When to plant sweet potato in Washington
Washington spans USDA zones 6b–9a, so the right time to plant sweet potato shifts by weeks across the state. The window to transplant seedlings outdoors runs from about March 22 in Port Townsend to June 20 in Cheney — below are local dates for 132 cities, each computed from its own frost dates.
| City | Zone | Last frost | First frost | Transplant out |
|---|---|---|---|---|
| Seattle | 9a | March 8 | November 23 | March 29 – April 12 |
| Spokane | 7a | April 26 | October 15 | May 17 – May 31 |
| Tacoma | 8b | March 8 | November 14 | March 29 – April 12 |
| Vancouver | 8b | March 29 | November 9 | April 19 – May 3 |
| Bellevue | 9a | March 8 | November 23 | March 29 – April 12 |
| Kent | 8b | March 20 | November 10 | April 10 – April 24 |
| Everett | 8b | March 24 | November 2 | April 14 – April 28 |
| Spokane Valley | 7a | April 26 | October 15 | May 17 – May 31 |
Sweet Potato in Washington: FAQ
When can I plant sweet potato in Washington?
Across Washington, the time to transplant sweet potato spans roughly March 22 in Port Townsend to June 20 in Cheney, each following that city's local frost dates.
Does the sweet potato planting date vary across Washington?
Yes. Washington publishes 132 cities with their own frost dates, so the right sweet potato 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 sweet potato take to grow in Washington?
Sweet Potato takes about 90–120 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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