When Is the Last Frost in New Hampshire?
The average last spring frost in New Hampshire falls between April 30 and May 19 for most ZIP codes, with a statewide median of May 7. At the average date a later frost is still a coin flip, so tender plants wait for the safer 90% date.
| City | Last frost | 90% safe after | First frost | Growing season |
|---|---|---|---|---|
| Manchester | Apr 30 | May 14 | Oct 11 | 164 days |
| Nashua | Apr 29 | May 11 | Oct 8 | 162 days |
| Concord | May 8 | May 22 | Oct 3 | 146 days |
| Dover | May 3 | May 16 | Oct 10 | 158 days |
| Rochester | Apr 30 | May 13 | Oct 9 | 161 days |
| Keene | May 14 | May 28 | Oct 1 | 138 days |
| Portsmouth | May 4 | May 18 | Oct 8 | 157 days |
| Laconia | Apr 30 | May 13 | Oct 18 | 170 days |
| Lebanon | May 9 | May 24 | Oct 6 | 148 days |
| Claremont | May 14 | May 29 | Oct 1 | 140 days |
| Berlin | May 14 | May 30 | Sep 30 | 135 days |
Last and first frost: 50% (median) dates of the last spring and first fall 32 °F night. 90% safe after: only a 10% chance of a later spring frost. First frost dates in January fall in the following winter. Each city uses the NOAA station nearest the ZIP code closest to its center.
Across all 54 New Hampshire weather stations with frost records, median last frost dates run from April 21 at Manchester AP, NH to May 31 at Colebrook 3 SW, NH. Elevation, valleys that collect cold air and distance from large water bodies explain most of the spread, so a garden a few miles from a listed city can differ by a week or more. The ZIP code lookup above uses the same NOAA data as the frost date calculator for every US ZIP code.
When Is the First Frost in New Hampshire?
The average first fall frost in New Hampshire arrives between September 26 and October 12 for most ZIP codes, with a median of October 4. Tomatoes, peppers, basil and squash are damaged at 32 °F, so harvest or cover them before then.
Fall frost can come early: Manchester has a 10% chance of frost before September 30, Nashua has a 10% chance of frost before September 28 and Concord has a 10% chance of frost before September 21. Hardy crops such as kale, spinach and cabbage tolerate light frosts and keep producing after the first frost date.
When to Plant Tomatoes in New Hampshire?
Transplant tomatoes in New Hampshire 1 to 2 weeks after the local average last frost, once nights stay above about 50 °F: May 7 – May 14 in Manchester, May 6 – May 13 in Nashua and May 15 – May 22 in Concord. Start seeds indoors 6 to 8 weeks before the last frost.
| City | Start seeds indoors | Transplant outdoors | Lowest-risk transplant |
|---|---|---|---|
| Manchester | Mar 5 – Mar 19 | May 7 – May 14 | after May 14 |
| Nashua | Mar 4 – Mar 18 | May 6 – May 13 | after May 11 |
| Concord | Mar 13 – Mar 27 | May 15 – May 22 | after May 22 |
| Dover | Mar 8 – Mar 22 | May 10 – May 17 | after May 16 |
| Rochester | Mar 5 – Mar 19 | May 7 – May 14 | after May 13 |
| Keene | Mar 19 – Apr 2 | May 21 – May 28 | after May 28 |
| Portsmouth | Mar 9 – Mar 23 | May 11 – May 18 | after May 18 |
| Laconia | Mar 5 – Mar 19 | May 7 – May 14 | after May 13 |
| Lebanon | Mar 14 – Mar 28 | May 16 – May 23 | after May 24 |
| Claremont | Mar 19 – Apr 2 | May 21 – May 28 | after May 29 |
| Berlin | Mar 19 – Apr 2 | May 21 – May 28 | after May 30 |
Indoors: 6–8 weeks before the average last frost. Outdoors: 1–2 weeks after it. Lowest-risk: after the date with only a 10% chance of a later frost. Rules of thumb; check the 10-day forecast and wait for soil near 60 °F.
Tomatoes stall below about 50 °F at night and are killed by frost, so a week or two of waiting after the average date costs little. The tomato plant care guide covers light, watering and feeding once plants are in the ground.
What Can You Plant in Manchester and When?
