New Hampshire planting zones range from 3b to 6b, with most of the state falling within zones 5a, 5b, and 6a. Let’s explore each of these zones so you can create a thriving garden in the Granite State.
But if you want to know the planting zone of your specific area, below you can find links to our guides for each New Hampshire region:
- Planting Zones of Southern New Hampshire
- Planting Zones of Central New Hampshire
- Planting Zones of Northern New Hampshire
What planting zone is New Hampshire?
In the new USDA hardiness planting zone map, New Hampshire planting zones range from 3b to 6b, with the average annual extreme minimum temperature ranging from -35 F to 0 F. That means that temperatures can vary in New Hampshire, and one plant that is adapted to one part of the state might not be to another.
Most of New Hampshire falls within zones 5a, 5b, and 6a, which experience minimum temperatures ranging from -20 F to -5 F. Let’s take a look at the NH zone map and each of the planting zones:
Zone 3b
The only region of New Hampshire that falls into zone 3b is the Mount Washington State Park area. This area experiences average minimum temperatures of -35 F to -30 F in high elevations.
In this harsh climate, the growing season is short, and the high altitude further hinders plant growth. The soil does not retain moisture well, so plants are mostly tiny and grow close to the ground.
Zone 4a
Most of the northern part of New Hampshire is located in zone 4a, which experiences average minimum temperatures ranging from -30 F to -25 F. This area covers the upper half of Coos County, with part of Lancaster, the county seat, situated within this zone. Some areas around Mount Washington State Park are also in this zone.
The cold temperatures and challenging climate in zone 4a require selecting hardy plants that can endure severe winters and shorter growing seasons. You can check out our article to learn how to use hardiness zones to choose plants for your yard.
Zone 4b
Other parts of Coos County, as well as the northernmost part of Grafton County, are in zone 4b. This zone experiences average minimum temperatures of -25 F to -20 F. Important regions within this zone include:
- The city of Berlin, in Coos County
- Littleton, in Grafton County
- Some areas of the White Mountains National Forest
Zone 5a
Around one-third of New Hampshire falls into zone 5a, primarily in central New Hampshire. This USDA hardiness zone experiences average minimum temperatures of -20 F to -15 F. It encompasses the following areas:
- Most of Grafton County, including the city of Lebanon and the towns of Haverhill and Hanover.
- Most of Carroll County, including the towns of Conway and Ossipee
- Some regions in the northernmost part of Sullivan County, including the county seat, Newport.
- A small region in Merrimack County, located near the border with Sullivan and Grafton counties, where the town of Danbury is situated.
Zone 5b
Several regions of central and southern New Hampshire fall into zone 5b, experiencing average minimum temperatures of -15 F to -10 F. The following areas of New Hampshire are in this zone:
- Grafton County: Near the Pemigewasset River and Newfound Lake
- Carroll County: Southern region, including Wolfeboro
- Belknap County: The majority of this county is located within zone 5b
- Merrimack County: The majority of the county, including the state capital, Concord
- Sullivan County: Some regions, including its largest city, Claremont
- Strafford County: Northern part of the county
- Cheshire County: Some regions, including the area where Keene is located
- Hillsborough County: Some western regions of the county, including Peterborough
Pro tip: Zone 5b offers a slightly milder climate than the previous zone, which means you’ll be able to grow a beautiful lawn in these regions. Check out our guide, The Best Grass Seed for New Hampshire Lawns, for more information.
Zone 6a
Southern New Hampshire is primarily located within zone 6a, with only a few exceptions of counties that have areas in zone 5b and 6b. Zone 6a experiences minimum average temperatures of -10 to -5 F.
Here are the New Hampshire counties that have areas in zone 6a:
- Belknap County: A small region that includes the city of Laconia, near Lake Winnisquam
- Sullivan County: The lower half is mainly in zone 6a
- Merrimack County: Some regions in the southern and western parts of the county
- Stafford County: Nearly two-thirds of the county is in zone 6a, including the city of Dover
- Cheshire County: Has at least half of the county’s area in this zone
- Hillsborough County: The majority of the county, including important cities like Nashua and Manchester
- Rockingham County: Almost the entire county, except for a small region near the coast. It includes the cities of Portsmouth and Brentwood.
Tip: You’ll be able to plant grass seeds a bit later in this area (as late as early October). To learn more about planting dates, check out our guide: When to Plant Grass Seed in New Hampshire.
Zone 6b
The only area in New Hampshire located in zone 6b is a small region on the coast in Rockingham County. This zone includes the Hampton Beach State Park, the town of Seabrook, Hampton, and surrounding areas.
Zone 6b experiences average minimum temperatures ranging from -5 F to 0 F, providing the mildest winter conditions in the state.
When to call a pro
If you’re still not sure which planting zone your city or town is located in, we recommend typing your ZIP code into the USDA hardiness zone map for precise information.
But if you’re looking for personalized advice on which plants to include in your landscape and how to plant them, consider calling a lawn care pro in your area. They have the expertise to help you create a thriving garden, tailored to New Hampshire’s climate, while you enjoy some well-deserved cider doughnuts.
Main Image Credit: Doug Kerr | Flickr | CC BY-SA 2.0
