New Hampshire spans USDA hardiness zones 3b-6b, with a growing season of about 171 frost-free days — a season that fits spring and fall plantings of cool-weather crops around a solid warm-season core.
In practice the season is written by 36-50 inches of annual rainfall, a median of roughly 1,870 growing-degree days (base 50°F), and about 2,500 winter chill hours for tree fruit. Dig almost anywhere and you'll meet glacial till, sandy loam, rocky loam, and river valley silt; how quickly they shed water is the first thing to learn about them. New Hampshire is not one growing region but several — from The Upper Valley, White Mountains, and Merrimack Valley — each with its own zone band and frost timing. Well-matched crops include apple, sugar maple, blueberry, and potato, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
Grounded inUSDA PHZM•NOAA Climate Normals•USDA NRCS SSURGO•GDD (PRISM 1991-2020 normals)•Chill hours (PRISM 1991-2020 normals)•USDA hardiness sub-region map•EPA FRS•USDA PLANTS•Growable Ground suitability scoring
New Hampshire spans zones 3b-6b, but your yard 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 — soil, climate, flood, and parcel records. How we handle your address.
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Distinct growing regions within New Hampshire — each has its own zones, soils, and signature crops.
New Hampshire: USDA zones 3b-6b, 145–188 frost-free days depending on the county, 10 counties.
The middle half of this state’s counties. Tender transplants usually wait 2–3 weeks past the last hard freeze. The shortest-season figure is New Hampshire's own county record — Coos County's measured 28°F normal, not a modeled floor.
New Hampshire does not have one growing season. Across all 100 of its towns that carry their own 30-year record, the shortest measured season is Colebrook's at 146 days and the longest is Hampton Beach's at 208 — a 62-day spread inside one state.
Neither end is a lone reading — another 8 towns measure within 10 days of Colebrook and 3 sit within 10 days of Hampton Beach. These are real pockets, so the number to plant against is your own town's, not the state average.
NOAA Regional Climate Centers ACIS (1991–2020), 30-year daily minimum record
Zone 3b-6b is New Hampshire's average, not your lot's — a low corner or a tree line moves it. Against New Hampshire's 171-day season, see what your own ground reads.
One answer for New Hampshire averages 10 counties whose growing seasons are 43 days apart — from 145 frost-free days in Coos County to 188 in Rockingham County. That is the same state, measured the same way, in the same years. Which end of it your county sits nearer decides what finishes before the first hard freeze.
The middle half of 10 counties runs 159–183 days, with a median of 169 days — a 43-day span end to end.
Measured across 10 counties, each carrying its own 28°F normal. NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze. A county with no record of its own is absent from the range rather than counted as zero — nothing here is interpolated to the state. Your own site sits somewhere inside this range; a parcel report resolves where.
The middle half of New Hampshire runs 159–183 frost-free days, and 4 of its 10 counties sit outside that — 2 on the short side, 2 on the long. A statewide planting date describes the middle well and the ends poorly, which is worth knowing before you follow one.
Under 159 frost-free days
2 counties
The end of the state that sets the planting calendar — start seed indoors here and the season stretches to meet the crop.
159–183 frost-free days
6 counties
0 of 6 shown
The middle half of the state, and the part a single statewide date describes well.
Over 183 frost-free days
2 counties
Long enough for a second succession of a quick crop after the first comes out.
Each county is placed by its own 28°F frost-free normal (NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze), the same figure its own guide page publishes. Elevation, slope and cold-air drainage move a yard within its county as well — which is the part only your address resolves.
The soil types that dominate New Hampshire — how each drains decides more about crop success than almost anything else. Tap any soil to learn what it is and how to work with it. Each photo is a representative profile of that soil type; the named series is where it was documented, which is often another state.
Drainage
Variable by the shovelful. Sandy till drains freely; dense, compacted till (hardpan) can perch water above it after snowmelt and heavy rain.
