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When to plant sunflowers in zone 3b

In zone 3b, where the last spring frost typically comes around May 17, sow outdoors May 17 to June 7.

The zone 3b schedule for sunflowers

Sow outdoors
May 17 to June 7
Safest planting date (10% frost risk)
May 30
First harvest, roughly
July 6 to September 5

From the median frost dates of the NOAA stations assigned to the 200 ZIP codes in zone 3b, and the timing recommended by Cooperative Extension guides for sunflowers.

Frost risk in zone 3b

Zones are based on winter cold, not on frost dates, so the last spring frost varies a lot within a zone. Across zone 3b, the typical last frost ranges from about May 12 in the earliest tenth of ZIP codes to May 29 in the latest tenth, and the first fall frost from September 13 to October 1. For a typical place in the zone:

  • May 4Risky: a later frost happens in 9 years out of 10
  • May 17Typical: frost after this date in half of years
  • May 30Safe: 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 3aSunflowers in zone 4aAbout zone 3b

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