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New Hampshire frost dates
Across the 9New Hampshire weather stations below, the average last spring frost ranges from Apr 21 in Manchester to May 30 in Berlin. The statewide middle is about May 7 for the last spring frost and Oct 6 for the first fall frost. Manchester has the longest growing season, about 181 days. Hardiness zones in these places: 4b, 5a, 5b, 6a.
Frost dates by city
| Place | Zone | Last spring frost | 90% safe after | First fall frost | Frost-free days |
|---|---|---|---|---|---|
| Manchester | 6a | Apr 21 | May 6 | Oct 19 | 181 |
| Rochester Skyhaven | 6a | Apr 30 | May 13 | Oct 9 | 162 |
| Durham 2 N | 6a | May 3 | May 16 | Oct 10 | 160 |
| Jaffrey | 6a | May 5 | May 20 | Oct 6 | 154 |
| Durham 2 Ssw | 6a | May 7 | May 19 | Oct 4 | 150 |
| Concord | 5b | May 8 | May 22 | Oct 3 | 148 |
| Lebanon | 5a | May 9 | May 24 | Oct 6 | 150 |
| Whitefield Mt Washington | 4b | May 27 | Jun 10 | Sep 19 | 115 |
| Berlin | 4b | May 30 | Jun 11 | Sep 19 | 112 |
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 New Hampshire
Using the statewide middle dates (last frost May 7, first frost Oct 6). Adjust for your town with the table above or the planting calendar.
| Plant | When to plant in New Hampshire |
|---|---|
| Tomatoes | May 14 – May 28 |
| Peas | Mar 26 – Apr 16; fall: Jul 14 – Aug 4 |
| Potatoes | Apr 9 – Apr 30 |
| Green beans | May 14 – May 28; fall: Jul 21 – Aug 4 |
| Garlic | Oct 6 – Nov 3 |
| Tulips | Sep 22 – Nov 3 |