What thrives
Apples, stone fruits, brambles, and the whole northern vegetable garden do well on till — much of New England and the upper Midwest farms it. Deep-rooted perennials work through the stony structure happily.
Drainage
Fast. The sand fraction opens the soil up, so water moves through the root zone quickly and the surface rarely stays soggy. The trade is that nutrients ride out with the water.
What thrives
Root crops love it — carrots, potatoes, radishes, and onions size up cleanly in ground they can push through. Melons, sweet potatoes, asparagus, and most herbs appreciate the warmth and the drainage.
Loam threaded with stones — the signature of ground where glaciers, mountains, or shallow bedrock keep feeding rock into the topsoil. Every New England stone wall started as a rocky-loam garden bed.
Drainage
Good. The stones keep channels open through the profile, and rocky ground rarely waterlogs.
What thrives
Fruit trees, brambles, asparagus, herbs, and deep-rooted perennials thread between the stones happily. Root crops that need clean, straight runs — long carrots, parsnips — prefer a picked-over or raised bed.
The fine fraction of a river’s load — smooth, fertile silt spread across valley floors and bottomlands by generations of floods.
Drainage
Moderate. It holds moisture generously through dry spells; in the lowest bottomland positions it can stay wet late into spring.
What thrives
Bottomland silt grows legendary sweet corn, squash, melons, and greens — the moisture-holding fertility suits big, thirsty crops.
Soil data: USDA NRCS SSURGO · Soil types explained
Plants well-suited to New Hampshire's climate, soils, and growing season — each links to its full growing profile.
For most of the year, no — what changes is which crops still fit the days remaining. Across New Hampshire, cool-season planting typically opens about four weeks before the local last hard freeze — county medians put that freeze near Apr 27, with the middle half of counties between Apr 22 and May 4 (NOAA 1991–2020 climate normals). Tender transplants wait two to three weeks past it, and fall planting counts back from first freezes mostly between Oct 10 and Oct 21 — long-season crops need about 90 days of runway, quick greens only 30. Even past midsummer there is room for a true fall garden here, and garlic planted near the close carries the momentum into next year.
The plants New Hampshire put its name on — cultural emblems, not growing recommendations.
Syringa vulgaris
Designated 1919. In our plant library — see its full growing profile.
Betula papyrifera
Designated 1947. In our plant library — see its full growing profile.
White potato
Designated 2013.
Plants the USDA PLANTS Database documents as native and present in New Hampshire — a real per-state range, not just a zone match. Ordered by how closely each plant’s published hardiness range matches New Hampshire’s zones 3b-6b, so this is a shortlist by climate fit, not a ranking of which plants matter most here. Presence is statewide, so a plant may still be uncommon in your specific county; your state’s Cooperative Extension or a native-plant society is the local authority.
US-native plants whose hardiness range overlaps New Hampshire’s USDA zones 3b-6b but which USDA PLANTS doesn’t map to a single state range here. Zone overlap is a starting filter, not a range map.
What an experienced grower plans around here — each one has a move.
Very short season in the White Mountains (80-100 frost-free days)
In the mountains, fast varieties plus a cold frame or hoop house turn 90 days into a working season.
Rocky glacial soils throughout the state
Build up rather than dig out — a raised bed over cleared ground beats fighting granite for every planting hole.
Harsh winters with deep snow cover
Deep snow is a blanket, not a threat — plant to your true zone and the cover protects what the cold would test.
For cultivar selection, pest pressure, and planting-time guidance specific to New Hampshire, the UNH Cooperative Extension is the authoritative local source.
Safe to Grow Here?What the federal record shows across New Hampshire — and how to grow with it.
We checked the federal record across New Hampshire — 10,091 documented sites across 8 of the 9 source types we track.
The most significant on record: 82 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
New Hampshire carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Severity Distribution
across New Hampshire
Highest-Severity Sites
Know Before You Grow
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Everything above resolves to New Hampshire as a whole — a state whose own counties record seasons 43 days apart, and hardiness across zones 3b-6b. Your parcel sits at one point in that range, not in the middle of it. 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 state 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 statewide average.
