Collards growing profile.

Collards Companion Plants

What may help, what can compete, and where the evidence is still uncertain.

Collards Brassica oleracea var. viridis

Cool-season vegetable in the cabbage family. View plant profile →

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Quick answer

Evidence supports or conditionally supports growing collards with Cabbage. 1 popular pairing has no verified relationship, which is not the same as safe or harmful.

Every status below has a direction, mechanism, context and source. "No verified relationship" means we looked and found nothing usable; the planner then evaluates spacing, light, water and timing normally. How we classify evidence →

Conditional benefit (1)

Positive only when the stated conditions match; otherwise informational.

CabbageBrassica oleracea var. capitataConditionalTrap crop · diamondback moth Collards may affect CabbageSpring–Fall · perimeter · A continuous border row of collards ar…Tier B Review: August 15, 2026

Why?

Claim. Collards planted around cabbage attracted diamondback moth egg-laying and reduced the need to spray the cabbage in Florida field trials, provided the collard trap rows were maintained and treated.

Mechanism. Diamondback moths prefer to lay eggs on collards; larvae concentrate there instead of on cabbage.

Studied in. Florida, USA; collard rows around cabbage plots. (field)

Conditions. Plant collards 1–2 weeks before cabbage so they are larger and more attractive. A continuous border row of collards around the cabbage block. Collards must be present and attractive throughout the cabbage crop.

Management. Check the collards weekly; Remove or treat larvae on the trap rows before they move to the cabbage.

Applies when. Only where diamondback moth is a known problem; a single collard plant will not protect a bed.

Limitations. An unmanaged trap crop becomes a nursery for the pest.

Evidence. Tier B: One or more relevant controlled field studies or an authoritative synthesis tied to the crop, effect and arrangement. (field trial).

Sources. Mitchell 2000; Sustainable Agriculture Research and Education (SARE) 2009; Shelton 2006

Reviewed August 15, 2026 by Garden Planner editorial team (pending independent horticultural review). Record collards--cabbage--trap_crop v1. Request a correction.

No verified relationship (1)

Zero score and an honest unknown state. Spacing, light, water and timing are evaluated normally.

No verified relationship: we did not find a source that establishes a benefit or harm for these pairs. This is not the same as "compatible".

OnionAllium cepaNo verified relationshipOther Collards and Onion affect each other (mutual)Spring–Fall · arrangement unspecifiedUnknown Review: August 15, 2026

Why?

Claim. We did not find a source that establishes a benefit or harm between collards and onion.

Mechanism. None documented.

Conditions. Planted together Both plants must be present at the same time.

Applies when. The planner evaluates spacing, light, water and timing normally.

Limitations. No relationship documented.

Evidence. Unknown: No source meeting the inclusion rules. (none).

Sources. University of Minnesota Extension 2023

Reviewed August 15, 2026 by Garden Planner editorial team (pending independent horticultural review). Record collards--onion--other v1. Request a correction.

Example layout for collards

Documented arrangement with Cabbage: perimeter. A continuous border row of collards around the cabbage block. Plant collards 1–2 weeks before cabbage so they are larger and more attractive.

Worked example based on the record, not a photograph of a trial.

**Side view of collards (60–90 cm) beside typical companions, showing canopy, support, shade and access.**

When these companions overlap

Bed occupancy in Portland, Oregon (estimates). A relationship only matters while both plants are present.

Collards

Cabbage20 wk overlap

Onion24 wk overlap

Overlap in weeks
Cabbage	20 weeks
Onion	24 weeks

Crop rotation guidance

Rotation is about what occupied the bed in previous seasons and is calculated separately from the live companion relationships above.

Rotate collards on a 3-year cycle with other cabbage family crops (Cabbage, Broccoli, Cauliflower, Kale, Brussels sprouts). Shared risks: clubroot, cabbage root fly, cabbage white caterpillars.

Crop rotation hub · Brassicaceae family page

Physical and resource fit

No significant light, water, pH or sprawl conflicts with the listed companions at recommended spacing.

Fit checks come from plant attributes and apply even when a pairing has a positive claim.

Community observations (anecdotal)

These reports come from gardeners and are not reviewed evidence. Results vary with soil, climate and practice. Community data never changes an evidence tier or a planner score.

Reports for collards: 0 (community submissions open in a later phase; drafts are stored only on your device).

**Community-submitted photo area (moderated) with context fields: region, season, layout, varieties, outcome.**

Record an observation

Evidence summary and sources

Management of diamondback moth (Lepidoptera: Plutellidae) in cabbage using collard as a trap crop — HortScience, 2000 (field)
Using trap crops to reduce pests — SARE / USDA, 2009 (guidance)
Concepts and applications of trap cropping in pest management — Annual Review of Entomology, 2006 (synthesis)
Companion planting in home gardens — University of Minnesota Extension, 2023 (guidance)

Reviewer: Garden Planner editorial team (pending independent horticultural review). Status counts on the Companions A–Z page are derived from these records. Corrections.