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When to plant onions in zone 2a

In zone 2a, where the last spring frost typically comes around May 19, start onions indoors January 27 to March 10 and plant out April 21 to May 5.

The zone 2a schedule for onions

Start seeds indoors
January 27 to March 10
Plant out
April 21 to May 5
Sow outdoors
April 7 to 21

From the median frost dates of the NOAA stations assigned to the 10 ZIP codes in zone 2a, 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 2a

Zones are based on winter cold, not on frost dates, so the last spring frost varies a lot within a zone. Across zone 2a, the typical last frost ranges from about May 13 in the earliest tenth of ZIP codes to May 25 in the latest tenth, and the first fall frost from September 1 to September 13. For a typical place in the zone:

  • May 8Risky: a later frost happens in 9 years out of 10
  • May 19Typical: frost after this date in half of years
  • June 1Safe: 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 3aAbout zone 2a

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