Kohlrabi
German Turnip, Turnip Cabbage, Vienna, Kohl-Rabi, Cabbage Turnip, Cabbage-Turnip
Direct sow or transplant 4–6 weeks before last frost. The edible part is the swollen stem, not a root. Harvest when bulb is 2–3" in diameter — larger bulbs become tough and woody. Purple varieties are more cold-hardy and slightly sweeter. Excellent for succession planting; fast enough for two crops in spring and fall. Space 6" apart for full-size bulbs.
- Germination
- 5–10 days
- Soil temperature
- 7–29 °C
- Harvest after sowing
- 45–60 days
- Spacing
- 13–20 cm
When to plant kohlrabi
Sow outdoors 2–4 weeks before your last spring frost.
Dashed line: typical last spring frost in zone 7 (Apr 5). Zone dates are averages; most of the UK is zone 8–9, central Europe 6–7 and the Baltics and Scandinavia 4–6. In the app, Tomatograph uses your garden's own frost dates.
How to grow kohlrabi
- 1
Sow
Sow 6 mm deep 2–4 weeks before the last frost, and again in late summer for an autumn crop.
- 2
Thin
Thin to about 15 cm apart for full-size stems.
- 3
Water
Keep growth steady with regular watering; checks in growth make the swollen stem woody.
- 4
Harvest
Pull when the swollen stem is 5–8 cm across, 45–60 days after sowing. Larger ones turn tough. Purple types are slightly hardier and sweeter.
Growing conditions
Light
Full sun
Water
Medium water
Temperature
4–24 °C
Frost tolerance
Frost-hardy — tolerates frost
Days to maturity
45–65 days
Ideal soil pH
7–7.5
How Tomatograph watches your kohlrabi
Tomatograph checks your local forecast every morning and only speaks up when one of these applies to your garden.
- First frost within 14 daysReminder to mulch the roots before winter.
- 3 days at 35 °C or aboveHeat-wave alert while plants are flowering or fruiting: shade and water early.
- Humidity above 80% for 48 hoursCheck for clubroot, which thrives in those conditions.
- Within a week of maturityHarvest-window reminder based on when you planted.
Kohlrabi questions
- When should I plant kohlrabi?
- Sow outdoors 2–4 weeks before your last spring frost.
- How long do kohlrabi seeds take to germinate?
- Usually 5–10 days at a soil temperature of 7–29 °C.
- How long until I can harvest kohlrabi?
- About 45–60 days after sowing, depending on variety and weather.
- How far apart should I plant kohlrabi?
- Allow 13–20 cm between plants.
- What grows well with kohlrabi?
- Good neighbours include onion, lettuce, beet, cucumber.
Growing guide written by Tomatograph. Planting figures from openplantdb (CC0 1.0). Zone frost dates are averages from openplantdb (CC0 1.0).