Southern New Hampshire mainly falls within USDA hardiness zone 6a, with a few exceptions. This guide will help you navigate the planting zones of this bustling region, so you can select the best plants for your garden’s success.
But if you want to know the planting zones of other regions in the Granite State, read our articles below:
What planting zone is southern New Hampshire?
Before we start, it’s important to note that defining the exact boundaries of southern New Hampshire can be tricky, as there’s no clear consensus. For the sake of this guide, we’re considering southern New Hampshire to include all areas below Concord, including Concord itself.
Most of this region falls within zone 6a, which experiences average minimum temperatures ranging from -10 F to -5 F. However, some counties in southern New Hampshire have areas that fall into zone 5b, which is slightly colder. Additionally, there’s a small coastal area in zone 6b.
Let’s take a closer look at each county and its planting zones:
Merrimack
In Merrimack County, the area south of Concord falls into either zone 6a or zone 5b. Zone 5b experiences slightly colder temperatures, with average minimum temperatures ranging from -15 F to -10 F.
For example, Concord, the state capital, is in zone 5b, while Hooksett, just a 9-mile distance from Concord, is in zone 6a. This variation in zones means that gardeners and homeowners in Merrimack County need to be mindful of their location when choosing plants.
Strafford
The entire lower half of Strafford County falls within zone 6a. This includes cities like Dover and Rochester, which benefit from the milder winter temperatures of this zone (minimum of -10 F to -5 F).
This makes it easier to maintain a vibrant and diverse garden, as well as a lush lawn. Check out our guide, The Best Grass Seed for New Hampshire Lawns, for more information.
Cheshire
In Cheshire County, around half of the area falls within zone 6a, while the other half is in zone 5b. There aren’t clear “borders” between these zones, but generally, zone 5b covers the western, central, and southeastern parts of the county. In contrast, zone 6a includes the northeastern and south-central regions.
For instance, the city of Keene is located in zone 5b. If you’re unsure which zone you’re in, we recommend typing your ZIP code into the USDA hardiness zone map for more precise information.
Hillsborough
Here’s what you need to know about the planting zones in Hillsborough County:
- Only some western regions fall within zone 5b, primarily the area near US Route 202.
- Peterborough is in zone 5b.
- The rest of the county is in zone 6a.
- Important cities like Manchester and Nashua are in zone 6a.
You can check out the guide, When to Plant Grass Seed in New Hampshire, to learn more about what grass grows in this area and when you should plant it.
Rockingham
Almost the entire Rockingham County is located in zone 6a, including the following cities:
- Salem
- Londonderry
- Portsmouth
- Windham
However, there is a small exception: a coastal region that includes Hampton Beach State Park, the town of Seabrook, Hampton, and the surrounding area. This small area falls within zone 6b, which experiences average minimum temperatures that range from -5 to 0 F. It is the only area in New Hampshire where zone 6b is present, and it is also the mildest winter in the state.
Note: The southern part of Sullivan County is either in zone 5b or 6a. If you’re more interested to learn about Sullivan County’s planting zones, refer to our article “Planting Zones of Central New Hampshire,” linked in the beginning.
When to call a professional
Now you know everything about the planting zones in southern New Hampshire. But if you’re still confused about what planting zones are and how to use them to choose the best plants for your area, read our guide: How to Use the Plant Hardiness Zone Map in Your Yard.
For personalized assistance, you can also call a lawn care professional near you to help you select and plant the best varieties for your garden.
Main Image Credit: Joseph Greeley II House | Jane023 | Wikimedia Commons | CC BY-SA 4.0
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