The New Hampshire Seacoast spans USDA hardiness zone 6a — a zone band wide enough that plant choice, not possibility, is the interesting question.
New Hampshire's Seacoast — Rockingham and Strafford counties — sits in USDA zone 6a and posts the state's two longest frost-free seasons, about 187 to 188 days, roughly two weeks more than the Concord-area interior (Merrimack County, 173 days). The conditions favor potato, apple, sugar maple, and blueberry, among others — though every individual site edits that list with its own soil, sun, and drainage.
The New Hampshire Seacoast spans New Hampshire.
Your yard isn't all of the New Hampshire Seacoast.
The New Hampshire Seacoast spans USDA zones 6a, but your parcel sits in exactly one — and slope, tree cover, and low spots nudge it further. Enter your address and we'll score 1,086 plants against your land's actual soil, sun, and frost.
We read public map data around New Hampshire Seacoast — soil, climate, flood, and parcel records. How we handle your address.
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The New Hampshire Seacoast — the short answer
The New Hampshire Seacoast: USDA zones 6a, 187–188 frost-free days, in New Hampshire.
- USDA zones
- 6a
- USDA PHZM 2023, aggregated over the footprint
- Frost-free season
- 187–188 days
- NOAA Regional Climate Centers ACIS, 1991-2020
- Counties
- 2
- US Census TIGER/Line 2025
- Region type
- County cluster
- Growable Ground growing-region registry
Region boundary: Growable Ground growing-region registry — curated county clusters, EPA Level III ecoregions, and town clusters drawn finer than any county. Where a region publishes no measured season, no season figure is shown.
Hardiness Zone Range
What Grows in the New Hampshire Seacoast
Plants matched to the New Hampshire Seacoast's USDA zones 6a, ordered by how much hardiness margin each has across the region — the ones with room to spare at both ends of this band lead. Each links to its full growing profile.
Native Plants of the New Hampshire Seacoast
Plants the USDA PLANTS Database documents as native and present in this region’s state, kept only where the published hardiness range meets the New Hampshire Seacoast’s USDA zones 6a — closest range match first. Presence is recorded by state, so a plant can be documented across the state and still be scarce in your corner of the region.
The ground across the New Hampshire Seacoast
The USDA soil survey maps this ground county by county. These are those records weighted by land area across two member counties — this region’s own profile, not a state figure.
The ground is predominantly Inceptisols, at 73% of mapped acres, followed by Entisols (15%), Histosols (8%) and Spodosols (4%). The most extensive named soils are Canton, Hollis, and Gloucester.
44% of those acres are well drained, and another 12% poorly drained, 12% moderately well drained. Topsoil pH runs 4.3–5.5 between the lowest and the highest county on record. 7% of the footprint is classed prime farmland.
Soil order
Inceptisols
Drainage
Well drained
Topsoil pH
4.3–5.5
Hydric soils
23%
Soil changes across a driveway, so which of these your own ground sits on is a parcel question rather than a regional one. Rockingham County holds the most wetland ground here, at 25% — soil types explained.
USDA NRCS SSURGO via Soil Data Access
What this means for growing in the New Hampshire Seacoast
The soil survey reads this ground county by county, and the readings above are those records summed across the New Hampshire Seacoast. Here is what they mean for a garden here — and the move an experienced grower makes about each one.
Drainage
From county records44% of the mapped acres across the New Hampshire Seacoast are well drained — ground that drains quickly. That is area-weighted across all two of its mapped counties.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
From county recordsTopsoil across the New Hampshire Seacoast runs pH 4.3–5.5 — acidic in all two of them.
Blueberries, potatoes, and rhododendrons thrive in it, but most vegetables start locking out nutrients below about pH 6.0 and grow pale and stunted no matter how much you feed them.
A measured lime application raises pH for the crops that need it — but test first, because the right rate depends on your own soil, not the county average.
USDA NRCS SSURGO
Wet ground
From county recordsAbout 23% of the ground across the New Hampshire Seacoast is mapped as hydric — wetland — soil. Rockingham County carries the most, at 25%.
If your lot falls in one of those pockets, a standard in-ground bed will fight waterlogging all season, and roots that need air will struggle.
Check how your own ground drains before you dig; raised beds or moisture-loving plantings turn a wet corner from a problem into a niche.
USDA NRCS SSURGO
Safe to Grow Here?
What the federal record shows across the New Hampshire Seacoast — and how to grow with it.
Across the New Hampshire Seacoast's 2 counties the federal record holds 2,413 documented sites, mostly Underground Storage Tanks (1,156), Brownfields (822) and Nitrate (180). The heaviest single county is Rockingham County, with 1,734.
That is a regional count, not a reading of any one lot — proximity to a documented site is information, not a diagnosis. Open the map outlined to the New Hampshire Seacoast to see which records sit where you actually grow.
Sources Checked
Summed across the 2 counties in the New Hampshire Seacoast
A note from Gnorman
What an experienced grower watches for around here
In and around the New Hampshire Seacoast, Toxics Release Inventory runs higher than the national average — 153 sites across the 2 counties in the New Hampshire Seacoast. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Your land is one point inside the New Hampshire Seacoast
Everything above resolves to the New Hampshire Seacoast as a whole — a footprint spanning USDA zones 6a. Your parcel sits in exactly one of them. Slope, tree cover, a low spot that pools cold air, and what is in the soil are all resolved at the address, and none of them are visible at region scale. That is the honest boundary of this page, and the reason the next step is a reading of your own ground rather than a better regional average.
Your Lot vs the New Hampshire Seacoast Average
New Hampshire Seacoast Average
- ●USDA Zones 6a, averaged across New Hampshire Seacoast
- ●One soil character for all of New Hampshire Seacoast
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not New Hampshire Seacoast's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in the New Hampshire Seacoast
Pull a site-specific report for your exact address in the New Hampshire Seacoast — soil, sun, drainage, frost risk, contamination, and scored plant recommendations.
