Nashua, New Hampshire: planting zone & frost dates
Nashua is in USDA plant hardiness zone 6a, where the average coldest winter night reaches -10 to -5°F (-23.3 to -20.6°C). The typical last spring frost is around May 4 and the first fall frost around Oct 5.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | May 11 | Sep 30 |
| Typical planning date (30% risk) | May 4 | Oct 5 |
| Median (50%) | Apr 30 | Oct 12 |
How to read this: after the spring "10% risk" date, a 32°F frost happens in only about 1 year in 10. In fall, the "10% risk" date is the early end — a frost before it happens about 1 year in 10.
Frost data comes from NOAA station NASHUA 2 NNW, NH (USC00275712), 3.0 mi (4.9 km) from the city center and 56 ft lower than the city center (-17 m). Record used for the 1991–2020 normals: 26 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across Nashua
All 4 ZIP codes covering Nashua are in zone 6a.
Vegetable planting calendar for Nashua
Dates are counted from the 30%-risk frost dates above (last frost May 4, first frost Oct 5). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Mar 9 – Mar 23 | May 11 – May 25 | — | — |
| Pepper | Feb 23 – Mar 9 | May 18 – Jun 1 | — | — |
| Lettuce | Mar 23 – Apr 6 | Apr 20 – May 11 | Apr 6 – May 18 | Jul 27 – Aug 24 |
| Green Beans | — | — | May 11 – Jun 15 | Jul 13 – Jul 27 |
| Sweet Corn | — | — | May 11 – Jun 8 | — |
| Zucchini & Summer Squash | Apr 6 – Apr 13 | May 11 – May 25 | May 11 – Jun 1 | Jul 13 – Jul 27 |
| Cucumber | Apr 6 – Apr 13 | May 18 – May 25 | May 11 – Jun 1 | Jul 13 – Jul 27 |
| Carrot | — | — | Apr 13 – May 18 | Jul 13 – Jul 27 |
| Onion | Feb 9 – Feb 23 | Apr 6 – Apr 20 | — | — |
| Potato | — | Apr 6 – Apr 27 | — | — |
| Basil | Mar 23 – Apr 6 | May 18 – Jun 1 | May 18 – Jun 8 | — |
| Spinach | — | — | Mar 23 – Apr 20 | Aug 10 – Sep 7 |
| Kale | Mar 9 – Mar 23 | Apr 6 – Apr 27 | Apr 6 – Apr 27 | Jul 27 – Aug 24 |
| Broccoli | Mar 9 – Mar 23 | Apr 20 – May 11 | — | Jul 13 – Jul 27 |
| Peas | — | — | Mar 23 – Apr 13 | Jul 27 – Aug 10 |
| Eggplant | Feb 23 – Mar 9 | May 18 – Jun 1 | — | — |
| Cabbage | Mar 9 – Mar 23 | Apr 6 – Apr 20 | — | Jul 13 – Jul 27 |
| Radish | — | — | Mar 30 – May 18 | Aug 24 – Sep 21 |
| Strawberry | — | Apr 6 – Apr 27 | — | — |
| Beets | — | — | Apr 13 – May 25 | Jul 27 – Aug 10 |
Nearby cities in New Hampshire
- Manchester — zone 6a, last frost May 4, first frost Oct 6
More: all New Hampshire cities · other zone 6a cities: Chicago, IL, Denver, CO, Milwaukee, WI, Colorado Springs, CO, Omaha, NE, Aurora, CO, Lincoln, NE, Fort Wayne, IN
Nashua gardening questions
When is the last frost in Nashua, NH?
Plan around May 4. At NOAA's Nashua 2 NNW, NH station, 3.0 mi from the city center, there is a 30% chance of a 32°F frost after that date. Half of springs have their last frost by Apr 30, and after May 11 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Apr 17. The last frost is fairly predictable here: only 23 days separate the 90% and 10% dates (median for cities on this site: 36 days).
When should I plant tomatoes in Nashua, NH?
Start seeds indoors Mar 9 – Mar 23 and set transplants outside May 11 – May 25, once nights stay above 50°F and the soil is near 60°F. That leaves 154 days between the 30% frost dates, enough for most varieties including 80–85-day slicers. More: tomato planting dates by zone.
How long is the growing season in Nashua?
About 165 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 148 days, and in 1 year in 10 it runs 185 days or more. In fall there is a 10% chance of frost by Sep 30 and a 30% chance by Oct 5.
When should I plant a fall garden in Nashua?
Count back from the first fall frost (Oct 5): transplant broccoli Jul 13 – Jul 27; sow kale Jul 27 – Aug 24; sow lettuce Jul 27 – Aug 24; sow radishes Aug 24 – Sep 21. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Oct 24. How the math works: succession and fall planting.
Did Nashua's hardiness zone change on the 2023 map?
Yes. Most of Nashua was zone 5b on the 2012 map and is zone 6a on the 2023 map — half a zone warmer, like about 56% of U.S. ZIP codes. The shift comes from a newer 1991–2020 averaging period plus more weather stations and better mapping; it does not mean last frost comes earlier. Why the 2023 map is warmer.
How does Nashua compare with Lowell, MA?
Nashua is zone 6a and Lowell is zone 6b. The typical last spring frost in Nashua (May 4) comes about the same time as in Lowell, MA (May 3), 11 miles away, and the first fall frost is Oct 5 versus Oct 5. The two cities use different NOAA stations.