Colebrook, New Hampshire, sits in USDA hardiness zone 4a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Crops well matched to these conditions include cabbage, cranberry, cilantro, and collard greens — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Even in Colebrook, no two yards are alike.
A low spot, a south-facing slope, or a stand of trees moves the frost date and sun across a single Colebrook lot. 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 Colebrook — soil, climate, flood, and parcel records. How we handle your address.
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Colebrook — the short answer
Colebrook, New Hampshire: USDA zone 4a, about 146 days between hard freezes, across 2K acres of town.
- USDA zone
- 4a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 13
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 6
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~146
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 2K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 4a is Colebrook's average, not your lot's — a low corner or a tree line moves it. Against Colebrook's 146-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Colebrook
Each reading below is measured for Colebrook itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredColebrook runs about 146 days between hard freezes — a short growing season.
Long-maturing crops like melons, sweet potatoes, and winter squash can run out of runway before the first hard freeze, ripening late or not at all.
Lead with fast-maturing varieties, and stretch the season on both ends with cold frames, low tunnels, or a greenhouse.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredColebrook sits in USDA hardiness zone 4a.
The zone sets which perennials, shrubs, and fruit trees live through an average winter here — a plant rated for a colder zone is a safe bet, one rated warmer needs winter protection or gets treated as an annual.
Match perennials and fruit to the zone before you buy, so nothing you plant is a gamble against the cold.
USDA PHZM 2023
The kind of country Colebrook is in
Colebrook sits in the Northeastern Highlands — EPA Level III, inside the wider Northern Forests. That is read at Colebrook's own centroid rather than borrowed from Coos County.
What Grows in Colebrook
Every plant below cleared Colebrook's own zone 4a and its 146-day season. Each card opens that plant's New Hampshire profile. How we score.
Is it too late to plant in Colebrook?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Apr 15; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 13 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 6 — long-season crops need about 90 days of runway, quick greens only 30. Even here the calendar’s edges hold value: thirty-day greens late in the window, then garlic and a rested bed for spring.
What's on the federal record near Colebrook
Closest first, within ~10 miles of Colebrook. Listing isn't leaking, and distance isn't exposure.
- PARK ST APARTMENTSUnderground Storage Tanks · 450 ft
- COLEBROOK HOUSEUnderground Storage Tanks · 500 ft
- NORTHWOODS TRUCK STOP INCUnderground Storage Tanks · 550 ft
- BROOKS CHEVROLET INCUnderground Storage Tanks · 550 ft
- NH-CTW 3Nitrate · 600 ft
- FIRST COLEBROOK BANKUnderground Storage Tanks · 600 ft
- BIG APPLE CONVENIENCE STORE 1108Underground Storage Tanks · 650 ft
- MOHAWK CHEVRONUnderground Storage Tanks · 650 ft
- WALGREENS 19398Brownfields · 700 ft
- KSL HOLDINGS-RITE AID PROPERTYUnderground Storage Tanks · 700 ft
- VICS GETTY STATIONUnderground Storage Tanks · 700 ft
- NUGENT MOTOR CO & MOBILE STATIONUnderground Storage Tanks · 850 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Colebrook's center, not your beds. Run your own address for what's upwind of you specifically.
Environmental Intelligence
The counts behind that headline — every source type on the record near Colebrook.
Total Sites
102
within ~10 miles of Colebrook
Risk Level
Moderate
Highest-severity
2 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Colebrook
Severity Distribution
within ~10 miles of Colebrook
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Colebrook, Nitrate runs higher than the national average — 32 sites within ~10 miles of Colebrook. That's not a problem with your land — it's information about 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).
Check your specific parcel in Colebrook
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,086 plant recommendations.
25+ data sources read at your address, not the Colebrook average
Your land is one point inside Colebrook
Everything above resolves to Colebrook as a whole — one PHZM band and one 28°F frost record, read across 2K acres. Your parcel is one point inside that footprint. 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 town 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 local average.
Your Lot vs the Colebrook Average
Colebrook Average
- ●USDA Zones 4a, averaged across Colebrook
- ●One soil character for all of Colebrook
- ●Frost dates read at Colebrook's scale: May 13 to Oct 6
YOUR Parcel
- ✓Your exact zone, not Colebrook's 4a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Colebrook
Pull a site-specific report for your exact address in Colebrook, New Hampshire — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Colebrook averages can't show:
We read public map data around Colebrook — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Colebrook average
How we know this about Colebrook
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this town’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Colebrook’s own record; boundaries and acreage from US Census TIGER/Line 2025; the contamination records from the federal sources named in their beats above. Soil is not read at town grain anywhere on this page — there is no town-resolution survey in our data, which is why you will find no soil grid here rather than a statewide one wearing a local label. The resolution ledger below names every figure this page inherited.
Common questions about Colebrook
When does frost risk typically end in Colebrook?
The last hard freeze (28°F) in Colebrook typically lands around May 13, per NOAA 1991–2020 climate normals — earlier than the light-frost dates most charts quote. 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 Jun 3.
When is the first frost in Colebrook?
The first hard freeze (28°F) in Colebrook typically arrives around Oct 6, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 22, so the watching starts about Sep 6 — about 146 days after the spring freeze cleared.
How long is the growing season in Colebrook?
Measured between 28°F hard freezes, Colebrook sees about 146 frost-free days — roughly May 13 through Oct 6, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 3 to Sep 22, about 111 days.
Is the soil safe to grow vegetables in Colebrook?
The federal record around Colebrook shows 102 documented sites, mostly Underground Storage Tanks entries (49), the nearest Underground Storage Tanks record under a tenth of a mile out — a typical footprint for a growing area, and proximity to a documented site is information, not a diagnosis of any one yard. It's worth seeing which recorded sites sit closest to where you grow, and testing the soil before new food beds near any of them.
How do gardeners stretch the season in Colebrook?
With about 146 frost-free days between hard freezes, Colebrook rewards the classic extension moves: floating row cover buys roughly two to four extra weeks at each shoulder — on this season that is a working window nearer 174 to 202 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 13 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Colebrook's scale — its 4a band and its 146-day season. Your yard writes its own version of Colebrook's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
What this page reads at Colebrook’s own scale
6 of the readings below were taken at Colebrook's own scale — its own ~146-day season between 28°F freezes, the 1,676 acres it covers and 102 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Colebrook's own USDA hardiness band, zones 4aUSDA PHZM 2023
- Colebrook's own 28°F hard-freeze dates, about May 13 and Oct 6 and the ~146-day span between themNOAA 1991–2020 Climate Normals
- 102 documented contamination sites on the federal record near Colebrook, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Colebrook's boundary and the 1,676 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4a and a ~146-day seasonGrowable Ground crop-matching engine
- The ecoregion at Colebrook's own centroid, the Northeastern HighlandsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Colebrook's 1,676 acres read through its county's SSURGO summaryfrom Coos County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Coos County
- The growing challenges every New Hampshire grower plans around — written at state scale, so they stay on the state guidefrom New Hampshire
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Coos County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Colebrook's 1,676 acreswhy one lot differs from the next →
- Which side of Colebrook you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,676 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record under a tenth of a mile out, measured from the town centrehow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — measured at your address, and averaged away by any Colebrook-wide figureread your own land →
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