Fort Smith, Montana, sits in USDA hardiness zone 5b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Crops well matched to these conditions include cabbage, cranberry, lavender, and collard greens — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Even in Fort Smith, 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 Fort Smith 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 Fort Smith — soil, climate, flood, and parcel records. How we handle your address.
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Fort Smith — the short answer
Fort Smith, Montana: USDA zone 5b, about 174 days between hard freezes, across 883 acres of town.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 20
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 11
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~174
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 883 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 5b is Fort Smith's average, not your lot's — a low corner or a tree line moves it. Against Fort Smith's 174-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Fort Smith
Each reading below is measured for Fort Smith itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredFort Smith runs about 174 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
MeasuredFort Smith sits in USDA hardiness zone 5b.
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 Fort Smith is in
Fort Smith sits in the Northwestern Great Plains — EPA Level III, inside the wider Great Plains. That is read at Fort Smith's own centroid rather than borrowed from Big Horn County.
What Grows in Fort Smith
Every plant below cleared Fort Smith's own zone 5b and its 174-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in Fort Smith?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 23; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 20 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 11 — long-season crops need about 90 days of runway, quick greens only 30. Even past midsummer there is room for a true fall garden here, and garlic planted near the close carries the momentum into next year.
What's on the federal record near Fort Smith
Closest first, within ~10 miles of Fort Smith. Listing isn't leaking, and distance isn't exposure.
- OK A BEH MARINAUnderground Storage Tanks · 1900 ft
- USBR YELLOWTAIL DAM AND POWER PLANTSuperfund · 1900 ft
- U.S. NATL. PARK SERVICE BIGHORN CANYON NRAToxics Release Inventory · 1900 ft
- BIGHORN CANYON NATL REC AREA FORT SMITHBrownfields · 2300 ft
- USBR YELLOWTAIL DAMBrownfields · 1.2 mi
- YELLOWTAIL MARKETUnderground Storage Tanks · 1.2 mi
- BIGHORN CANYON MAINTENANCE FACILITYUnderground Storage Tanks · 1.4 mi
- FORT SMITH SERVICE CENTERUnderground Storage Tanks · 3.5 mi
- 05S31E35CCC 02Nitrate · 4.3 mi
- 05S31E36DBB 01Nitrate · 5.5 mi
- 05S32E20BAA 01Nitrate · 8.4 mi
- 5S-32E-20aba01Nitrate · 8.6 mi
Measured from Fort Smith'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 Fort Smith.
Total Sites
16
within ~10 miles of Fort Smith
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of Fort Smith
Severity Distribution
within ~10 miles of Fort Smith
Highest-Severity Sites
Know Before You Grow
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
- •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.
Check your specific parcel in Fort Smith
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 Fort Smith average
Your land is one point inside Fort Smith
Everything above resolves to Fort Smith as a whole — one PHZM band and one 28°F frost record, read across 883 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 Fort Smith Average
Fort Smith Average
- ●USDA Zones 5b, averaged across Fort Smith
- ●One soil character for all of Fort Smith
- ●Frost dates read at Fort Smith's scale: Apr 20 to Oct 11
YOUR Parcel
- ✓Your exact zone, not Fort Smith's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Fort Smith
Pull a site-specific report for your exact address in Fort Smith, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Fort Smith averages can't show:
We read public map data around Fort Smith — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Fort Smith average
How we know this about Fort Smith
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 Fort Smith’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 Fort Smith
When does frost risk typically end in Fort Smith?
The last hard freeze (28°F) in Fort Smith typically lands around Apr 20, 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 11.
When is the first frost in Fort Smith?
The first hard freeze (28°F) in Fort Smith typically arrives around Oct 11, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 27, so the watching starts about Sep 11 — about 174 days after the spring freeze cleared.
How long is the growing season in Fort Smith?
Measured between 28°F hard freezes, Fort Smith sees about 174 frost-free days — roughly Apr 20 through Oct 11, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 11 to Sep 27, about 139 days.
Is the soil safe to grow vegetables in Fort Smith?
The federal record around Fort Smith is a meaningful one — 16 documented sites, mostly Nitrate entries (8), the nearest Underground Storage Tanks record about 0.4 miles out — so a soil test before new food beds is a sensible precaution here, not a reason to hold back from growing. Remember that proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what sits where.
How do I protect my plants from frost in Fort Smith?
From about Sep 11 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 11 (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 11. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Fort Smith's scale — its 5b band and its 174-day season. Your yard writes its own version of Fort Smith'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 Fort Smith’s own scale
6 of the readings below were taken at Fort Smith's own scale — its own ~174-day season between 28°F freezes, the 883 acres it covers and 16 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Fort Smith's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Fort Smith's own 28°F hard-freeze dates, about Apr 20 and Oct 11 and the ~174-day span between themNOAA 1991–2020 Climate Normals
- 16 documented contamination sites on the federal record near Fort Smith, the closest Underground Storage Tanks record about 0.4 miles out from the town centreFederal environmental registers
- Fort Smith's boundary and the 883 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~174-day seasonGrowable Ground crop-matching engine
- The ecoregion at Fort Smith's own centroid, the Northwestern Great PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Fort Smith's 883 acres read through its county's SSURGO summaryfrom Big Horn County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Big Horn 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 Big Horn County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Fort Smith's 883 acreswhy one lot differs from the next →
- Which side of Fort Smith you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 883 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.4 miles 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 Fort Smith-wide figureread your own land →
More in Montana
Wider growing context
What grows across MontanaFort Smith sits outside our named growing regions, so Montana as a whole is its closest context here.
Nearby growing guides