Kale growing profile.

Kale Companion Plants

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

Kale Brassica oleracea var. sabellica

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

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Quick answer

Evidence supports or conditionally supports growing kale with Sweet alyssum. 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.

Sweet alyssumLobularia maritimaConditionalSupports beneficial insects · cabbage aphid Sweet alyssum may affect KaleSpring–Fall · strip · Within a few metres.Tier C Review: August 15, 2026

Why?

Claim. By extension from broccoli and lettuce trials, alyssum near kale may support hoverflies that eat cabbage aphids; not tested on kale.

Mechanism. Insectary flowers feeding aphid predators.

Studied in. Related crop trials (broccoli, lettuce). (home garden)

Conditions. Planted together Within a few metres. Both plants must be present at the same time.

Management. Small share of the bed in alyssum.

Applies when. Plausible; indirect evidence.

Limitations. Indirect evidence only.

Evidence. Tier C: Indirect evidence: greenhouse or pot work, a related crop or species, or credible extension guidance with important uncertainty. (field trial).

Sources. Brennan 2016; Hogg 2011

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

Example layout for kale

Documented arrangement with Sweet alyssum: strip. Within a few metres. Planted together

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

**Side view of kale (45–90 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.

Kale

Sweet alyssum26 wk overlap

Onion24 wk overlap

Overlap in weeks
Sweet alyssum	26 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 kale on a 3-year cycle with other cabbage family crops (Cabbage, Broccoli, Cauliflower, Brussels sprouts, Collards). 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 kale: 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

Agronomy of strip intercropping broccoli with alyssum for biological control of aphids — Biological Control, 2016 (field)
Attractiveness of common insectary and harvestable floral resources to beneficial insects — Biological Control, 2011 (field)
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.