USDA hardiness zones in New Hampshire
| Zone | Avg. extreme minimum | ZIP codes | Example cities |
|---|---|---|---|
| Zone 4a | −30 to −25°F | 5 | — |
| Zone 4b | −25 to −20°F | 19 | Berlin |
| Zone 5a | −20 to −15°F | 82 | Lebanon |
| Zone 5b | −15 to −10°F | 75 | Concord, Keene, Laconia, Claremont |
| Zone 6a | −10 to −5°F | 91 | Manchester, Nashua, Dover, Rochester |
| Zone 6b | −5 to 0°F | 1 | — |
Growing zone and frost dates by city
| City | Zone | Frost dates |
|---|---|---|
| Manchester | 6a (−10 to −5°F) | Manchester frost dates |
| Nashua | 6a (−10 to −5°F) | Nashua frost dates |
| Concord | 5b (−15 to −10°F) | Concord frost dates |
| Dover | 6a (−10 to −5°F) | Dover frost dates |
| Rochester | 6a (−10 to −5°F) | Rochester frost dates |
| Keene | 5b (−15 to −10°F) | Keene frost dates |
| Portsmouth | 6a (−10 to −5°F) | Portsmouth frost dates |
| Laconia | 5b (−15 to −10°F) | Laconia frost dates |
| Lebanon | 5a (−20 to −15°F) | Lebanon frost dates |
| Claremont | 5b (−15 to −10°F) | Claremont frost dates |
| Somersworth | 6a (−10 to −5°F) | Somersworth frost dates |
| Berlin | 4b (−25 to −20°F) | Berlin frost dates |
| Franklin | 5b (−15 to −10°F) | Franklin frost dates |
Frequently asked questions
What growing zone is New Hampshire in?
New Hampshire’s ZIP codes span USDA zones 4a to 6b, and 6a is the most common. Zones vary with elevation and distance from water, so check your own ZIP code.
When should I plant?
Hardiness zones are about winter cold, not planting dates. For timing, use the last spring frost date for your city on our New Hampshire frost dates page.