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When to plant grass seed in zone 4b

In zone 4b, where the last spring frost typically comes around May 8, sow outdoors March 27 to April 10. For a fall crop, plant August 20 to September 3.

The zone 4b schedule for grass seed

Sow outdoors
March 27 to April 10
Plant for a fall crop
August 20 to September 3

From the median frost dates of the NOAA stations assigned to the 1,164 ZIP codes in zone 4b, 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 4b

Zones are based on winter cold, not on frost dates, so the last spring frost varies a lot within a zone. Across zone 4b, the typical last frost ranges from about May 1 in the earliest tenth of ZIP codes to May 25 in the latest tenth, and the first fall frost from September 22 to October 8. For a typical place in the zone:

  • April 26Risky: a later frost happens in 9 years out of 10
  • May 8Typical: frost after this date in half of years
  • May 22Safe: 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 4b cities

CityTypical last frostPlantFall
Rochester, MNApr 30Mar 19 to Apr 2Aug 25 to Sep 8
Duluth, MNMay 6Mar 25 to Apr 8Aug 28 to Sep 11
Lakeville, MNMay 2Mar 21 to Apr 4Aug 24 to Sep 7
St. Cloud, MNMay 7Mar 26 to Apr 9Aug 19 to Sep 2
Eau Claire, WIMay 8Mar 27 to Apr 10Aug 23 to Sep 6
Great Falls, MTMay 19Apr 7 to 21Aug 13 to 27

How to grow grass seedAll zonesGrass Seed in zone 4aGrass Seed in zone 5aAbout zone 4b

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