Kohlrabi Companion Plants
Brassica oleracea var. gongylodes · cabbage family family · rotation group: brassica
The best companion plants for kohlrabi are White Clover (undersown living mulch), Dill, Onion, Beet, and Lettuce. Avoid planting kohlrabi near Cabbage and other brassicas, Strawberry, Pole Bean, Tomato. Of the 13 pairings recorded here, 2 are supported by published research and 9 are traditional practice with no controlled evidence behind them.
What to plant with kohlrabi
| Plant | Claimed benefit | Evidence | What the evidence actually shows |
|---|---|---|---|
| White Clover (undersown living mulch) | A low clover living mulch between brassica plants reduces colonization by cabbage root fly and aphids. | Research-backed | Warwick Crop Centre field work behind the 'appropriate/inappropriate landings' model found that green ground cover between brassicas sharply increases wasted landings by host-seeking flies; the caveat is that clover competes for water and nitrogen and can cut yield if not managed. |
| Beet | Beets and kohlrabi share a cool season and root at different depths, so they interplant without competing. | Traditional | A sensible spacing and timing pairing repeated across garden literature; no controlled trial supports a measurable yield or pest benefit. |
| Dill | Flowering dill umbels feed parasitoid wasps and hoverflies that attack cabbageworms and aphids. | Traditional | Umbel flowers genuinely are nectar sources for small parasitoids, but I found no controlled garden-scale trial showing dill interplanting reduces pest damage on kohlrabi specifically. |
| Lettuce | Lettuce fills the gaps between kohlrabi plants and is harvested before the bulbs need the room. | Traditional | A legitimate space-use technique rather than a biological interaction; the only documented benefit is more harvest per square foot. |
| Nasturtium | Nasturtium acts as a trap crop pulling aphids off kohlrabi. | Traditional | Nasturtium does reliably attract cabbage aphids, but no trial I could find shows that this lowers aphid numbers on the adjacent brassica rather than simply raising them nearby. |
| Onion | Onions interplanted with kohlrabi deter cabbage pests with their odor. | Traditional | Onion was one of the plants tested in the Warwick root-fly work and gave no odor-specific advantage over any other green plant; it is a fine neighbor, just not a scent-based repellent. |
| Spinach | Spinach shares kohlrabi's cool-season window and shades soil between plants. | Traditional | Compatible culture is well documented; the shading benefit is plausible but unquantified, and no pest effect has been tested. |
| Marigold | Marigolds planted among kohlrabi repel cabbage root fly and cabbageworms by smell. | Not supported | Marigold was also in the Warwick aromatic-plant trials and performed no better than any other green plant; marigold's genuine, well-supported use is as a full-season cover crop against root-knot nematodes, which is a different practice entirely. |
| Thyme | The strong scent of thyme masks kohlrabi and repels cabbage moths and root flies. | Not supported | Thyme was one of the aromatic species directly tested by Finch, Billiald and Collier; aromatic plants were no more effective than non-aromatic ones, and green paper models with no scent at all worked equally well, so the scent-masking mechanism is tested and unsupported. |
What not to plant with kohlrabi
| Plant | Claimed problem | Evidence | What the evidence actually shows |
|---|---|---|---|
| Cabbage and other brassicas | Planting kohlrabi with or after other brassicas concentrates shared pests and soilborne disease. | Research-backed | This one is real: clubroot resting spores persist in soil for years and cabbage maggot, flea beetle and diamondback moth all move freely between brassica hosts, which is why extension guidance is a multi-year rotation away from the whole family. |
| Pole Bean | Pole beans and kohlrabi suppress each other's growth. | Traditional | No controlled evidence of chemical interference was found; the observable issue is that a bean trellis shades a low crop that wants full sun. |
| Strawberry | Brassicas near strawberries stunt the berries. | Traditional | A very widely repeated pairing with no controlled test behind it; the plausible part is simply competition for light and nitrogen between a heavy feeder and a shallow-rooted perennial. |
| Tomato | Tomatoes and kohlrabi compete heavily and should be separated. | Traditional | Untested as a biological antagonism; the real conflict is practical, since tomatoes shade the bed and occupy it through the heat when kohlrabi has already bolted. |
The honest verdict
Of everything gardeners recommend planting alongside kohlrabi, 1 pairing has been tested properly: White Clover (undersown living mulch). Those are the ones worth planning your bed around.
