Kohlrabi in Zone 6a & 6b
Brassica oleracea (Gongylodes group)
Yes, kohlrabi grows in zones 6a and 6b. Start seeds indoors Mar 21–Mar 28 and plant out Apr 11–Apr 18. For a fall crop, plant out Aug 7–Aug 21.
When to plant kohlrabi in zone 6b
Zones 6a and 6b share the same average frost dates, so this page covers both.
Method: Either: Start indoors for an earlier harvest, or direct-sow outside for less fuss. Either works.
| Window | Spring window |
|---|---|
| Start indoors | Mar 21–Mar 28 |
| Direct sow / transplant outside | Apr 11–Apr 18 |
| Estimated harvest | Jun 5–Jun 12 (~55 days after planting) |
| Window | Fall window |
|---|---|
| Start indoors | Not typically started indoors |
| Direct sow / transplant outside | Aug 7–Aug 21 |
| Estimated harvest | Oct 1–Oct 15 (~55 days after planting) |
Spacing: 4 per square foot (square-foot-gardening spacing). Mature height: 1-1.5 ft.
Fall window: the last sowing date is the average first frost minus days to maturity, the method in Purdue Extension's fall garden guide, which lists kohlrabi for late-summer planting.
Plant alongside it in zone 6b
These go outside within two weeks of kohlrabi in zone 6b, so one planting day can cover them.
- OnionApr 4–Apr 11
- RadishMar 28–Apr 4
- CarrotApr 4–Apr 11
- CabbageApr 11–Apr 18
- LettuceApr 11–Apr 18
- BroccoliApr 11–Apr 18
Kohlrabi looks like nothing else in the garden: a pale green or purple bulb that swells right at the soil line, with leaves shooting out of it like a small alien plant. It's mild, crisp, and closer to a cross between broccoli stem and jicama than anything most people expect from a brassica.
How kohlrabi fits zone 6's season
Zone 6b's frost-free window runs about 173 days, from April 25 to October 15. Kohlrabi needs about 55 days from sowing to first harvest.
Kohlrabi planting windows in every zone
Zone 6b is highlighted. Useful for comparing against a neighbouring zone, or for a garden somewhere else.
| Zone | Start indoors | Sow or plant out | Harvest |
|---|---|---|---|
| 2a & 2b | Apr 15–Apr 22 | May 6–May 13 | Jun 30–Jul 7 |
| 3a & 3b | Apr 25–May 2 | May 16–May 23 | Jul 10–Jul 17 |
| 4a & 4bSpring window | Apr 10–Apr 17 | May 1–May 8 | Jun 25–Jul 2 |
| Fall window | Not usually | Jul 13–Jul 27 | Sep 6–Sep 20 |
| 5a & 5bSpring window | Apr 5–Apr 12 | Apr 26–May 3 | Jun 20–Jun 27 |
| Fall window | Not usually | Jul 28–Aug 11 | Sep 21–Oct 5 |
| 6a & 6bSpring window (your zone) | Mar 21–Mar 28 | Apr 11–Apr 18 | Jun 5–Jun 12 |
| Fall window | Not usually | Aug 7–Aug 21 | Oct 1–Oct 15 |
| 7a & 7bSpring window | Mar 6–Mar 13 | Mar 27–Apr 3 | May 21–May 28 |
| Fall window | Not usually | Aug 17–Aug 31 | Oct 11–Oct 25 |
| 8a & 8bSpring window | Feb 18–Feb 25 | Mar 11–Mar 18 | May 5–May 12 |
| Fall window | Not usually | Sep 2–Sep 16 | Oct 27–Nov 10 |
| 9a & 9bSpring window | Jan 11–Jan 18 | Feb 1–Feb 8 | Mar 28–Apr 4 |
| Fall window | Not usually | Sep 27–Oct 11 | Nov 21–Dec 5 |
| 10a & 10bSpring window | Dec 26–Jan 2 | Jan 16–Jan 23 | Mar 12–Mar 19 |
| Fall window | Not usually | Oct 12–Oct 26 | Dec 6–Dec 20 |
| 11a & 11bFall window | Not usually | Oct–Feb | ~55 days after planting |
Harvest dates are about 55 days after the sow or plant-out date, not after starting seeds indoors.
Zone 2 sows before zone 3 here, which looks wrong and is not. USDA zones rank winter cold, not season length, and zone 2 is mostly interior Alaska, where hard winters come with warm summers. More on what a zone measures.
Good companions
- Beet: Compatible nutrient needs; common bed-sharing pair.
Where to buy kohlrabi seeds
True Leaf Market · Burpee · High Mowing Organic Seeds (each supplier's kohlrabi seeds)
Varieties we recommend, and where to get them:
- Kolibri: Cornell rates it 4.7 stars, a vivid purple hybrid with crisp, nearly fiberless white flesh at 43-45 days. Buy: High Mowing Organic Seeds Full notes
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing kohlrabi" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 6b calendar · Plan your beds in the Garden Designer →
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Growing Kohlrabi in USDA zone 6b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
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