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When to plant grass seed in zone 4a

In zone 4a, where the last spring frost typically comes around May 13, sow outdoors April 1 to 15. For a fall crop, plant August 17 to 31.

The zone 4a schedule for grass seed

Sow outdoors
April 1 to 15
Plant for a fall crop
August 17 to 31

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 grass seed.

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 grass seed

Set your ZIP code at the top of the page and we will work out when to plant grass seed 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

Grass Seed in zone 4a cities

CityTypical last frostPlantFall
Fargo, NDMay 10Mar 29 to Apr 12Aug 19 to Sep 2
Bismarck, NDMay 14Apr 2 to 16Aug 16 to 30
Grand Forks, NDMay 10Mar 29 to Apr 12Aug 20 to Sep 3

How to grow grass seedAll zonesGrass Seed in zone 3bGrass Seed in zone 4bAbout zone 4a

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