New Hampshire spans USDA hardiness zones 3b-6a, with a growing season of about 170 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 2,900 growing-degree days (base 50°F), and about 1,500 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. 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 2023•NOAA Climate Normals•USDA NRCS SSURGO•GDD aggregate (Cornell CALS)•Chill-hour aggregate (MSU Extension)•EPA FRS•USDA PLANTS•Growable Ground suitability scoring
New Hampshire spans zones 3b-6a, but your yard sits in exactly one — and slope, tree cover, and low spots nudge it further. Enter your address and we'll score 1,112 plants against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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USDA Zones
3b-6a
USDA PHZM 2023
Last Frost
May 1 - Jun 1
NOAA 30-yr Normals
First Frost
Sep 10 - Oct 10
NOAA 30-yr Normals
Annual Rainfall
36-50 inches
NOAA Climate Normals
Zone maps are averages across New Hampshire. Your yard's slope, trees, and frost pockets shift what actually grows — see your land's exact reading.
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.
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.
See the glacial-till profile — rocky loam is the same stone-threaded ground.
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.
See the alluvial profile — river silt is its fine, fertile bottomland fraction.
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 17, with the middle half of counties between Apr 13 and Apr 20 (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 31 and Nov 7 — long-season crops need about 90 days of runway, quick greens only 30. Here the season winds down slowly: late sowings, a real autumn harvest, and garlic in the ground before the first hard freeze.
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. 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-6a 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.
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 1,112 plants against the real conditions on your land.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
New Hampshire spans USDA hardiness zones 3b-6a, per the USDA Plant Hardiness Zone Map 2023. Zones reflect average annual extreme minimum temperatures from 1991–2020 weather data.
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 17, with the middle half of counties between Apr 13 and Apr 20 (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 31 and Nov 7 — long-season crops need about 90 days of runway, quick greens only 30. Here the season winds down slowly: late sowings, a real autumn harvest, and garlic in the ground before the first hard freeze.
Across New Hampshire, the middle half of counties see their last hard freeze (28°F) between about Apr 13 and Apr 20, with a county median near Apr 17 (NOAA 1991–2020 climate normals). That marks the hard freeze, not the last light frost — light frosts can still bite for a few more weeks, so tender transplants usually wait another 2–3 weeks.
Measured between 28°F hard freezes, growing seasons across New Hampshire's counties mostly run about 195 to 207 days, with a county median near 204 (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-6a 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-6a (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 1,112 plants against what's actually there.
The federal record across New Hampshire runs heavier than most — 10,091 documented sites — 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-6a, which sets what survives winter; last hard freezes range from about Apr 13 to Apr 20 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 on this page is a New Hampshire average. Your yard writes its own version — we read soil, sun, drainage, and frost at your exact address. Try it for 14 days — no card required.
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.
