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When to plant lettuce in zone 4a

In zone 4a, where the last spring frost typically comes around May 13, start lettuce indoors March 18 to April 1 and plant out May 6 to 20. For a fall crop, plant June 29 to August 3.

The zone 4a schedule for lettuce

Start seeds indoors
March 18 to April 1
Plant out
May 6 to 20
Sow outdoors
April 22 to 29
First harvest, roughly
June 5 to July 29
Plant for a fall crop
June 29 to August 3

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 lettuce.

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 lettuce

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

Lettuce in zone 4a cities

CityTypical last frostStart indoorsPlant out
Fargo, NDMay 10Mar 15 to 29May 3 to 17
Bismarck, NDMay 14Mar 19 to Apr 2May 7 to 21
Grand Forks, NDMay 10Mar 15 to 29May 3 to 17

How to grow lettuceAll zonesLettuce in zone 3bLettuce in zone 4bAbout zone 4a

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