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When to plant sunflowers in zone 3a

In zone 3a, where the last spring frost typically comes around May 26, sow outdoors May 26 to June 16.

The zone 3a schedule for sunflowers

Sow outdoors
May 26 to June 16
Safest planting date (10% frost risk)
June 11
First harvest, roughly
July 15 to September 14

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 sunflowers.

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

Sunflowers are killed by frost, so if you want to be safe, plant out after the safe date rather than the typical one, or be ready to cover plants on a cold night.

Your dates for sunflowers

Set your ZIP code at the top of the page and we will work out when to plant sunflowers 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 sunflowersAll zonesSunflowers in zone 2aSunflowers in zone 3bAbout zone 3a

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