How to grow kohlrabi
Pick bulbs at tennis-ball size; bigger ones turn woody.
Your kohlrabi dates
Companions
Keep apart from
Rotation and family
Kohlrabi belongs to the brassicas (Brassicaceae). Hungry for nitrogen; clubroot spores persist in soil for years.
In a four-bed crop rotation it goes in the leaf & brassica bed. Avoid growing it where any brassicas grew in the last three years.
Sow a fresh batch every 14 days for a steady supply. The succession planting calculator lists the dates.
When to plant kohlrabi by zone
| Zone | Start indoors | Sow / plant out | Sow for fall |
|---|---|---|---|
| 3 | Apr 8 – Apr 22 | Apr 22 – Jun 3 | Jul 8 – Jul 29 |
| 4 | Mar 31 – Apr 14 | Apr 14 – May 26 | Jul 18 – Aug 8 |
| 5 | Mar 19 – Apr 2 | Apr 2 – May 14 | Jul 30 – Aug 20 |
| 6 | Mar 9 – Mar 23 | Mar 23 – May 4 | Aug 11 – Sep 1 |
| 7 | Feb 25 – Mar 11 | Mar 11 – Apr 22 | Aug 21 – Sep 11 |
| 8 | Feb 12 – Feb 26 | Feb 26 – Apr 9 | Sep 3 – Sep 24 |
| 9 | Jan 11 – Jan 25 | Jan 25 – Mar 8 | Sep 24 – Oct 15 |
| 10 | Dec 21 – Jan 4 | Jan 4 – Feb 15 | Oct 9 – Oct 30 |
Based on typical frost dates for each zone; b half-zones run about a week earlier in spring. Zones 11–13 are frost-free in most years.
Kohlrabi questions
When should I plant kohlrabi?
Plant kohlrabi outdoors 4 weeks before your last spring frost. Start seeds indoors about 6 weeks before your last frost. For a fall crop, sow about 10 weeks before your first fall frost.
How far apart should I plant kohlrabi?
About 6 inches apart, or 4 per square foot in a square foot garden.
What grows well with kohlrabi?
Traditional companions include beet, lettuce, onion. Keep it away from strawberry, tomato.
How long does kohlrabi take to grow?
Typically 45–60 days from sowing to first harvest, depending on variety and weather.