When to plant sunflower in Idaho
Idaho spans USDA zones 5a–7a, so the right time to plant sunflower shifts by weeks across the state. The window to sow seed directly outdoors runs from about April 6 in Lewiston to May 17 in Garden City — below are local dates for 25 cities, each computed from its own frost dates.
| City | Zone | Last frost | First frost | Direct sow |
|---|---|---|---|---|
| Boise City | 7a | April 24 | October 21 | April 24 – May 15 |
| Meridian | 7a | April 24 | October 21 | April 24 – May 15 |
| Nampa | 7a | April 29 | October 13 | April 29 – May 20 |
| Idaho Falls | 5b | May 9 | October 1 | May 9 – May 30 |
| Caldwell | 7a | April 29 | October 13 | April 29 – May 20 |
| Pocatello | 6a | May 2 | October 11 | May 2 – May 23 |
| Coeur d'Alene | 6b | April 22 | October 18 | April 22 – May 13 |
| Twin Falls | 7a | April 30 | October 9 | April 30 – May 21 |
Sunflower in Idaho: FAQ
When can I plant sunflower in Idaho?
Across Idaho, the time to direct-sow sunflower spans roughly April 6 in Lewiston to May 17 in Garden City, each following that city's local frost dates.
Does the sunflower planting date vary across Idaho?
Yes. Idaho publishes 25 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 Idaho?
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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