Three things about your lot that New Hampshire Seacoast averages can't show:
We read public map data around The New Hampshire Seacoast — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the New Hampshire Seacoast average
How we know this about the New Hampshire Seacoast
The boundary: a cluster of neighboring counties. Growing regions have no official boundary, so this footprint is our published one, and every figure on this page was measured over the counties inside it rather than borrowed from the state around it.
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, aggregated across the footprint; the growing season from NOAA Regional Climate Centers ACIS 1991–2020 28°F normals, read at each member’s own record; boundaries from US Census TIGER/Line 2025; the contamination record from the federal sources named in that beat above; the soil from the USDA NRCS SSURGO survey, read at each member county’s own record and weighted to this footprint by land area. Where a member carries no record of its own, it is absent from the figure rather than filled in.
Common questions about the New Hampshire Seacoast
What hardiness zone is the New Hampshire Seacoast?
The New Hampshire Seacoast spans USDA hardiness zones 6a, aggregated from the USDA Agricultural Research Service Plant Hardiness Zone Map 2023 across the region's counties. Zones reflect average annual extreme minimum temperatures from 1991–2020 data.
How long is the growing season in the New Hampshire Seacoast?
Measured between 28°F hard freezes, the New Hampshire Seacoast's counties mostly run 187 to 188 frost-free days, median 188 (NOAA Regional Climate Centers ACIS, 1991–2020, over 2 member counties). That 1-day spread is the honest read — no single season describes 2 counties, and each county guide below carries its own.
When does frost risk end in the New Hampshire Seacoast?
Across the New Hampshire Seacoast, the middle half of member counties see their last 28°F hard freeze between Apr 18 and Apr 19 (median Apr 18), and their first fall freeze between Oct 22 and Oct 23. Those are hard freezes, not the last light frost: tender transplants wait for about May 9, and elevation decides which end of a 1-day spread you garden in.
What grows well in the New Hampshire Seacoast?
The New Hampshire Seacoast's conditions suit plants such as Potato, Apple, Sugar Maple, Blueberry, Lilac. What actually thrives on any one site still turns on its specific soil, sun, and drainage — we score each plant against the real conditions at your address.
How is the New Hampshire Seacoast defined?
The New Hampshire Seacoast is defined here as a curated cluster of 2 neighboring counties that share a growing character. Growing regions have no official boundary, so this footprint is our published one — every county in it is named on this page.
Which states does the New Hampshire Seacoast cover?
The New Hampshire Seacoast spans New Hampshire. Each state's full growing guide is linked on this page.
What other growing regions cover the same states?
The Upper Valley, White Mountains, The Lakes Region, Merrimack Valley, and The Monadnock Region share at least one state with the New Hampshire Seacoast. Growing regions overlap and interlock — a single address can sit inside more than one, which is why the precise read is always the parcel, not the region.
What this page reads at the New Hampshire Seacoast’s own scale
6 of the readings below were taken at the New Hampshire Seacoast's own scale — the zone 6a band across its footprint, a median 188-day season across its 2 counties and 2,413 documented federal contamination records across its 2 counties, 1,734 of them in Rockingham County alone; one is borrowed from a wider read, named and linked below.
Measured here
- The USDA hardiness band 6a aggregated across all 2 counties in the footprintUSDA PHZM 2023
- The boundary itself — the 2 counties this region is curated fromGrowable Ground subregion registry
- The growing character that makes this region distinct from the states it crossesGrowable Ground subregion registry
- The 28°F season across the footprint — the middle half of its 2 counties run 187 to 188 frost-free days, median 188NOAA Regional Climate Centers ACIS, 1991-2020
- The federal contamination record over the whole footprint — 2,413 documented federal contamination records across its 2 counties, 1,734 of them in Rockingham County aloneEPA, USGS and USDA federal site records
- The soil order mix across the footprint — 73% Inceptisols, topsoil pH 4.3–5.5, area-weighted across its 2 mapped countiesUSDA NRCS SSURGO
Inherited from a wider read
- The candidate plant list — its state's curated sets, merged and filtered to zones 6afrom New Hampshire
What this page can’t tell you
- Which end of the 1-day range your ground sits at — 187 days at one extreme, 188 at the other, decided mostly by elevationfrost dates explained →
- Which of those soils your own ground sits on — the survey maps them county-wide, and they change across a drivewaysoil types explained →
- The soil pH, drainage, sun hours, and frost pockets on one specific lotwhy one lot differs from the next →
Explore the New Hampshire Seacoast
State growing guides
Counties in this region
Other growing regions across New Hampshire
The Connecticut River's bi-state trench from Windsor to Hanover — 5a-5b valley-floor ground on both banks, warmer than the hills that rise from it, and a single growing community that has always ignored the state line.
Spanning Coos, Grafton, and Carroll counties, the White Mountains carry one of New Hampshire's shortest growing seasons — from 145 frost-free days in Coos County up to 162 in Grafton — across USDA hardiness zones 4b to 5b.
Winnipesaukee's tempering water gives the Lakes Region towns a solid 5b band and 174-191 measured frost-free days — noticeably gentler than the White Mountain country that begins one county north.
New Hampshire's Merrimack River corridor — Concord down through Manchester and Nashua — where the valley floor runs a shade milder (zone 6a at its southern end) than the 5b hills around it, buying growers a little more frost-free room than the uplands nearby.
Southwestern New Hampshire around Mount Monadnock and the hub city of Keene — cold zone-5b winters and a roughly 170-day growing season across the hills of Cheshire County.