Kale in Zone 4a & 4b
Brassica oleracea
Yes, kale grows in zones 4a and 4b. Start seeds indoors Apr 3–Apr 10 and plant out Apr 24–May 1. For a fall crop, plant out Jul 8–Jul 22.
When to plant kale in zone 4b
Zones 4a and 4b 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 | Apr 3–Apr 10 |
| Direct sow / transplant outside | Apr 24–May 1 |
| Estimated harvest | Jun 23–Jun 30 (~60 days after planting) |
| Window | Fall window |
|---|---|
| Start indoors | Not typically started indoors |
| Direct sow / transplant outside | Jul 8–Jul 22 |
| Estimated harvest | Sep 6–Sep 20 (~60 days after planting) |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 1-2 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 kale for late-summer planting.
Plant alongside it in zone 4b
These go outside within two weeks of kale in zone 4b, so one planting day can cover them.
- RadishApr 17–Apr 24
- CarrotApr 24–May 1
- CabbageMay 1–May 8
- LettuceMay 1–May 8
- BeetApr 24–May 1
- Broccoli Rabe (Raab)Apr 24–May 1
Kale is about as low-maintenance as vegetables get, and one of the few that improves with cold, a hard frost sweetens the leaves rather than ruining them. It can be started indoors or direct-seeded, and either way it tends to outlast most other greens into late fall.
How kale fits zone 4's season
Zone 4b's frost-free window runs about 128 days, from May 15 to September 20. Kale needs about 60 days from sowing to first harvest.
Kale planting windows in every zone
Zone 4b 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 8–Apr 15 | Apr 29–May 6 | Jun 28–Jul 5 |
| 3a & 3b | Apr 18–Apr 25 | May 9–May 16 | Jul 8–Jul 15 |
| 4a & 4bSpring window (your zone) | Apr 3–Apr 10 | Apr 24–May 1 | Jun 23–Jun 30 |
| Fall window | Not usually | Jul 8–Jul 22 | Sep 6–Sep 20 |
| 5a & 5bSpring window | Mar 29–Apr 5 | Apr 19–Apr 26 | Jun 18–Jun 25 |
| Fall window | Not usually | Jul 23–Aug 6 | Sep 21–Oct 5 |
| 6a & 6bSpring window | Mar 14–Mar 21 | Apr 4–Apr 11 | Jun 3–Jun 10 |
| Fall window | Not usually | Aug 2–Aug 16 | Oct 1–Oct 15 |
| 7a & 7bSpring window | Feb 27–Mar 6 | Mar 20–Mar 27 | May 19–May 26 |
| Fall window | Not usually | Aug 12–Aug 26 | Oct 11–Oct 25 |
| 8a & 8bSpring window | Feb 11–Feb 18 | Mar 4–Mar 11 | May 3–May 10 |
| Fall window | Not usually | Aug 28–Sep 11 | Oct 27–Nov 10 |
| 9a & 9bSpring window | Jan 4–Jan 11 | Jan 25–Feb 1 | Mar 26–Apr 2 |
| Fall window | Not usually | Sep 22–Oct 6 | Nov 21–Dec 5 |
| 10a & 10bFall window | Aug–Dec | Sep–Jan | ~60 days after transplanting |
Harvest dates are about 60 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
- Onion: Onion scent is reputed to confuse cabbage moths that target kale. The research behind this is real but garlic-specific (field trials intercropping garlic with cabbage reduced diamondback moth damage): onion hasn't been tested the same way, so treat the onion version as a reasonable extrapolation, not a directly measured result.
Where to buy kale seeds
Botanical Interests · True Leaf Market · Burpee · High Mowing Organic Seeds (each supplier's kale seeds)
Varieties we recommend, and where to get them:
- Red Russian: Cornell's Vegetable Varieties for Gardeners database has it as the most-reviewed kale in their system at 33 reviews and a 4.4-star rating, with oak-shaped, gray-green leaves and deep-purple veins that are noticeably more tender than curly types like Winterbor. Buy: Botanical Interests · True Leaf Market · Burpee · High Mowing Organic Seeds Full notes
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing kale" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
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Growing Kale in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
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