DibbleWhen to plant broccoli in Zone 4
In Zone 4, the last spring frost usually passes around May 10 and the first fall frost arrives around September 21, leaving about 134 frost-free days. The windows below are computed from those frost dates, with the same math the Dibble app uses.
Cool climate with a brief warm window. Indoor starts and season extension help.
Planting windows for broccoli in Zone 4
| Task | Window |
|---|---|
| Start seeds indoors | Mar 29 to Apr 12 |
| Transplant | Apr 26 to May 10 |
| Estimated harvest | Jun 30 to Jul 21 |
The harvest estimate counts 65 days to maturity, then a picking window of about 21 days. These windows use typical frost dates for Zone 4; Dibble pins them to your exact ZIP code.
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Broccoli in a Zone 4 season
Zone 4 gives about 134 frost-free days. Broccoli needs roughly 65 days from transplant. That leaves about 69 days of slack, so there is room for a late start or a second planting.
How to grow broccoli
Start seeds indoors about 4 weeks before planting out, timing it so the heads form in cool weather. Cut the central head, then enjoy side shoots for weeks. Heat makes the heads loose and uneven.
Companion plants
Good neighbors for Broccoli:
Better kept apart:
Broccoli in other zones
Not in Zone 4? Pick your zone for the same dated windows.
Keep exploring
Broccoli: the full growing guide · The Zone 4 planting calendar · Every crop and zone
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Dates are estimates based on typical frost dates for the zone. Your yard has its own microclimate, so use them as a starting point and adjust as you learn your space.