When to plant sunflowers in zone 6a
In zone 6a, where the last spring frost typically comes around April 29, sow outdoors April 29 to May 20.
The zone 6a schedule for sunflowers
- Sow outdoors
- April 29 to May 20
- Safest planting date (10% frost risk)
- May 14
- First harvest, roughly
- June 18 to August 18
From the median frost dates of the NOAA stations assigned to the 4,514 ZIP codes in zone 6a, and the timing recommended by Cooperative Extension guides for sunflowers.
Frost risk in zone 6a
Zones are based on winter cold, not on frost dates, so the last spring frost varies a lot within a zone. Across zone 6a, the typical last frost ranges from about April 16 in the earliest tenth of ZIP codes to May 11 in the latest tenth, and the first fall frost from October 4 to October 24. For a typical place in the zone:
- April 16Risky: a later frost happens in 9 years out of 10
- April 29Typical: frost after this date in half of years
- May 14Safe: 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.
Sunflowers in zone 6a cities
| City | Typical last frost | Plant | Fall |
|---|---|---|---|
| Chicago, IL | Apr 11 | Apr 14 to May 5 | — |
| Indianapolis city, IN | Apr 15 | Apr 15 to May 6 | — |
| Denver, CO | May 4 | May 4 to 25 | — |
| Colorado Springs, CO | May 3 | May 3 to 24 | — |
| Omaha, NE | Apr 18 | Apr 18 to May 9 | — |
| Aurora, CO | May 4 | May 4 to 25 | — |
| Lincoln, NE | Apr 24 | Apr 24 to May 15 | — |
| Fort Wayne, IN | Apr 24 | Apr 24 to May 15 | — |
| Grand Rapids, MI | Apr 29 | Apr 29 to May 20 | — |
| Lakewood, CO | May 5 | May 5 to 26 | — |
| Springfield, MA | May 3 | May 3 to 24 | — |
| Joliet, IL | Apr 19 | Apr 19 to May 10 | — |
How to grow sunflowersAll zonesSunflowers in zone 5bSunflowers in zone 6bAbout zone 6a
Sources
- Dakota Gardener: Grow a bouquet in 60 days · NDSU Extension (North Dakota State University)
- Growing Sunflowers in the Home Garden (Circular 1121) · University of Georgia Cooperative Extension
- Let's Grow Sunflowers · Clemson Cooperative Extension Home & Garden Information Center
- How to sow sunflowers in successful succession · Mississippi State University Extension
- How to Grow Sunflowers (Garden Notes GN 166) · UC ANR Cooperative Extension Sacramento County Master Gardeners
- Sunflowers · UF/IFAS Extension Gardening Solutions
- Flowers to Plant in Florida: Text (month-by-month calendar for North, Central and South Florida) · UF/IFAS Extension Gardening Solutions
- Flower Planting Guide for the Low Desert (AZ1100) · University of Arizona Cooperative Extension, Maricopa County
- Sowing Annual Seeds · Penn State Extension
- May 21, 2005 Timely Tips (Bexar County gardening calendar) · Texas A&M AgriLife Extension, Bexar County