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When to plant onions in zone 3a

In zone 3a, where the last spring frost typically comes around May 26, start onions indoors February 3 to March 17 and plant out April 28 to May 12.

The zone 3a schedule for onions

Start seeds indoors
February 3 to March 17
Plant out
April 28 to May 12
Sow outdoors
April 14 to 28

From the median frost dates of the NOAA stations assigned to the 8 ZIP codes in zone 3a, and the timing recommended by Cooperative Extension guides for onions.

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 3a

Zones are based on winter cold, not on frost dates, so the last spring frost varies a lot within a zone. Across zone 3a, the typical last frost ranges from about May 10 in the earliest tenth of ZIP codes to June 2 in the latest tenth, and the first fall frost from September 12 to October 1. For a typical place in the zone:

  • May 10Risky: a later frost happens in 9 years out of 10
  • May 26Typical: frost after this date in half of years
  • June 11Safe: a later frost only 1 year in 10

Your dates for onions

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

How to grow onionsAll zonesOnions in zone 2aOnions in zone 3bAbout zone 3a

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