How to grow kohlrabi
Brassica oleracea (Gongylodes) · Brassicaceae · Vegetable
When to plant kohlrabi: the short answer
Start seeds indoors about 5 weeks before your last spring frost; plant out about 3 weeks before it; sow outdoors about 3 weeks before the last frost; for a fall crop, sow about 8 weeks before your first fall frost. Seeds germinate in soil from 45 to 85°F, fastest near 70°F.
Cold winters (zone 5): plant out Apr 2 – Apr 19, or sow Jul 31 – Aug 17 for a fall crop. Mild winters (zone 9): sow Sep 25 – Oct 12 for fall and winter harvests; the spring window (Jan 23 – Feb 9) closes before the summer heat. Skip the hottest months for kohlrabi. See every zone.
Kohlrabi is a cool-season vegetable in the Brassicaceae family, grown either from a direct sowing or from transplants. It wants full sun, though it tolerates a little afternoon shade in hot regions and steady, even moisture. From sowing to first pick is about 45–60 days. It handles frost well and a light freeze often improves the flavour.
Grower’s note: Harvest the swollen stem at 2-3 in across - bigger bulbs turn woody. Fast enough to succession sow every couple of weeks in spring and again for fall.
Sowing
Sow about 0.5″ deep, into soil between 45–85°F — germination is quickest near 70°F. It comes up fast (5–10 days). For an early crop, start seed indoors about 5 weeks before your last spring frost and grow it under bright light.
Spacing & layout
Give each plant about 6″ along the row with roughly 12″ between rows. On a square-foot grid that is 4 per square foot. Allow at least 12″ of loose, workable soil for the roots. It grows well in containers at least 10″ deep.
Fitting it to your season
As a cool-season crop, kohlrabi does its best growing in the mild weather of spring and fall and tends to bolt or turn bitter in summer heat. A second sowing in late summer, timed to mature as the weather cools, is usually the better crop of the year — and light frost only sweetens it.
Quick facts
Growth stages: how long kohlrabi takes to grow
From sowing to first harvest takes roughly 45-60 days (6-9 weeks), with seedlings appearing after 5-10 days in soil around 70°F.
When to plant kohlrabi
When to plant kohlrabi by USDA zone
Dates worked out from each zone’s typical frost dates for 2026. Find your zone on the zone map, or pick your state below for dates from its own frost dates. Zones 11 and above are frost-free, so timing there depends on heat and rain instead.
| Zone | Last / first frost | Start indoors | Sow or plant out | Fall or second sowing |
|---|---|---|---|---|
| Zone 3 | May 15 / Sep 15 | Apr 3 – Apr 17 | Apr 17 – May 4 | Jul 11 – Jul 28 |
| Zone 4 | May 10 / Sep 25 | Mar 29 – Apr 12 | Apr 12 – Apr 29 | Jul 21 – Aug 7 |
| Zone 5 | Apr 30 / Oct 5 | Mar 19 – Apr 2 | Apr 2 – Apr 19 | Jul 31 – Aug 17 |
| Zone 6 | Apr 15 / Oct 15 | Mar 4 – Mar 18 | Mar 18 – Apr 4 | Aug 10 – Aug 27 |
| Zone 7 | Apr 5 / Oct 25 | Feb 22 – Mar 8 | Mar 8 – Mar 25 | Aug 20 – Sep 6 |
| Zone 8 | Mar 20 / Nov 5 | Feb 6 – Feb 20 | Feb 20 – Mar 9 | Aug 31 – Sep 17 |
| Zone 9 | Feb 20 / Nov 30 | Jan 9 – Jan 23 | Jan 23 – Feb 9 | Sep 25 – Oct 12 |
| Zone 10 | Jan 30 / Dec 15 | Dec 19 – Jan 2 | Jan 2 – Jan 19 | Oct 10 – Oct 27 |
Companions
Onion, Beet, Cucumber, Lettuce
Tomato, Pole Bean, strawberry, Bell Pepper
Common problems
Pests: cabbage worm, flea beetle, cabbage root maggot, aphids.
Diseases & disorders: clubroot, black rot.
Same family (Brassicaceae)
Rotate these so they don’t follow each other in the same bed year to year.
Questions gardeners ask
When should I plant kohlrabi?
Start seeds indoors about 5 weeks before your last spring frost; plant out about 3 weeks before it; sow outdoors about 3 weeks before the last frost; for a fall crop, sow about 8 weeks before your first fall frost. Seeds germinate in soil from 45 to 85°F. The table on this page gives dates for each USDA zone, and the planting calendar gives dates for your own state or ZIP code.
How long does kohlrabi take to grow?
About 45-60 days from sowing to the first harvest. Seeds germinate in 5-10 days, fastest in soil around 70°F.
How much sun does kohlrabi need?
It needs six or more hours of sun for the best growth, though four to six hours in partial shade is enough.
What soil pH does kohlrabi need?
A soil pH between 6.0 and 7.5. Test before adding lime or sulfur - see the soil pH and testing guide.
How far apart should I plant kohlrabi?
Space plants about 6 inches apart in rows 12 inches apart, or 4 per square foot in a square-foot bed. Sow seeds about ½ inch deep.
Can I grow kohlrabi in a container?
Yes. Use a container at least 10 inches deep with drainage holes and a good potting mix, and water more often than you would in the ground.
Figures are typical home-garden ranges from Cooperative Extension planting guides, cross-checked against multiple state sources. Your variety and conditions will vary.