Culbertson, Montana, sits in USDA hardiness zone 3b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
These conditions suit cabbage, cranberry, epazote, and collard greens — a starting list any specific site will trim or extend with its own soil, sun, and drainage.
Even in Culbertson, 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 Culbertson 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 Culbertson — soil, climate, flood, and parcel records. How we handle your address.
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Culbertson — the short answer
Culbertson, Montana: USDA zone 3b, about 148 days between hard freezes, across 714 acres of town.
- USDA zone
- 3b
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 6
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 1
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~148
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 714 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 3b is Culbertson's average, not your lot's — a low corner or a tree line moves it. Against Culbertson's 148-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Culbertson
Each reading below is measured for Culbertson itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredCulbertson runs about 148 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
MeasuredCulbertson sits in USDA hardiness zone 3b.
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 Culbertson is in
Culbertson sits in the Northwestern Glaciated Plains — EPA Level III, inside the wider Great Plains. That is read at Culbertson's own centroid rather than borrowed from Roosevelt County.
What Grows in Culbertson
Every plant below cleared Culbertson's own zone 3b and its 148-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in Culbertson?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Apr 8; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 6 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 1 — long-season crops need about 90 days of runway, quick greens only 30. Short seasons reward decisiveness — quick-maturing varieties late, hardy greens under cover, and next year’s garlic in the ground before it closes.
What's on the federal record near Culbertson
Closest first, within ~10 miles of Culbertson. Listing isn't leaking, and distance isn't exposure.
- MCKINNEY MOTORSUnderground Storage Tanks · 250 ft
- BN CULBERTSONUnderground Storage Tanks · 500 ft
- LARSEN CONSTRUCTIONUnderground Storage Tanks · 600 ft
- MILLER OIL COMPANY INCBrownfields · 600 ft
- ANDERSON CONOCO CULBERTSONUnderground Storage Tanks · 650 ft
- CULBERTSON MT CRUDE OIL DERAILMENTBrownfields · 700 ft
- CULBERTSON IMPLEMENT COUnderground Storage Tanks · 1000 ft
- OELKERS SERVICE CENTERUnderground Storage Tanks · 1400 ft
- OELKERS SERVICENTERBrownfields · 1400 ft
- VAL AM STOP & GO LLCUnderground Storage Tanks · 1600 ft
- MISSOURI RIVER LOGISTICSUnderground Storage Tanks · 2000 ft
- TRIPLE M SINCLAIRUnderground Storage Tanks · 2000 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Culbertson'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 Culbertson.
Total Sites
52
within ~10 miles of Culbertson
Risk Level
Moderate
Highest-severity
1 Toxics Release Inventory facility
Sources Checked
within ~10 miles of Culbertson
Severity Distribution
within ~10 miles of Culbertson
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Culbertson, Nitrate runs higher than the national average — 22 sites within ~10 miles of Culbertson. 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).
Check your specific parcel in Culbertson
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 Culbertson average
Your land is one point inside Culbertson
Everything above resolves to Culbertson as a whole — one PHZM band and one 28°F frost record, read across 714 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 Culbertson Average
Culbertson Average
- ●USDA Zones 3b, averaged across Culbertson
- ●One soil character for all of Culbertson
- ●Frost dates read at Culbertson's scale: May 6 to Oct 1
YOUR Parcel
- ✓Your exact zone, not Culbertson's 3b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Culbertson
Pull a site-specific report for your exact address in Culbertson, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Culbertson averages can't show:
We read public map data around Culbertson — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Culbertson average
How we know this about Culbertson
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 Culbertson’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 Culbertson
When does frost risk typically end in Culbertson?
The last hard freeze (28°F) in Culbertson typically lands around May 6, 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 May 27.
When is the first frost in Culbertson?
The first hard freeze (28°F) in Culbertson typically arrives around Oct 1, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 17, so the watching starts about Sep 1 — about 148 days after the spring freeze cleared.
How long is the growing season in Culbertson?
Measured between 28°F hard freezes, Culbertson sees about 148 frost-free days — roughly May 6 through Oct 1, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 27 to Sep 17, about 113 days.
Is the soil safe to grow vegetables in Culbertson?
The federal record around Culbertson shows 52 documented sites, mostly Underground Storage Tanks entries (25), 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 Culbertson?
With about 148 frost-free days between hard freezes, Culbertson 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 176 to 204 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 6 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Culbertson's scale — its 3b band and its 148-day season. Your yard writes its own version of Culbertson'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 Culbertson’s own scale
6 of the readings below were taken at Culbertson's own scale — its own ~148-day season between 28°F freezes, the 714 acres it covers and 52 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Culbertson's own USDA hardiness band, zones 3bUSDA PHZM 2023
- Culbertson's own 28°F hard-freeze dates, about May 6 and Oct 1 and the ~148-day span between themNOAA 1991–2020 Climate Normals
- 52 documented contamination sites on the federal record near Culbertson, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Culbertson's boundary and the 714 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 3b and a ~148-day seasonGrowable Ground crop-matching engine
- The ecoregion at Culbertson's own centroid, the Northwestern Glaciated PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Culbertson's 714 acres read through its county's SSURGO summaryfrom Roosevelt County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Roosevelt County
- The growing challenges every Montana grower plans around — written at state scale, so they stay on the state guidefrom Montana
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Roosevelt County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Culbertson's 714 acreswhy one lot differs from the next →
- Which side of Culbertson you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 714 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 Culbertson-wide figureread your own land →
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