Dover, NH planting zone & frost dates
Dover is in USDA hardiness zone 6a. The last spring frost usually comes around May 3 and the first fall frost around October 10, for a growing season of about 158 days.
Planting calendar for Dover
Dates are counted from the average last spring frost (May 3) using the typical timing recommended by U.S. extension services. Warm-season crops go out only after the danger of frost has passed and the soil has warmed.
| Crop | When |
|---|---|
| Tomatoes | Start seeds indoors: Mar 8 – Mar 22 Transplant outdoors: May 10 – May 17 |
| Peppers | Start seeds indoors: Feb 22 – Mar 8 Transplant outdoors: May 17 – May 24 |
| Eggplant | Start seeds indoors: Feb 22 – Mar 8 Transplant outdoors: May 17 – May 24 |
| Broccoli | Start seeds indoors: Feb 22 – Mar 8 Transplant outdoors: Apr 5 – Apr 19 |
| Cabbage | Start seeds indoors: Feb 22 – Mar 8 Transplant outdoors: Apr 5 – Apr 19 |
| Onions (sets) | Plant outdoors: Apr 5 – Apr 19 |
| Peas | Sow outdoors: Mar 22 – Apr 5 |
| Spinach | Sow outdoors: Mar 22 – Apr 5 |
| Lettuce | Sow outdoors: Apr 5 – Apr 19 |
| Carrots | Sow outdoors: Apr 5 – Apr 19 |
| Potatoes | Plant outdoors: Apr 5 – Apr 19 |
| Beans | Sow outdoors: May 10 – May 17 |
| Sweet corn | Sow outdoors: May 10 – May 17 |
| Cucumbers | Sow outdoors: May 10 – May 17 |
| Squash & zucchini | Sow outdoors: May 10 – May 17 |
| Basil | Start seeds indoors: Mar 22 – Apr 5 Transplant outdoors: May 10 – May 17 |
Fall garden: cool-season crops like lettuce, spinach and kale can be sown again around Aug 15 (8 weeks before the average first fall frost on Oct 10).
Useful for zone 6a gardens
- Seed starting kit with dome — to start seeds indoors before the last frost
- LED grow light for seedlings — stops leggy seedlings
- Frost cloth / plant covers — for late spring and early fall frosts
- Soil thermometer — warm-season crops need soil above 60°F
- Cold frame / mini greenhouse — adds weeks to a short season
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Frost risk in detail
| 90% chance | 50% chance | 10% chance | |
|---|---|---|---|
| Last 32°F frost in spring is after | Apr 23 | May 3 | May 16 |
| First 32°F frost in fall is before | Oct 25 | Oct 10 | Sep 27 |
How to read it: in spring there is a 10% chance of a frost after May 16, so that is a safe date for tender plants. In fall there is a 10% chance of frost before September 27. A hard freeze (28°F) usually ends around April 20.
Hardiness zone by ZIP code in Dover
- 03820 zone 6a
- 03821 zone 6a
- 03822 zone 6a
Nearby cities
- Somersworth zone 6a, last frost Apr 30
- Durham zone 6a, last frost May 8
- Rochester zone 6a, last frost Apr 30
- Portsmouth zone 6a, last frost May 4
- Salem zone 6a, last frost Apr 21
- Derry Village zone 6a, last frost Apr 30
- Derry zone 6a, last frost Apr 30
- Windham zone 6a, last frost May 3
Questions
What growing zone is Dover, NH?
Dover is in USDA Plant Hardiness Zone 6a (average extreme winter low -10°F to -5°F), according to the USDA 2023 map.
When is the last frost in Dover?
The average last spring frost (32°F) in Dover is May 3. There is still a 10% chance of frost until May 16.
When can I plant tomatoes in Dover?
Transplant tomatoes outdoors 1–2 weeks after the average last frost: around May 10 – May 17. Start seeds indoors 6–8 weeks before the last frost.
Frost dates: NOAA U.S. Climate Normals 1991–2020, station Durham 2 N, NH (USW00054794), 5.3 km (3.3 mi) from the city center, elevation 36 m, based on 19 years of records. Hardiness zone: USDA Plant Hardiness Zone Map 2023 for the ZIP code nearest to the city center. Microclimates (valleys, hills, cities, coasts) can be warmer or colder: check the local forecast before planting. How we calculate the data.