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When to plant potatoes in zone 4a

In zone 4a, where the last spring frost typically comes around May 13, sow outdoors May 7 to 14.

The zone 4a schedule for potatoes

Sow outdoors
May 7 to 14
Soil warm enough (50°F), about
May 7
First harvest, roughly
July 31 to September 11

From the median frost dates of the NOAA stations assigned to the 739 ZIP codes in zone 4a, and the timing recommended by Cooperative Extension guides for potatoes.

Dates before the last frost assume the soil has thawed and is dry enough to work: a squeezed handful crumbles instead of sticking. After a late or wet spring, wait for that even if the date has passed.

Frost risk in zone 4a

Zones are based on winter cold, not on frost dates, so the last spring frost varies a lot within a zone. Across zone 4a, the typical last frost ranges from about May 6 in the earliest tenth of ZIP codes to May 24 in the latest tenth, and the first fall frost from September 20 to October 3. For a typical place in the zone:

  • April 30Risky: a later frost happens in 9 years out of 10
  • May 13Typical: frost after this date in half of years
  • May 27Safe: a later frost only 1 year in 10

Your dates for potatoes

Set your ZIP code at the top of the page and we will work out when to plant potatoes where you live, from the frost records of the nearest NOAA weather station. Your ZIP code is remembered on this device only.

Enter your ZIP code

Potatoes in zone 4a cities

CityTypical last frostPlantFall
Fargo, NDMay 10May 1 to 8—
Bismarck, NDMay 14May 3 to 10—
Grand Forks, NDMay 10May 5 to 12—

How to grow potatoesAll zonesPotatoes in zone 3bPotatoes in zone 4bAbout zone 4a

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