When to plant hyssop in South Dakota
South Dakota spans USDA zones 4a–5b, so the right time to plant hyssop shifts by weeks across the state. The window to transplant seedlings 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 | Transplant out |
|---|---|---|---|---|
| Sioux Falls | 5a | April 26 | October 13 | April 26 – May 10 |
| Rapid City | 5b | May 3 | October 8 | May 3 – May 17 |
| Aberdeen | 4a | May 8 | September 29 | May 8 – May 22 |
| Brookings | 4b | May 6 | October 1 | May 6 – May 20 |
| Watertown | 4b | May 7 | September 30 | May 7 – May 21 |
| Mitchell | 5a | May 2 | October 6 | May 2 – May 16 |
| Yankton | 5a | April 27 | October 11 | April 27 – May 11 |
| Huron | 4b | May 6 | October 2 | May 6 – May 20 |
Hyssop in South Dakota: FAQ
When can I plant hyssop in South Dakota?
Across South Dakota, the time to transplant hyssop spans roughly April 26 in Sioux Falls to May 12 in Spearfish, each following that city's local frost dates.
Does the hyssop planting date vary across South Dakota?
Yes. South Dakota publishes 13 cities with their own frost dates, so the right hyssop planting window shifts by weeks between the warmest and coldest parts of the state — use your city's page for the exact dates.
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