When to plant sunflower in South Dakota
South Dakota 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 April 26 in Sioux Falls to May 12 in Spearfish — below are local dates for 13 cities, each computed from its own frost dates.
| City | Zone | Last frost | First frost | Direct sow |
|---|---|---|---|---|
| Sioux Falls | 5a | April 26 | October 13 | April 26 – May 17 |
| Rapid City | 5b | May 3 | October 8 | May 3 – May 24 |
| Aberdeen | 4a | May 8 | September 29 | May 8 – May 29 |
| Brookings | 4b | May 6 | October 1 | May 6 – May 27 |
| Watertown | 4b | May 7 | September 30 | May 7 – May 28 |
| Mitchell | 5a | May 2 | October 6 | May 2 – May 23 |
| Yankton | 5a | April 27 | October 11 | April 27 – May 18 |
| Huron | 4b | May 6 | October 2 | May 6 – May 27 |
Sunflower in South Dakota: FAQ
When can I plant sunflower in South Dakota?
Across South Dakota, the time to direct-sow sunflower spans roughly April 26 in Sioux Falls to May 12 in Spearfish, each following that city's local frost dates.
Does the sunflower planting date vary across South Dakota?
Yes. South Dakota publishes 13 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 South Dakota?
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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