State averages sketch the shape. Your soil, sun exposure, drainage, and microclimate decide what actually takes. Pull a site-specific report for your exact parcel.
Enter your address. We read your soil, sun, drainage, and frost dates, then score 1,086 plants against the real conditions on your land.
Three things about your lot that New Hampshire averages can't show:
We read public map data around New Hampshire — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the New Hampshire average
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read per county and aggregated to the state band; the growing season from NOAA Regional Climate Centers ACIS 1991–2020 28°F normals, read at each county’s own record; rainfall from NOAA Climate Normals; soils from USDA NRCS SSURGO; boundaries from US Census TIGER/Line 2025; the contamination record from the federal sources named in that beat above. Where a county carries no record of its own, it is absent from the figure rather than filled in.
New Hampshire spans USDA hardiness zones 3b-6b — which is to say winter's coldest night runs from about −35°F to 0°F depending where in New Hampshire you are, averaged over 1991–2020 (USDA PHZM 2023).
For most of the year, no — what changes is which crops still fit the days remaining. Across New Hampshire, cool-season planting typically opens about four weeks before the local last hard freeze — county medians put that freeze near Apr 27, with the middle half of counties between Apr 22 and May 4 (NOAA 1991–2020 climate normals). Tender transplants wait two to three weeks past it, and fall planting counts back from first freezes mostly between Oct 10 and Oct 21 — long-season crops need about 90 days of runway, quick greens only 30. Even past midsummer there is room for a true fall garden here, and garlic planted near the close carries the momentum into next year.
Across New Hampshire, the middle half of counties see their last hard freeze (28°F) between about Apr 22 and May 4, with a county median near Apr 27 (NOAA 1991–2020 climate normals). That marks the hard freeze, not the last light frost — lighter frosts keep biting past it, which is why tender transplants here wait until about May 18.
Measured between 28°F hard freezes, growing seasons across New Hampshire's counties mostly run about 160 to 181 days, with a county median near 171 (NOAA 1991–2020 climate normals). Tender crops get a somewhat shorter practical window, since lighter frosts reach a few weeks past the hard-freeze dates on both ends.
New Hampshire's zones 3b-6b support a wide range — strong performers include Apple, Sugar Maple, Blueberry, Potato, and Lilac. What actually takes on any one site comes down to its soil, sun, and drainage, and we score each plant against the real conditions at your address.
Officially, New Hampshire spans USDA zones 3b-6b (USDA PHZM 2023) — but a zone is a 30-year average of winter's coldest night across an area, and it can't see any one yard. A south-facing slope, a tree line, or a low frost pocket can shift a single site by half a zone either way, which is why neighboring gardeners often quote different numbers. We read the conditions at your exact address — soil, sun, slope, and frost — and score 1,086 plants against what's actually there.
The federal record across New Hampshire runs heavier than most — 10,091 documented sites, mostly Underground Storage Tanks entries (4,634) — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
Start with three facts. New Hampshire spans USDA zones 3b-6b, which sets what survives winter; last hard freezes range from about Apr 22 to May 4 across its counties (NOAA 1991–2020 climate normals); and 10,091 documented sites sit on the federal record here, so a soil test before food beds is the smart first step. From there, matching plants to your actual soil and sun is the fun part.
Everything above is measured at New Hampshire's scale — its 3b-6b band and its 171-day season. Your yard writes its own version of New Hampshire's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
6 of the readings below were taken at New Hampshire's own scale — the full zone 3b-6b span inside its borders, the 4 soil types that dominate its ground and 10,091 documented sites on its federal record; anything it cannot resolve at this scale is named below.
Measured here
What this page can’t tell you
Explore growing conditions by county — each has its own zone range and land area.
Explore growing conditions by city or town in New Hampshire.
New Hampshire shares its dominant growing region with these states — a useful comparison if you're weighing where a crop will behave the same way.
