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Maine frost dates
Across the 13Maine weather stations below, the average last spring frost ranges from Apr 26 in Portland Jetport to May 27 in Houlton. The statewide middle is about May 7 for the last spring frost and Oct 2 for the first fall frost. Portland Jetport has the longest growing season, about 172 days. Hardiness zones in these places: 4a, 4b, 5a, 5b, 6a.
Frost dates by city
| Place | Zone | Last spring frost | 90% safe after | First fall frost | Frost-free days |
|---|---|---|---|---|---|
| Portland Jetport | 6a | Apr 26 | May 7 | Oct 15 | 172 |
| Augusta | 5b | Apr 27 | May 7 | Oct 16 | 172 |
| Brunswick | 5b | May 2 | May 14 | Oct 10 | 161 |
| Bangor | 5a | May 4 | May 17 | Oct 4 | 153 |
| Frenchville Aroostook | 4b | May 6 | May 21 | Oct 2 | 149 |
| Caribou | 4a | May 7 | May 24 | Oct 1 | 147 |
| Greenville Maine Forestry Svc | 4b | May 7 | May 20 | Oct 9 | 155 |
| Millinocket | 5a | May 8 | May 24 | Oct 1 | 146 |
| Wiscasset | 5b | May 8 | May 20 | Oct 7 | 152 |
| Old Town 2 W | 5a | May 13 | May 28 | Sep 28 | 138 |
| Limestone 4 Nnw | 4a | May 16 | Jun 1 | Sep 24 | 131 |
| Fryeburg E Slopes | 5a | May 17 | Jun 1 | Sep 25 | 131 |
| Houlton | 4b | May 27 | Jun 10 | Sep 18 | 114 |
Dates are the 50% probability of a 32°F freeze (NOAA 1991–2020 normals); "90% safe after" is the date after which a later spring freeze happens in only 1 year in 10.
When to plant in Maine
Using the statewide middle dates (last frost May 7, first frost Oct 2). Adjust for your town with the table above or the planting calendar.
| Plant | When to plant in Maine |
|---|---|
| Tomatoes | May 14 – May 28 |
| Peas | Mar 26 – Apr 16; fall: Jul 10 – Jul 31 |
| Potatoes | Apr 9 – Apr 30 |
| Green beans | May 14 – May 28; fall: Jul 17 – Jul 31 |
| Garlic | Oct 2 – Oct 30 |
| Tulips | Sep 18 – Oct 30 |