli, cauliflower) | Amplifies pest attractant signals | Foe | Do not block-plant brassicas together |
| Fennel (Foeniculum vulgare) | Strongly allelopathic | Foe | Separate beds entirely |
| Strawberries | Cabbage and strawberries are documented mutual inhibitors | Foe | Some evidence of allelopathy in both directions |
| Tomatoes | Different pest complex; no documented interaction | Neutral | Compatible; no documented benefit or harm |
How parasitic wasps protect cabbage
Per Cornell Cooperative Extension, Cotesia glomerata is a parasitic wasp that lays its eggs inside imported cabbageworm caterpillars. The larvae develop inside the caterpillar, eventually killing it. This wasp is a highly effective natural control when present in sufficient numbers.
The adults require flower nectar as food. Per UC IPM, umbellifers — dill, cilantro, parsley, bishop's weed — are among the most attractive nectar sources for these wasps. Establishing these plants before cabbageworm pressure begins (in spring, before Pieris rapae adults start flying) allows wasp populations to build proactively.
Row cover as primary protection
Per Penn State Extension, floating row cover placed over transplants and secured at the edges provides near-complete exclusion of cabbage moth adults, preventing egg-laying. This is more reliable than companion planting for caterpillar management. Row cover must be removed for inspection, but can otherwise remain in place for the entire crop duration in most situations.
Companion planting and row cover are complementary: row cover for transplants through heading stage; companion plants throughout to build the beneficial insect community for when row cover is removed.
Strawberries and cabbage: a documented incompatibility
Per NC State Extension, there is some research supporting the idea that strawberries and cabbage inhibit each other's growth when planted in adjacent rows. The mechanism may involve exudate competition or allelopathy. This is one of the more specific foe relationships in vegetable companion planting research. Keep strawberry beds and brassica beds in separate areas of the garden.
Harlequin bug in warm climates
Per Texas A&M AgriLife Extension, harlequin bug (Murgantia histrionica) is a serious pest of brassicas in the southern US (roughly zones 7b and warmer). No companion plant reliably deters harlequin bug. The insects overwinter in old brassica plant debris and mustard weeds. The most effective management strategy is removing all brassica plant material at the end of the season and controlling mustard in and around the garden.
Succession and timing
Per Clemson HGIC, cabbage can be grown as a spring or fall crop in most zones. Spring crops (transplanted 4–6 weeks before last frost) are more susceptible to caterpillar damage because the main butterfly flights coincide with the growing period. Fall crops (transplanted in late July–August for zones 6–7) experience lower caterpillar pressure as temperatures drop, but aphid populations can be high in fall. Tailor companions accordingly: focus on caterpillar parasitoids for spring, aphid predators for fall.
Frequently asked questions
Does chamomile really improve cabbage growth? Chamomile is often cited in companion planting books as improving the flavor or growth of cabbage. Per Cornell Cooperative Extension, chamomile does accumulate calcium in its foliage and this calcium is released when chamomile decomposes, which may marginally benefit nearby plants. The direct growth improvement claim lacks controlled experimental support. Chamomile is a harmless addition and its flowers attract beneficial insects, but the specific growth claim should be treated as traditional wisdom rather than established fact.
Can I use Bt (Bacillus thuringiensis (BT spray)) alongside companion planting? Yes. Per UC IPM, Bt is a naturally occurring soil bacterium that kills caterpillars specifically and is safe for beneficial insects when applied as directed. Using Bt on caterpillar infestations does not harm the parasitic wasp populations supported by companion plants. Bt and companion planting are complementary strategies.
What is the best way to set up a 4-foot raised bed for cabbage with companions? Per Penn State Extension, a practical layout for a 4-foot raised bed: cabbage transplants at 18-inch spacing in the center; sweet alyssum seeded along both long edges; dill or cilantro at the north end corners; thyme as a front border facing south. Row cover the entire bed until heads begin to form.
How many dill plants do I need to provide meaningful parasitoid support? Per Cornell Cooperative Extension, at minimum 2–3 flowering dill plants per 10 feet of cabbage row provides measurable benefit in field conditions. More is better; succession-sowing dill every 4 weeks ensures continuous bloom across the season.
Sources
- Cornell Cooperative Extension — Brassica Pest Management and Companion Planting
- UC IPM — Cabbage and Cole Crop Pests
- Penn State Extension — Cabbage Production
- NC State Extension — Brassica Companion Planting
- Texas A&M AgriLife Extension — Harlequin Bug Management
- Clemson HGIC — Cabbage Production