Vegetable · Brassica
Kohlrabi
Brassica oleracea var. gongylodesAn odd-looking but fast, easy brassica that swells into a crisp, mild bulb sitting just above the soil. It is far more forgiving than most cabbage relatives and matures quickly enough for two crops a year. The one rule: harvest before the bulb outgrows a tennis ball, or it turns woody.
Sow depth
½ in
Spacing
8 in · rows 12 in
Sun
Full sun
Germination
5–10 days
Time to harvest
45–60 days
Difficulty
Easy
When to sow kohlrabi
- Sow from about 3 weeks before your last expected frost until around your last expected frost.
- Sow from about 9 weeks before the first expected autumn frost until about 6 weeks before the first expected autumn frost.
Direct sow thinly — kohlrabi grows fast and dislikes root disturbance.Sow in shallow drills once the soil has lost its winter chill.Thin seedlings early so bulbs have room to swell evenly.
Keep it moving — steady moisture prevents bulbs from turning tough.Weed regularly while plants are small and easily outcompeted.Mulch lightly to keep the root zone consistently cool and damp.
Pull at golf- to tennis-ball size — smaller bulbs stay tender and mild.Twist off the bulb at soil level, trimming leaves for cooking too.Check plants often; oversized bulbs quickly turn fibrous and bland.
Companion plants
Onions planted between kohlrabi confuse cabbage-root-fly by masking the brassica scent.
Watch out for
Cabbage root fly — Larvae tunnel into stems near the soil line in spring. Fit a collar of cardboard or fabric flush around each stem at planting.