When to plant kohlrabi by city
Start kohlrabi indoors 4–6 weeks before your last frost, plant them out 2–4 weeks before your last frost, or sow seed outdoors 2–4 weeks before your last frost. For a fall crop, sow 8–10 weeks before your first fall frost. Here is what that means for 2027 in cities across the US, using each city’s average frost dates (NOAA 1991–2020). Pick the city with the climate most like yours, or enter your ZIP code above.
| City | Last frost | Start indoors | Plant out | Sow outdoors | Fall crop |
|---|---|---|---|---|---|
| Seattle, WA (9a) | Mar 13 | Jan 30 – Feb 13 | Feb 13–27 | Feb 13–27 | Sep 8–22 |
| Portland, OR (8b) | Feb 25 | Jan 14–28 | Jan 28 – Feb 11 | Jan 28 – Feb 11 | Sep 22 – Oct 6 |
| Sacramento, CA (9b) | Jan 12 | Dec 1–15 | Dec 15–29 | Dec 15–29 | Oct 7–21 |
| Phoenix, AZ (10a) | Jan 5 | Nov 24 – Dec 8 | Dec 8–22 | Dec 8–22 | Oct 25 – Nov 8 |
| Salt Lake City, UT (7b) | Mar 31 | Feb 17 – Mar 3 | Mar 3–17 | Mar 3–17 | Aug 30 – Sep 13 |
| Denver, CO (6a) | Apr 30 | Mar 19 – Apr 2 | Apr 2–16 | Apr 2–16 | Aug 3–17 |
| Dallas, TX (8b) | Mar 2 | Jan 19 – Feb 2 | Feb 2–16 | Feb 2–16 | Sep 20 – Oct 4 |
| Minneapolis, MN (5a) | Apr 23 | Mar 12–26 | Mar 26 – Apr 9 | Mar 26 – Apr 9 | Aug 7–21 |
| Kansas City, MO (6b) | Apr 4 | Feb 21 – Mar 7 | Mar 7–21 | Mar 7–21 | Aug 24 – Sep 7 |
| Chicago, IL (6b) | Apr 10 | Feb 27 – Mar 13 | Mar 13–27 | Mar 13–27 | Aug 27 – Sep 10 |
| Columbus, OH (6b) | Apr 20 | Mar 9–23 | Mar 23 – Apr 6 | Mar 23 – Apr 6 | Aug 15–29 |
| Nashville, TN (7b) | Apr 1 | Feb 18 – Mar 4 | Mar 4–18 | Mar 4–18 | Aug 22 – Sep 5 |
| Atlanta, GA (8a) | Mar 24 | Feb 10–24 | Feb 24 – Mar 10 | Feb 24 – Mar 10 | Aug 30 – Sep 13 |
| Raleigh, NC (8a) | Mar 28 | Feb 14–28 | Feb 28 – Mar 14 | Feb 28 – Mar 14 | Aug 30 – Sep 13 |
| Philadelphia, PA (7b) | Mar 30 | Feb 16 – Mar 2 | Mar 2–16 | Mar 2–16 | Sep 8–22 |
| Boston, MA (7a) | Apr 4 | Feb 21 – Mar 7 | Mar 7–21 | Mar 7–21 | Aug 31 – Sep 14 |
In frost-free parts of Florida, southern California and the Gulf Coast, timing is about heat instead: grow kohlrabi from fall through winter.
Kohlrabi spacing
In a square-foot bed, plant 4 per square foot. In traditional rows, space plants about 6 inches apart with 12 inches between rows.
Harvest at tennis-ball size, before it turns woody.
How to grow kohlrabi
Kohlrabi grows a crisp, round swollen stem that tastes like a mild, sweet broccoli stalk. It is quick, compact and easy, a good crop for small beds and for gardeners who want something a little different. Pick it young, before it turns woody.
Sun and soil
Full sun and fertile, well-drained soil with a pH of about 6.0–7.0. Roots are shallow, so water often enough to keep the soil evenly moist, about 1–2 inches a week.
Planting
- Sow ¼–½ inch deep 2–4 weeks before the last spring frost, once soil reaches 45°F, or start indoors 4–6 weeks before transplanting.
- Thin or space to 6 inches apart in rows 12 inches apart.
- Avoid transplanting into a long cold spell; extended temperatures below about 45°F can make young plants bolt.
- For fall, sow 8–10 weeks before the first fall frost.
Care
- Keep moisture steady; dry spells make the stems tough and fibrous.
- Side-dress with nitrogen about 3 weeks after thinning or transplanting.
- Growth slows above about 75°F. Mulch to keep roots cool if spring turns hot.
Harvest
Harvest when the swollen stem is 2–3 inches across, about tennis-ball size. Cut below the bulb at soil level. Peel off the tough outer skin before eating; young leaves can be cooked like kale. Giant varieties stay tender at larger sizes.
Common problems
- Woody stems: Caused by harvesting late or by water stress. Pick at 2–3 inches and water steadily.
- Cabbageworms and loopers: Row cover after planting, and Bt or hand-picking for caterpillars.
- Flea beetles: Holes in seedling leaves. Cover seedlings until they are well established.
Varieties to try
- 'Early White Vienna' — pale green, quick and reliable
- 'Purple Vienna' — purple skin, white flesh
- 'Kossak' — giant hybrid that stays tender, stores well
- 'Quickstar' — fast and uniform
Crop rotation
Kohlrabi belong to the cabbage family (Brassicaceae). Clubroot and cabbage pests build up in the soil. Rotate for at least 3 years. Relatives that count as the same family for rotation: broccoli, cauliflower, cabbage, kale, brussels sprouts, radish, turnip, arugula, bok choy.
Frequently asked questions
When should I plant kohlrabi?
What grows well with kohlrabi?
How far apart should I plant kohlrabi?
How long do kohlrabi take to grow?
Can kohlrabi handle frost?
Sources
- Frost dates: NOAA National Centers for Environmental Information, U.S. Climate Normals 1991–2020.
- Hardiness zones: 2023 USDA Plant Hardiness Zone Map, USDA-ARS and PRISM Climate Group, Oregon State University.
- Planting windows and spacing: Vegetable Planting Guide (GardenNotes #720), Colorado State University Extension, and other land-grant extension guides.
- Gardening with Companion Plants (EM128E), Linda Chalker-Scott, Washington State University Extension, 2023
- Brassica flea beetles, UMass Amherst Vegetable Program
- Trap Cropping, Washington State University Extension Master Gardener Program
- Trap cropping: a review of the state of the art, Sarkar et al., 2018 (open-access review)
- Kohlrabi in the Garden — Utah State University Extension