Kohlrabi in Zone 4a & 4b
Brassica oleracea (Gongylodes group)
When to plant kohlrabi in zone 4b
Zones 4a and 4b share the same average frost dates in our data, so this page covers both.
Method: Either: Start indoors for an earlier harvest, or direct-sow outside for less fuss. Kohlrabi tolerates either.
| Start indoors | Apr 10–Apr 17 |
|---|---|
| Direct sow / transplant outside | May 1–May 8 |
| Estimated harvest | Jun 25–Jul 2 (~55 days after planting) |
Spacing: 4 per square foot (square-foot-gardening spacing). Mature height: 1-1.5 ft.
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 4's season
Zone 4b's frost-free window runs about 128 days, from May 15 to September 20. Kohlrabi needs about 55 days from sowing to first harvest.
Good companions
- Beet: Compatible nutrient needs; common bed-sharing pair.
Where to buy kohlrabi seeds
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 4b calendar · Full companion planting guide · Full plant profile · Plan your beds in the Garden Designer →
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Growing Kohlrabi in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
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