When to plant sweet potato in Montana
Montana spans USDA zones 4b–5b, so the right time to plant sweet potato shifts by weeks across the state. The window to transplant seedlings outdoors runs from about May 25 in Billings to July 4 in Butte-Silver Bow — below are local dates for 8 cities, each computed from its own frost dates.
| City | Zone | Last frost | First frost | Transplant out |
|---|---|---|---|---|
| Billings | 5a | May 4 | October 7 | May 25 – June 8 |
| Missoula | 5b | May 10 | October 1 | May 31 – June 14 |
| Great Falls | 4b | May 6 | October 1 | May 27 – June 10 |
| Bozeman | 5a | May 26 | September 22 | June 16 – June 30 |
| Butte-Silver Bow | 5a | June 13 | September 5 | July 4 – July 18 |
| Helena | 5a | May 9 | September 30 | May 30 – June 13 |
| Kalispell | 5b | May 31 | September 10 | June 21 – July 5 |
| Belgrade | 5a | May 26 | September 16 | June 16 – June 30 |
Sweet Potato in Montana: FAQ
When can I plant sweet potato in Montana?
Across Montana, the time to transplant sweet potato spans roughly May 25 in Billings to July 4 in Butte-Silver Bow, each following that city's local frost dates.
Does the sweet potato planting date vary across Montana?
Yes. Montana publishes 8 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 Montana?
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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