Big Timber, Montana, sits in USDA hardiness zone 5a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Among the crops suited to this profile: cabbage, cranberry, lavender, and collard greens. The site-level story — soil, sun, drainage — decides the rest.
Even in Big Timber, 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 Big Timber 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 Big Timber — soil, climate, flood, and parcel records. How we handle your address.
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Big Timber — the short answer
Big Timber, Montana: USDA zone 5a, about 154 days between hard freezes, across 625 acres of city.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 5
- 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
- ~154
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 625 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 5a is Big Timber's average, not your lot's — a low corner or a tree line moves it. Against Big Timber's 154-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Big Timber
Each reading below is measured for Big Timber itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredBig Timber runs about 154 days between hard freezes — a moderate growing season.
There is room for the full run of cool-season crops plus a warm-season main crop, but the calendar is tight enough that a late spring or early fall frost still decides how much finishes.
Time warm-season transplants to your last hard freeze, and a few weeks of season extension turns a near-miss harvest into a sure one.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredBig Timber sits in USDA hardiness zone 5a.
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 Big Timber is in
Big Timber sits in the Northwestern Great Plains — EPA Level III, inside the wider Great Plains. That is read at Big Timber's own centroid rather than borrowed from Sweet Grass County.
What Grows in Big Timber
Every plant below cleared Big Timber's own zone 5a and its 154-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in Big Timber?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Apr 7; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 5 (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. Late in the year the fall bench takes over — quick greens, radishes, and garlic that repays you next summer.
What's on the federal record near Big Timber
Closest first, within ~10 miles of Big Timber. Listing isn't leaking, and distance isn't exposure.
- JARRETTS UPHOLSTERYUnderground Storage Tanks · 250 ft
- AT & T COMMUNICATIONS BIG TIMBERUnderground Storage Tanks · 900 ft
- THE STORE BIG TIMBERUnderground Storage Tanks · 900 ft
- LEO ARLIANUnderground Storage Tanks · 900 ft
- TODD CONSTRUCTION INCUnderground Storage Tanks · 900 ft
- STILLWATER MINING CO EAST BOULDER MINEToxics Release Inventory · 1300 ft
- STILLWATER MINING CO EAST BOULDER MINEBrownfields · 1300 ft
- STETSON FORD INCUnderground Storage Tanks · 1300 ft
- STETSON FORDBrownfields · 1300 ft
- CITY OF BIG TIMBER 113 E 3RDUnderground Storage Tanks · 1300 ft
- CITY OF BIG TIMBER 107 E 3RDUnderground Storage Tanks · 1400 ft
- BIG TIMBER BRANCH OF LAUREL COOPUnderground Storage Tanks · 1400 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Big Timber'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 Big Timber.
Total Sites
78
within ~10 miles of Big Timber
Risk Level
Moderate
Highest-severity
1 Toxics Release Inventory facility
Sources Checked
within ~10 miles of Big Timber
Severity Distribution
within ~10 miles of Big Timber
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Big Timber, Nitrate runs higher than the national average — 38 sites within ~10 miles of Big Timber. 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 Big Timber
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 Big Timber average
Your land is one point inside Big Timber
Everything above resolves to Big Timber as a whole — one PHZM band and one 28°F frost record, read across 625 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 city 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 Big Timber Average
Big Timber Average
- ●USDA Zones 5a, averaged across Big Timber
- ●One soil character for all of Big Timber
- ●Frost dates read at Big Timber's scale: May 5 to Oct 6
YOUR Parcel
- ✓Your exact zone, not Big Timber's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Big Timber
Pull a site-specific report for your exact address in Big Timber, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Big Timber averages can't show:
We read public map data around Big Timber — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Big Timber average
How we know this about Big Timber
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Big Timber’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 city grain anywhere on this page — there is no city-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 Big Timber
When does frost risk typically end in Big Timber?
The last hard freeze (28°F) in Big Timber typically lands around May 5, 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 26.
When is the first frost in Big Timber?
The first hard freeze (28°F) in Big Timber 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 154 days after the spring freeze cleared.
How long is the growing season in Big Timber?
Measured between 28°F hard freezes, Big Timber sees about 154 frost-free days — roughly May 5 through Oct 6, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 26 to Sep 22, about 119 days.
Is the soil safe to grow vegetables in Big Timber?
The federal record around Big Timber shows 78 documented sites, mostly Nitrate entries (38), 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 I protect my plants from frost in Big Timber?
From about Sep 6 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Oct 6 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Oct 6. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Big Timber's scale — its 5a band and its 154-day season. Your yard writes its own version of Big Timber'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 Big Timber’s own scale
6 of the readings below were taken at Big Timber's own scale — its own ~154-day season between 28°F freezes, the 625 acres it covers and 78 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Big Timber's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Big Timber's own 28°F hard-freeze dates, about May 5 and Oct 6 and the ~154-day span between themNOAA 1991–2020 Climate Normals
- 78 documented contamination sites on the federal record near Big Timber, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Big Timber's boundary and the 625 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~154-day seasonGrowable Ground crop-matching engine
- The ecoregion at Big Timber's own centroid, the Northwestern Great PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Big Timber's 625 acres read through its county's SSURGO summaryfrom Sweet Grass County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Sweet Grass 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 Sweet Grass County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Big Timber's 625 acreswhy one lot differs from the next →
- Which side of Big Timber you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 625 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 Big Timber-wide figureread your own land →
More in Montana
Wider growing context
What grows across MontanaBig Timber sits outside our named growing regions, so Montana as a whole is its closest context here.
Nearby growing guides