The White Mountains spans USDA hardiness zones 4b-5b — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
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. Reliable performers under these conditions include potato, apple, sugar maple, and blueberry; what your own ground favors still comes down to its soil, sun, and drainage.
The White Mountains spans New Hampshire.
Your yard isn't all of the White Mountains.
The White Mountains spans USDA zones 4b-5b, 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 White Mountains — soil, climate, flood, and parcel records. How we handle your address.
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The White Mountains — the short answer
The White Mountains: USDA zones 4b-5b, 145–162 frost-free days, in New Hampshire.
- USDA zones
- 4b-5b
- USDA PHZM 2023, aggregated over the footprint
- Frost-free season
- 145–162 days
- NOAA Regional Climate Centers ACIS, 1991-2020
- Counties
- 3
- 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 White Mountains
Plants matched to the White Mountains' USDA zones 4b-5b, 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 White Mountains
Plants the USDA PLANTS Database documents as native and present in this region’s state, kept only where the published hardiness range meets the White Mountains’s USDA zones 4b-5b — 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 White Mountains
The USDA soil survey maps this ground county by county. These are those records weighted by land area across three member counties — this region’s own profile, not a state figure.
The ground is predominantly Spodosols, at 75% of mapped acres, followed by Inceptisols (19%), Entisols (3%) and Histosols (3%). The most extensive named soils are Tunbridge, Marlow, and Becket.
53% of those acres are well drained, and another 19% moderately well drained, 9% poorly drained. Topsoil pH runs 4.6–5.2 between the lowest and the highest county on record. 3% of the footprint is classed prime farmland.
Soil order
Spodosols
Drainage
Well drained
Topsoil pH
4.6–5.2
Hydric soils
13%
Soil changes across a driveway, so which of these your own ground sits on is a parcel question rather than a regional one. Coos County holds the most wetland ground here, at 20% — soil types explained.
USDA NRCS SSURGO via Soil Data Access
What this means for growing in the White Mountains
The soil survey reads this ground county by county, and the readings above are those records summed across the White Mountains. Here is what they mean for a garden here — and the move an experienced grower makes about each one.
Drainage
From county records53% of the mapped acres across the White Mountains are well drained — ground that drains quickly. That is area-weighted across all three 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 White Mountains runs pH 4.6–5.2 — acidic in all three 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
Safe to Grow Here?
What the federal record shows across the White Mountains — and how to grow with it.
Across the White Mountains' 3 counties the federal record holds 2,458 documented sites, mostly Underground Storage Tanks (1,061), Nitrate (872) and Brownfields (363). The heaviest single county is Grafton County, with 1,131.
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 White Mountains to see which records sit where you actually grow.
Sources Checked
Summed across the 3 counties in the White Mountains
A note from Gnorman
What an experienced grower watches for around here
In and around the White Mountains, Nitrate runs higher than the national average — 872 sites across the 3 counties in the White Mountains. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Your land is one point inside the White Mountains
Everything above resolves to the White Mountains as a whole — a footprint spanning USDA zones 4b-5b. 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 White Mountains Average
White Mountains Average
- ●USDA Zones 4b-5b, averaged across White Mountains
- ●One soil character for all of White Mountains
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not White Mountains' 4b-5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in the White Mountains
Pull a site-specific report for your exact address in the White Mountains — soil, sun, drainage, frost risk, contamination, and scored plant recommendations.
Three things about your lot that White Mountains averages can't show:
We read public map data around The White Mountains — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the White Mountains average
How we know this about the White Mountains
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 White Mountains
What hardiness zone is the White Mountains?
The White Mountains spans USDA hardiness zones 4b-5b, 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 White Mountains?
Measured between 28°F hard freezes, the White Mountains' counties mostly run 150 to 159 frost-free days, median 155 (NOAA Regional Climate Centers ACIS, 1991–2020, over 3 member counties). That 9-day spread is the honest read — no single season describes 3 counties, and each county guide below carries its own.
When does frost risk end in the White Mountains?
Across the White Mountains, the middle half of member counties see their last 28°F hard freeze between May 4 and May 9 (median May 4), and their first fall freeze between Oct 6 and Oct 10. Those are hard freezes, not the last light frost: tender transplants wait for about May 25, and elevation decides which end of a 5-day spread you garden in.
What grows well in the White Mountains?
The White Mountains' 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 White Mountains defined?
The White Mountains is defined here as a curated cluster of 3 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 White Mountains cover?
The White Mountains 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, The Lakes Region, Merrimack Valley, New Hampshire Seacoast, and The Monadnock Region share at least one state with the White Mountains. 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 White Mountains’s own scale
6 of the readings below were taken at the White Mountains' own scale — the zone 4b-5b band across its footprint, a median 155-day season across its 3 counties and 2,458 documented federal contamination records across its 3 counties, 1,131 of them in Grafton County alone; one is borrowed from a wider read, named and linked below.
Measured here
- The USDA hardiness band 4b-5b aggregated across all 3 counties in the footprintUSDA PHZM 2023
- The boundary itself — the 3 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 3 counties run 150 to 159 frost-free days, median 155NOAA Regional Climate Centers ACIS, 1991-2020
- The federal contamination record over the whole footprint — 2,458 documented federal contamination records across its 3 counties, 1,131 of them in Grafton County aloneEPA, USGS and USDA federal site records
- The soil order mix across the footprint — 75% Spodosols, topsoil pH 4.6–5.2, area-weighted across its 3 mapped countiesUSDA NRCS SSURGO
Inherited from a wider read
- The candidate plant list — its state's curated sets, merged and filtered to zones 4b-5bfrom New Hampshire
What this page can’t tell you
- Which end of the 9-day range your ground sits at — 150 days at one extreme, 159 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 White Mountains
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.
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.
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).
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.