Vegetable / Cool season
Kohlrabi
The odd space-alien stem kids will eat raw
Plant out byApr 13zone 6
- Family
- Mustard (Brassicaceae)
- Sun
- Full sun (6+ h)
- Difficulty
- Some care
- Days to harvest
- 45-60 days
- Spacing
- 6 in apart, rows 12 in
- Pot size
- 3 gal pot (fine in pots)
- Frost
- Half-hardy
- Start
- Either
- Water
When to plant
Showing .
Averages for a typical garden in the region. Your local frost dates may differ by 2-3 weeks, check a local source.Too late this year (try fall)
In zone 6, start seeds indoors Feb 23 to Mar 9; plant out Mar 23 to Apr 13; sow again for fall Aug 11 to Sep 8. Average last frost Apr 20, first fall frost Oct 20.
Units
Kohlrabi looks like a vegetable a kid would draw from memory. It is a round stem the size of a tennis ball, with leaves sticking out like antennas. Peeled and sliced, it tastes like a crisp, mild broccoli stem. Kids who refuse broccoli will often eat it raw with a pinch of salt.
The catch is timing. Kohlrabi wants cool weather from start to finish. Temperatures above about 75 degrees F slow it down and turn the swollen stem tough and woody, and dry spells do the same. A long cold snap below 45 degrees F can push young plants to flower instead. That leaves a narrow spring window. Start seeds indoors 6 to 8 weeks before your last frost, and set them out 1 to 4 weeks before it. Fall is often easier. Transplants go in about 6 weeks before the first frost, and the cold sweetens them.
Space plants about 6 inches apart. That tight spacing makes kohlrabi a good fit for one square of a raised bed or a wide pot. Water on a steady schedule. Pick when the bulb reaches 2 to 3 inches across, because bigger ones get woody fast. Utah State suggests 3 to 5 feet of row per person for fresh eating, which is only a handful of plants. Flea beetles and cabbage worms find it just as quickly as they find the kale.
Things to consider
- Each plant gives one bulb and then it is finished. For a steady supply, sow a few every two to three weeks instead of a whole row at once. A short row fits easily between slower crops.
- Giant varieties such as 'Gigante' can take around 130 days, while 'Kolibri' and 'Winner' are closer to 45. Check the packet before you count on a quick crop. Utah State lists 'Quickstar' at about 40 days and 'Grand Duke' at about 50.
- Rotate it out of any spot where cabbage family crops grew in the last 2 to 3 years. Clubroot and black rot build up in the soil over time. Moving the crop to fresh ground each year is the simplest defense, even in a small bed where it only shifts a few feet.
Good neighbours
Keep apart
Pests to watch for
Flea beetlesCabbage wormsCabbage loopersAphids
Questions about growing kohlrabi
What part of kohlrabi do you eat?
Mostly the swollen stem, peeled. The young leaves cook up like collards or kale. Older outer leaves are tough, so use the small ones near the top. Purple types have purple skin, but the flesh inside is pale and tastes the same. Grated raw, it makes a crunchy slaw.
How should I store kohlrabi?
Twist off the leaves and keep the bulbs cold and humid. Utah State Extension lists about 2 to 3 weeks at 32 degrees F with high humidity. A home fridge runs warmer, so plan to eat them sooner. The leaves wilt fast, so store them separately and cook them within a few days.
Can I sow kohlrabi straight into the garden?
For fall, yes: direct sow about 8 to 10 weeks before the first frost. In spring, the Old Farmer's Almanac recommends transplants, since late seedlings often meet summer heat before they size up. Seeds sprout in 4 to 7 days. Thin direct-sown seedlings to 5 to 8 inches apart once they are up.
Save this crop
Pin it to a garden board so it is there when planting time comes round.
Similar crops
Sources
General guidance for home gardens. Frost dates are averages for a zone or region; check a local source (in the US your county extension office) for local timing.