Brussels Sprouts in Zone 4a & 4b
Brassica oleracea
Yes, Brussels sprouts grow in zones 4a and 4b. Start seeds indoors Apr 3–Apr 10 and plant out May 1–May 8.
When to plant Brussels sprouts in zone 4b
Zones 4a and 4b share the same average frost dates, so this page covers both.
Method: Start indoors: Start indoors from seed, then transplant outside. It needs a head start most zones can't give it by direct-sowing alone.
| Start indoors | Apr 3–Apr 10 |
|---|---|
| Direct sow / transplant outside | May 1–May 8 |
| Estimated harvest | Aug 4–Aug 11 (~95 days after transplanting) |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 2-3 ft.
Plant alongside it in zone 4b
These go outside within two weeks of Brussels sprouts 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
- BroccoliMay 1–May 8
- Flower SproutsMay 1–May 8
Brussels sprouts take longer to mature than almost anything else in the vegetable garden, close to a full season from seed to harvest, and they're one of the few crops that improve with a touch of frost, which converts starches to sugars and softens the bitterness the vegetable is known for.
How Brussels sprouts fit zone 4's season
Zone 4b's frost-free window runs about 128 days, from May 15 to September 20. Brussels sprouts need about 95 days from transplant to first harvest.
Brussels Sprouts 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 |
|---|---|---|---|
| 3a & 3b | Apr 18–Apr 25 | May 16–May 23 | Aug 19–Aug 26 |
| 4a & 4b (your zone) | Apr 3–Apr 10 | May 1–May 8 | Aug 4–Aug 11 |
| 5a & 5b | Mar 29–Apr 5 | Apr 26–May 3 | Jul 30–Aug 6 |
| 6a & 6b | Mar 14–Mar 21 | Apr 11–Apr 18 | Jul 15–Jul 22 |
| 7a & 7bSpring window | Feb 27–Mar 6 | Mar 27–Apr 3 | Jun 30–Jul 7 |
| Fall window | Jun 10–Jun 24 | Jul 8–Jul 22 | Oct 11–Oct 25 |
| 8a & 8bSpring window | Feb 11–Feb 18 | Mar 11–Mar 18 | Jun 14–Jun 21 |
| Fall window | Jun 26–Jul 10 | Jul 24–Aug 7 | Oct 27–Nov 10 |
| 9a & 9bSpring window | Jan 4–Jan 11 | Feb 1–Feb 8 | May 7–May 14 |
| Fall window | Jul 21–Aug 4 | Aug 18–Sep 1 | Nov 21–Dec 5 |
| 10a & 10bFall window | Jul–Sep | Sep–Nov | ~95 days after transplanting |
Harvest dates are about 95 days after the sow or plant-out date, not after starting seeds indoors.
Good companions
- Onion: Onion scent is reputed to confuse cabbage moths that target brassicas. 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 Brussels sprout seeds
Botanical Interests · Burpee · High Mowing Organic Seeds (each supplier's Brussels sprout seeds)
Varieties we recommend, and where to get them:
- Diablo, Divino, and Nautic: A University of New Hampshire Extension variety trial (2013-2021, published 2022) found these three cultivars had the highest yields, most uniform sprouts, and best resistance to Alternaria leaf spot among the varieties tested. Buy: High Mowing Organic Seeds Full notes
- Long Island Improved: A standard garden variety since the 1800s, open-pollinated so you can save your own seed, unlike the F1 hybrids above. Buy: Botanical Interests · Burpee Full notes
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing Brussels sprouts" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 4b calendar · Plan your beds in the Garden Designer →
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Growing Brussels Sprouts in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
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