The remaining 6 pairings on this page are traditional practice. They circulate on every companion planting chart online, but we could not find controlled evidence testing them. They are not wrong so much as unverified — most cost nothing to try, and interplanting flowers and herbs has its own well-documented benefit of pulling pollinators and predatory insects into the garden.
Widely repeated, not supported: Thyme — Thyme was one of the aromatic species directly tested by Finch, Billiald and Collier; aromatic plants were no more effective than non-aromatic ones, and green paper models with no scent at all worked equally well, so the scent-masking mechanism is tested and unsupported.; Marigold — Marigold was also in the Warwick aromatic-plant trials and performed no better than any other green plant; marigold's genuine, well-supported use is as a full-season cover crop against root-knot nematodes, which is a different practice entirely.
Every row above links to the publication it came from. See how we grade evidence.
Growing kohlrabi: the numbers
| Sun | Full sun (6+ hours) |
|---|---|
| Water | Moderate |
| Spacing | 6 in apart · 18 in between rows · 4 per square foot |
| Mature size | about 12 in tall |
| Soil pH | 6–7.5 |
| Days to maturity | 50–60 days |
| Frost tolerance | Half-hardy — takes a light frost |
| Containers | Yes — 3 gallon minimum |
| Typical yield | 1 bulb, 2-3 in across |
| Common pests | flea beetle, imported cabbageworm, cabbage looper, diamondback moth, cabbage maggot, swede midge, aphid |
| Common diseases | clubroot, black rot, blackleg, alternaria leaf spot |
When to plant kohlrabi
Zone 6b shownStart seeds indoors: Feb 27 – Mar 13 — 4–6 weeks before your last frost
Direct sow outdoors: Mar 20 – Apr 2 — 3 weeks before last frost
Transplant outdoors: Mar 27 – Apr 9 — 2 weeks before last frost
Expected harvest: May 16 – May 26 — 50–60 days from planting
Fall planting: Aug 25 – Sep 7 — 9 weeks before your first fall frost
Those dates are for zone 6b. Get your own dates by ZIP code →
Varieties worth knowing
seeds- Early Purple Vienna — early reddish-purple standard listed by Iowa State Extension
- Kolibri — deep purple hybrid, uniform bulbs, Iowa State Extension recommendation
- Quickstar — pale green, fast for spring sowing
- Winner — pale green hybrid, holds tender longer before turning woody
Variety names link to seeds on Amazon. As an Amazon Associate we earn from qualifying purchases. These are the varieties named in the extension sources for this crop, not a paid placement — where a source recommended a variety for a specific reason, that reason is the note beside it.
Put it in a bed
The garden planner checks every square against this ledger as you place crops — if you drop kohlrabi next to something recorded as a bad neighbour, the square turns red and tells you why.
Records for the plants named above:
Same rotation group (brassica) — don't follow one with another:
Kohlrabi companion planting questions
What should not be planted next to kohlrabi?
How far apart should kohlrabi be planted?
Does companion planting with kohlrabi actually work?
When should I plant kohlrabi?
Sources for this record
- Growing kohlrabi in home gardens — University of Minnesota Extension
- Growing Kohlrabi in the Home Garden — Iowa State University Extension Yard and Garden
- Kohlrabi — Illinois Extension Home Vegetable Gardening
- Seed Planting Guide — Penn State Extension Master Gardeners of York County
Record compiled 2026-07. Spot an error or a study we missed? Tell us and we'll correct the entry.