DibbleWhen to plant leeks 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 leeks in Zone 4
| Task | Window |
|---|---|
| Start seeds indoors | Mar 1 to Mar 15 |
| Transplant | Apr 26 to May 10 |
| Estimated harvest | Aug 24 to Oct 8 |
The harvest estimate counts 120 days to maturity, then a picking window of about 45 days. These windows use typical frost dates for Zone 4; Dibble pins them to your exact ZIP code.
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Leek in a Zone 4 season
Zone 4 gives about 134 frost-free days. Leek needs roughly 120 days from transplant. That leaves about 14 days of slack, which is tight. Start indoors where you can and do not sow late.
How to grow leeks
Start indoors 10 weeks before last frost. Transplant into a deep hole and hill soil up the stem to blanch the white shanks.
Companion plants
Good neighbors for Leek:
Better kept apart:
Leek in other zones
Not in Zone 4? Pick your zone for the same dated windows.
Keep exploring
Leek: 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.