Manchester's average last frost of April 30 anchors its spring planting calendar: peas and spinach go in from March 19, broccoli and lettuce transplants from April 2, and tomatoes, peppers and squash after May 7.
| Crop | Start seeds indoors | Plant outdoors | Frost tolerance |
|---|---|---|---|
| Peas | — | Mar 19 – Apr 2direct sow, 4–6 weeks before last frost | hardy |
| Spinach | — | Mar 19 – Apr 9direct sow, 3–6 weeks before last frost | hardy |
| Radishes | — | Mar 26 – Apr 9direct sow, 3–5 weeks before last frost | hardy |
| Onions (sets) | — | Apr 2 – Apr 16plant, 2–4 weeks before last frost | hardy |
| Potatoes | — | Apr 2 – Apr 16plant, 2–4 weeks before last frost | half-hardy |
| Broccoli & cabbage | Mar 5 – Mar 19 | Apr 2 – Apr 16transplant, 2–4 weeks before last frost | hardy |
| Lettuce | Mar 19 – Apr 2 | Apr 2 – Apr 16transplant, 2–4 weeks before last frost | hardy |
| Beets | — | Apr 2 – Apr 16direct sow, 2–4 weeks before last frost | half-hardy |
| Carrots | — | Apr 9 – Apr 16direct sow, 2–3 weeks before last frost | half-hardy |
| Tomatoes | Mar 5 – Mar 19 | May 7 – May 14transplant, 1–2 weeks after last frost | tender |
| Basil | Mar 5 – Mar 19 | May 7 – May 21transplant, 1–3 weeks after last frost | tender |
| Peppers | Feb 19 – Mar 5 | May 14 – May 21transplant, 2–3 weeks after last frost | tender |
| Eggplant | Feb 19 – Mar 5 | May 14 – May 21transplant, 2–3 weeks after last frost | tender |
| Green beans | — | May 7 – May 21direct sow, 1–3 weeks after last frost | tender |
| Sweet corn | — | May 7 – May 21direct sow, 1–3 weeks after last frost | tender |
| Cucumbers | Apr 2 – Apr 9 | May 7 – May 21transplant, 1–3 weeks after last frost | tender |
| Squash & zucchini | Apr 2 – Apr 9 | May 7 – May 21transplant, 1–3 weeks after last frost | tender |
| Watermelon | Apr 2 – Apr 9 | May 14 – May 21transplant, 2–3 weeks after last frost | tender |
Dates for Manchester (last frost Apr 30, NOAA station Massabesic Lake, NH, 4 miles from ZIP 03101). General rules of thumb; wait for soil near 50 °F for most seeds and 60 °F for beans, corn and squash.
How Long Is the Growing Season in New Hampshire?
The frost-free growing season in New Hampshire lasts about 129 to 164 days for most ZIP codes, with a median of 148 days. Among the listed cities, Berlin has the shortest season at 135 days and Laconia the longest at 170.
Season length decides which varieties ripen: compare it with the “days to maturity” on seed packets, counted from transplanting for tomatoes and peppers. NOAA stations in New Hampshire range from 112 days at Colebrook 3 SW, NH to 180 days at Manchester AP, NH. Planning beds before the season starts helps in short seasons — a plant spacing calculator for vegetable beds shows how many transplants fit.
What Hardiness Zones Are in New Hampshire?
New Hampshire spans USDA hardiness zones 4a to 6b, with zone 6a the most common. Zones describe winter cold and decide which perennials survive, while frost dates set when to plant annual vegetables and flowers.
The New Hampshire planting zone map with the zone of each city shows how the zones are spread across the state and which plants are hardy in all of them.
Frequently Asked Questions
- When is the last frost in New Hampshire?
- The average last spring frost in New Hampshire falls between April 30 and May 19 for most ZIP codes, with a statewide median of May 7. Among major cities it ranges from April 29 in Nashua to May 14 in Berlin.
- When is the last frost in Manchester, New Hampshire?
- Manchester's average last spring frost is April 30, and by May 14 the chance of a later frost drops to 10%. Its first fall frost averages October 11, giving a 164-day growing season (NOAA station Massabesic Lake, NH).
- When should you plant tomatoes in New Hampshire?
- Transplant tomatoes in New Hampshire 1 to 2 weeks after the local average last frost, once nights stay above about 50 °F: May 7 – May 14 in Manchester, May 6 – May 13 in Nashua and May 15 – May 22 in Concord. Start seeds indoors 6 to 8 weeks before the last frost.
- When is the first frost in New Hampshire?
- The average first fall frost in New Hampshire arrives between September 26 and October 12 for most ZIP codes, with a median of October 4. Harvest tender crops such as tomatoes, peppers and basil before then or cover them on cold nights.
- How long is the growing season in New Hampshire?
- The frost-free growing season in New Hampshire lasts about 129 to 164 days for most ZIP codes, with a median of 148 days, from 135 days in Berlin to 170 days in Laconia.
Frost data: NOAA National Centers for Environmental Information, 1991–2020 U.S. Climate Normals (32 °F freeze dates by probability). ZIP code and city locations and populations: U.S. Census Bureau Gazetteer files and Vintage 2024 population estimates. Planting windows are general rules of thumb. PlantoScan is not affiliated with or endorsed by these agencies.