Kohlrabi

Brassica oleracea (Gongylodes Group)

About it

Kind: Vegetables · Annual
Family: Brassicaceae
Frost: Hardy — takes a hard frost
Sun: Full sun
Spacing: 4 in apart
Soil depth in a pot: At least 8 in
Water: About every 7 days

ⓘ We don't know this plant's soil pH, feeding needs and mature size yet.

When to plant

Start indoors: 6 weeks before planting out
Plant out: Plant out 4 weeks before the last frost
Sow outdoors: Sow 4 weeks before the last frost
Soil temperature: Germinates from 40°F
Ready: About 50 days from sowing

Based on your last frost date. Outside the US, check local advice.

Planting partners

What has been claimed about growing Kohlrabi near other plants, grouped by how well it has been tested. Most companion planting advice has never been tested; the notes say which is which.

Tested in field trials

With Chinese Cabbage Napa cabbage grown as a trap crop beside other brassicas draws flea beetles away from them; in trials only a mix of three trap-crop species improved the protected broccoli's yield. UMN Extension ↗Europe PMC ↗
With Mustard Greens Mustard grown as a trap crop beside other brassicas draws flea beetles away from them; in trials only a mix of three trap-crop species improved the protected broccoli's yield. UMN Extension ↗Europe PMC ↗

Mixed evidence

With Green Onion Green onions are often planted to keep flea beetles off brassicas, but little research supports it and some contradicts it. UMN Extension ↗
With Marigold Marigolds are often planted to keep flea beetles off brassicas, but little research supports it and some contradicts it. UMN Extension ↗

Safety for pets and children

Cats No information in our sources
Dogs No information in our sources
Horses Listed as a problem for horses (NC State Extension)
Children No information in our sources

If a pet or child eats part of this plant, call your vet or poison control.

Read from NC State Extension ↗.

"No information" means our sources do not say, not that the plant is harmless. A non-toxic listing is not a reason to let anyone eat a plant.

Pests and diseases

No pest or disease notes for Kohlrabi yet.

Check the label and your local extension service before using any product.

Where this comes from

category NC State Extension ↗ Listed in Table 16-4, "Garden Planting Calendar for Annual Vegetables, Fruits, and Herbs"
climate requirement NC State Extension ↗ Toolbox: kohlrabi can "tolerate frost but not a hard freeze". No zones: an annual has no winter to survive (see the header)
days to maturity NC State Extension ↗ Table 16-4: T=22-32, S=50-60; the from-seed low end
direct sow weeks rel last frost cmg.extension.colostate.edu ↗ CSU #720 (Colorado) hardy class, a class-wide figure: as early as 2-4 weeks before the last frost; Table 1 gives kohlrabi no transplant age
family npgsweb.ars-grin.gov ↗ GRIN page: Brassica oleracea L. var. gongylodes L.
frost hardiness cmg.extension.colostate.edu ↗ CSU #720 (Colorado) hardy class lists kohlrabi
indoor start weeks extension.unh.edu ↗ UNH (New Hampshire) table: 4-6 weeks from seed to transplant; the top of the range
life cycle NC State Extension ↗ Toolbox Life Cycle: Biennial; recorded as annual, as migration 0027 did for biennials picked in their first season
life cycle NC State Extension ↗ Toolbox Life Cycle: Biennial; recorded as annual, as migration 0027 did for biennials picked in their first season
maturity counted from NC State Extension ↗ The 0069 row took NC State (North Carolina) Table 16-4's S=50-60, not T=22-32; CSU #720 (Colorado) gives 50 unmarked
min soil depth in NC State Extension ↗ Not in Table 18-1; 8 in as kale (8), the small-plant brassica in that table. Derived. A group figure, as every ch. 18 depth is
min soil temp f cmg.extension.colostate.edu ↗ CSU #720 (Colorado) Table 1: kohlrabi germination minimum 40°F
space requirement NC State Extension ↗ Table 16-4 distance between plants: 4 in. The table publishes no row distance, so rows equal plants -- the square spacing of an intensive bed
species NC State Extension ↗
sunlight NC State Extension ↗ Toolbox Light: Full sun (6 or more hours of direct sunlight a day)
toxicity NC State Extension ↗ toxic for horse from the page's "Problem for" listing.
transplant weeks rel last frost extension.unh.edu ↗ UNH (New Hampshire) table: kohlrabi 4 weeks before last frost
water frequency days UMN Extension ↗ UMN "Growing kohlrabi": "One inch of rainfall per week is good." and "If your soil is sandy, water more often than once a week."