What to Plant With Cabbage, Broccoli and Brussels Sprouts (and What the Research Says)
Quick answer
The evidence is weak. In one Florida trial published in 1997, collard rows had more diamondback moth caterpillars than the cabbage, but cabbage heads at harvest were no less damaged. Basil next to Brussels sprouts had an apparent effect on some pests in one study. Keep scouting for caterpillars either way.
Updated
The research on companions for the cabbage family is thin. In one Florida trial (published 1997), collard rows held more diamondback moth caterpillars than the cabbage, but cabbage heads at harvest were no less damaged. Basil next to Brussels sprouts had an “apparent” effect on some pests in one study.
Cabbage family companions: the evidence
| Claim | What the research says | Evidence |
|---|---|---|
| Collard rows as a trap crop for diamondback moth | In a Florida trial (spring 1995, published 1997), two rows of collards were planted between two cabbage fields. “More larvae of the diamondback moth (DBM)... were found on collard plants than on cabbage plants,” and parasitism of the larvae on collards “reached 72% in early May.” But “At harvest, there was no significant difference in damage ratings of cabbage heads sampled near the middle of the field and damage to heads on rows nearest the collards.” The authors concluded collard “may have potential as a trap crop” (Mitchell, Hu and Okine, Florida Entomologist 80(1), 1997). | Weak |
| Basil with Brussels sprouts against caterpillars | Bomford reported “An apparent inhibitory effect of companion planting on some pests of Brussels sprout (e.g. imported cabbageworm...)” in one study (Bomford, West Virginia University dissertation, 2004). | Weak |
| Perimeter trap crop for flea beetles | UMass: “Trap cropping can take advantage of the flea beetles' preference for particular brassicas by using the preferred species or varieties as a draw.” “Direct-seeded crops can be used around transplants if seeded 7-14 days earlier.” The beetles in the trap crop “can be killed there with an insecticide application”, so the trap is managed, not passive (UMass Extension, Brassica Flea Beetles). Kentucky: “Multiple studies have found that planting trap crops around a brassica cash crop can be an effective tool for flea beetle management.” Its strategies include “planting trap crops 1-2 weeks prior to the cash crop, dedicating 10% of the total planting area to trap crops, planting trap crops in a border around the perimeter of the cash crop”, and “Varieties with high levels of mustard oils, such as daikon radish and mustard, have been used successfully as trap crops around brassica plantings.” (University of Kentucky Entomology EF330) | Moderate(extension guidance, treated trap) |
| Turnip rape border around cauliflower | In caged field experiments, “Neither turnip rape plants nor cauliflower as a border significantly reduced flea beetle damage to main crop cauliflower plants, although the numbers of feeding holes in these plants were lowest where a turnip rape border was used.” Separation helped: “leaving gaps of 3–6 m of bare soil between turnip rape and cauliflower plants significantly reduced feeding damage to the latter, as compared to when plants were adjacent.” (“Living on the Edge: Using and Improving Trap Crops for Flea Beetle Management in Small-Scale Cropping Systems”, George, Port and Collier 2019, Insects 10(9):286) | Weak |
| Herbs (dill, mint, rosemary, sage, thyme, nasturtium) against cabbage pests | No qualifying extension or peer-reviewed test found. That is a gap in the research we reviewed, not proof the pairings fail. | None |
Evidence labels: Strong = several field trials or a clear extension recommendation built on trial data. Moderate = one or two trials, or extension guidance with limits. Weak = suggestive only. None = no qualifying test found.
What this means in a home garden
A collard row is cheap to try, but the one trial we found did not show cleaner cabbage at harvest, so keep checking plants for caterpillars as usual. For flea beetles, a trap border of a preferred brassica works best when it is managed and sown 7 to 14 days ahead (UMass); a border right next to the crop did not significantly protect it in the turnip rape study. Charts that pair cabbage with specific herbs are mostly untested: WSU says traditional charts have “entertainment, not scientific, value” (WSU Extension, The Myth of Companion Plantings).
See the companion planting hub, tomatoes and cucumbers and squash.
Sources
- American Geophysical Union (peer-reviewed journals): Bomford, West Virginia University dissertation, 2004
- UMass Extension: Brassica Flea Beetles
- University of Kentucky Extension: University of Kentucky Entomology EF330
- Washington State University Extension: WSU Extension, The Myth of Companion Plantings
Organic options Growing without synthetic sprays? See our organic gardening guides: pest control and fertilizer.