Broadwater County, in Montana, sits in USDA hardiness zone 4b — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Among the crops suited to this profile: cabbage, cranberry, turkish rocket, and collard greens. The site-level story — soil, sun, drainage — decides the rest.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Broadwater County holds more than one microclimate.
Soils and elevations shift across Broadwater County, so your frost dates and drainage aren't the county average. 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 Broadwater County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Broadwater County — the short answer
Broadwater County, Montana: USDA zone 4b, about 161 days between hard freezes, across 763K acres.
- USDA zone
- 4b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 29
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 7
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~161
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 763K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 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 4b is Broadwater County's average, not your lot's — a low corner or a tree line moves it. Against Broadwater County's 161-day season, see what your own ground reads.
Heat in Broadwater County
Across a year, Broadwater County accumulates about 1,760 growing degree days above 50°F, about 90 more than the middle Montana county — ahead of 29 of Montana’s 56 counties. Degree days are the heat a crop actually gets to work with — more of them is more room to ripen a long-season crop before the freeze closes the window.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in Broadwater County
Across Broadwater County, the ground is predominantly Mollisols, where Musselshell, Amesha, and Crago are the most extensive named soil series. The soil is generally well drained with a loam surface. Topsoil pH runs about 6.7–7.9, neutral. Rainfall drains through hydrologic group B soils.
Soil order
Mollisols
Drainage
Well drained
Hydric soils
1%
Soil still varies lot by lot — soil types explained.
How the ground varies across Broadwater County
The USDA soil survey maps 55% of Broadwater County as well drained — but another 5% drains differently: 3% somewhat poorly drained, 1% poorly drained.
Musselshell is the most extensive named soil at 6% of mapped acres, then Amesha (6%) and Crago (4%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in Broadwater County
Each reading below is measured for Broadwater County itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across Broadwater County are well drained, in hydrologic group B — ground that drains quickly.
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
MeasuredTopsoil across Broadwater County runs about pH 6.7–7.9, on the alkaline side.
Many vegetables cope, but acid-lovers like blueberries struggle, and iron and manganese lock up above about pH 7.5 — leaves yellow between the veins even in rich soil.
Elemental sulfur and generous organic matter lower pH slowly for the beds that need it; test first so you add only what the soil actually calls for.
USDA NRCS SSURGO
Season length
MeasuredBroadwater County runs about 161 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
MeasuredBroadwater County sits in USDA hardiness zone 4b.
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 Broadwater County is in
Broadwater County sits in the Middle Rockies — EPA Level III, inside the wider Northwestern Forested Mountains. One consistent ecological setting across the whole county.
What Grows in Broadwater County
We scored all 1,086 plants against Broadwater County's own USDA zone 4b and its own 161-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's Montana profile.
Is it too late to plant in Broadwater County?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Apr 1; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 29 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 7 — long-season crops need about 90 days of runway, quick greens only 30. The tail of the season still works: sixty-day crops into late summer, quick greens after, garlic last of all.
What gets applied to farmland in Broadwater County
USGS estimates 76,428 lb of Glyphosate on Broadwater County farmland in 2019, its largest by weight, ahead of 2,4-d (34,186 lb) and Bromoxynil (4,195 lb).
Farmland across the whole county, not any one lot. Check your address for the site-by-site record.
Safe to Grow Here?
What the federal record shows across Broadwater County — and how to grow with it.
We checked the federal record across Broadwater County — 410 documented sites across 6 of the 9 source types we track.
The most significant on record: 3 Toxics Release Inventory facilities. Active industrial facilities reporting chemical releases to air, water, and land.
Broadwater County carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Broadwater County
Closest first, across Broadwater County. Listing isn't leaking, and distance isn't exposure.
- 07N02E29CA 02Nitrate · 2400 ft
- 07N02E29CABC01Nitrate · 0.5 mi
- 07N02E33ABCD01Nitrate · 0.8 mi
- RY TIMBERBrownfields · 0.9 mi
- TOWNSEND TIMBER INDUSTRIESUnderground Storage Tanks · 0.9 mi
- BROADWATER HEALTH CENTERUnderground Storage Tanks · 1.1 mi
- CENEX SOIL SERVICE CENTER TOWNSENDUnderground Storage Tanks · 1.1 mi
- BROADWATER COUNTY SHOPUnderground Storage Tanks · 1.1 mi
- SILOS CAMPGROUND INCUnderground Storage Tanks · 1.1 mi
- ZIPPS TIRESUnderground Storage Tanks · 1.1 mi
- TOWNSEND STARUnderground Storage Tanks · 1.1 mi
- GROVER EXXONUnderground Storage Tanks · 1.1 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Broadwater County'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 Broadwater County.
Total Sites
410
across Broadwater County
Risk Level
High
Highest-severity
3 Toxics Release Inventory facilities
Sources Checked
across Broadwater County
Severity Distribution
across Broadwater County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Broadwater County, two things run higher than the national average across Broadwater County — Mining (195 sites) and Nitrate (146 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Broadwater County
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 Broadwater County average
Your land is one point inside Broadwater County
Everything above resolves to Broadwater County as a whole — one PHZM band and one county frost record, read across 763K 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 county 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 county average.
Your Lot vs the Broadwater County Average
Broadwater County Average
- ●USDA Zones 4b, averaged across Broadwater County
- ●One soil character for all of Broadwater County
- ●Frost dates read at Broadwater County's scale: Apr 29 to Oct 7
YOUR Parcel
- ✓Your exact zone, not Broadwater County's 4b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Broadwater County
Pull a site-specific report for your exact address in Broadwater County, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Broadwater County averages can't show:
We read public map data around Broadwater County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Broadwater County average
How we know this about Broadwater County
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where Broadwater County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Broadwater County
When does frost risk typically end in Broadwater County?
The last hard freeze (28°F) in Broadwater County typically lands around Apr 29, 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 20.
How long is the growing season in Broadwater County?
Measured between 28°F hard freezes, Broadwater County sees about 161 frost-free days — roughly Apr 29 through Oct 7, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 20 to Sep 23, about 126 days.
Is the soil safe to grow vegetables in Broadwater County?
The federal record around Broadwater County runs heavier than most — 410 documented sites, mostly Mining entries (195), the nearest Nitrate record about 0.5 miles out — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
Everything above is measured at Broadwater County's scale — its 4b band and its 161-day season. Your yard writes its own version of Broadwater County's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Montana's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Broadwater County’s own scale
8 of the readings below were taken at Broadwater County's own scale — its own ~161-day span between 28°F freezes, the 3 most extensive soil series mapped here and 410 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Broadwater County's own USDA hardiness band, zones 4bUSDA PHZM 2023
- Broadwater County's own 28°F hard-freeze dates and its ~161-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Broadwater CountyUSDA NRCS SSURGO
- 410 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Nitrate record about 0.5 miles outFederal environmental registers
- Broadwater County's boundary and the 763,109 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4b and a ~161-day seasonGrowable Ground crop-matching engine
- Broadwater County sitting wholly inside the Middle RockiesUS EPA Level III Ecoregions
- Which agricultural compounds go onto Broadwater County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Montana grower plans around — written at state scale, so they stay on the state guidefrom Montana
What this page can’t tell you
- How the season shifts across Broadwater County — the ~161 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Broadwater County's 763,109 acreswhy one lot differs from the next →
- Which of those 410 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over Broadwater Countyread your own land →