When to plant sunflower in Wyoming
Wyoming spans USDA zones 4a–5b, so the right time to plant sunflower shifts by weeks across the state. The window to sow seed directly outdoors runs from about May 10 in Casper to June 20 in Jackson — below are local dates for 11 cities, each computed from its own frost dates.
| City | Zone | Last frost | First frost | Direct sow |
|---|---|---|---|---|
| Cheyenne | 5b | May 14 | October 1 | May 14 – June 4 |
| Casper | 5a | May 10 | September 29 | May 10 – May 31 |
| Gillette | 4b | May 15 | October 1 | May 15 – June 5 |
| Laramie | 4a | June 7 | September 4 | June 7 – June 28 |
| Rock Springs | 5a | May 24 | September 24 | May 24 – June 14 |
| Sheridan | 5a | May 21 | September 23 | May 21 – June 11 |
| Evanston | 5a | June 12 | September 12 | June 12 – July 3 |
| Green River | 5a | May 24 | September 22 | May 24 – June 14 |
Sunflower in Wyoming: FAQ
When can I plant sunflower in Wyoming?
Across Wyoming, the time to direct-sow sunflower spans roughly May 10 in Casper to June 20 in Jackson, each following that city's local frost dates.
Does the sunflower planting date vary across Wyoming?
Yes. Wyoming publishes 11 cities with their own frost dates, so the right sunflower planting window shifts by weeks between the warmest and coldest parts of the state — use your city's page for the exact dates.
How long does sunflower take to grow in Wyoming?
Sunflower takes about 70–100 days to reach harvest once planted — check that this fits inside your city's frost-free season on its place page.
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