The Upper Valley spans USDA hardiness zones 5a-5b — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
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. A short list that earns its place here — potato, garlic, kale, and apple — with any one site's soil, sun, and drainage making the final cut.
The Upper Valley spans New Hampshire and Vermont.
Your yard isn't all of the Upper Valley.
The Upper Valley spans USDA zones 5a-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 The Upper Valley — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
The Upper Valley — the short answer
The Upper Valley: USDA zones 5a-5b, 155–177 frost-free days, across 2 states.
- USDA zones
- 5a-5b
- USDA PHZM 2023, aggregated over the footprint
- Frost-free season
- 155–177 days
- NOAA Regional Climate Centers ACIS, 1991-2020
- Towns
- 13
- US Census TIGER/Line 2025
- Region type
- Town 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 Upper Valley
Plants matched to the Upper Valley's USDA zones 5a-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 Upper Valley
Plants the USDA PLANTS Database documents as native and present in all 2 states this region crosses, kept only where the published hardiness range meets the Upper Valley’s USDA zones 5a-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 around the Upper Valley
The USDA soil survey maps this ground county by county. These are those records weighted by land area across the three counties containing the Upper Valley — the ground the Upper Valley sits in, read at the only grain the survey publishes.
In the counties containing the Upper Valley, the ground is predominantly Spodosols, at 69% of mapped acres, followed by Inceptisols (27%), Entisols (3%) and Histosols (1%). The most extensive named soils are Tunbridge, Marlow, and Lyman.
60% of those acres are well drained, and another 14% moderately well drained, 11% somewhat excessively drained. Topsoil pH runs 4.3–5.5 between the lowest and the highest county on record. 4% of the footprint is classed prime farmland.
Soil order
Spodosols
Drainage
Well drained
Topsoil pH
4.3–5.5
Hydric soils
7%
Soil changes across a driveway, so which of these your own ground sits on is a parcel question rather than a regional one. Sullivan County holds the most wetland ground here, at 10% — soil types explained.
USDA NRCS SSURGO via Soil Data Access
What this means for growing in the Upper Valley
The soil survey reads this ground county by county, and the readings above are the record for the counties containing the Upper Valley. Here is what they mean for a garden here — and the move an experienced grower makes about each one.
Drainage
From county records60% of the mapped acres across the counties containing the Upper Valley are well drained — ground that drains quickly. The survey maps this ground county-wide, so it describes the setting the Upper Valley sits in rather than the valley floor alone.
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 counties containing the Upper Valley runs pH 4.3–5.5 — 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 Upper Valley — and how to grow with it.
Across the 3 counties containing the Upper Valley the federal record holds 2,229 documented sites, mostly Underground Storage Tanks (1,107), Brownfields (544) and Nitrate (394). The heaviest single county is Grafton County, with 1,131.
That is the containing counties' count — this region is a smaller piece of that ground, so it is context, not a reading of any one lot. Open the map outlined to the Upper Valley to see which records sit where you actually grow.
Sources Checked
Summed across the 3 counties containing the Upper Valley
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Your land is one point inside the Upper Valley
Everything above resolves to the Upper Valley as a whole — a footprint spanning USDA zones 5a-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 Upper Valley Average
Upper Valley Average
- ●USDA Zones 5a-5b, averaged across Upper Valley
- ●One soil character for all of Upper Valley
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not Upper Valley's 5a-5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in the Upper Valley
Pull a site-specific report for your exact address in the Upper Valley — soil, sun, drainage, frost risk, contamination, and scored plant recommendations.
Three things about your lot that Upper Valley averages can't show:
We read public map data around The Upper Valley — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Upper Valley average
How we know this about the Upper Valley
The boundary: the region's own towns — a footprint finer than any county, because the county average would misread this microclimate. Growing regions have no official boundary, so this footprint is our published one, and every figure on this page was measured over the towns 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 Upper Valley
What hardiness zone is the Upper Valley?
The Upper Valley spans USDA hardiness zones 5a-5b, aggregated from the USDA Agricultural Research Service Plant Hardiness Zone Map 2023 across the region's own towns. Zones reflect average annual extreme minimum temperatures from 1991–2020 data.
How long is the growing season in the Upper Valley?
Measured between 28°F hard freezes, the Upper Valley's towns mostly run 165 to 172 frost-free days, median 168 (NOAA Regional Climate Centers ACIS, 1991–2020, over 13 member towns). That 7-day spread is the honest read — no single season describes 13 towns, and each town guide below carries its own.
When does frost risk end in the Upper Valley?
Across the Upper Valley, the middle half of member towns see their last 28°F hard freeze between Apr 28 and May 1 (median Apr 30), and their first fall freeze between Oct 13 and Oct 17. Those are hard freezes, not the last light frost: tender transplants wait for about May 21, and elevation decides which end of a 3-day spread you garden in.
What grows well in the Upper Valley?
The Upper Valley's conditions suit plants such as Potato, Garlic, Kale, Apple, Sugar Maple, Blueberry. 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 Upper Valley defined?
The Upper Valley is a true microclimate — smaller than the counties that contain it, with a growing reality of its own. So this page is built from the region's own 13 towns, each carrying its own hardiness zone and frost record, rather than from a county average measured somewhere else.
Which states does the Upper Valley cover?
The Upper Valley spans New Hampshire and Vermont. Each state's full growing guide is linked on this page.
What other growing regions cover the same states?
Champlain Valley, The Green Mountains, The Northeast Kingdom, White Mountains, The Lakes Region, and Merrimack Valley share at least one state with the Upper Valley. 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 Upper Valley’s own scale
6 of the readings below were taken at the Upper Valley's own scale — the zone 5a-5b band across its footprint, a median 168-day season across its 13 towns and 2,229 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 5a-5b aggregated across all 13 towns in the footprintUSDA PHZM 2023
- The boundary itself — the 13 towns 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 13 towns run 165 to 172 frost-free days, median 168NOAA Regional Climate Centers ACIS, 1991-2020
- The federal contamination record over the whole footprint — 2,229 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 — 69% Spodosols, topsoil pH 4.3–5.5, area-weighted across its 3 mapped countiesUSDA NRCS SSURGO
Inherited from a wider read
- The candidate plant list — all 2 member states' curated sets, merged and filtered to zones 5a-5bfrom New Hampshire and Vermont
What this page can’t tell you
- Which end of the 7-day range your ground sits at — 165 days at one extreme, 172 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 Upper Valley
State growing guides
Towns in this region
Counties containing this region
Other growing regions across New Hampshire and Vermont
The lake-tempered lowland on both shores of Lake Champlain — clay and silt plains that make the warmest, driest, and most productive farm ground in Vermont, with apple and cold-climate wine country on the New York shore.
Vermont's forested spine of cold uplands and sheltered valleys — maple, apples, and cold-hardy market gardens on acidic mountain loams under a short northern season.
Vermont's Northeast Kingdom — Caledonia, Essex, and Orleans counties — sits entirely in USDA hardiness zone 4b, giving its three counties a short, uniformly cold frost-free season of roughly 146 to 156 days.
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.