Garfield County, in Montana, sits in USDA hardiness zone 4a — a zone band wide enough that plant choice, not possibility, is the interesting question.
Reliable performers under these conditions include cabbage, cranberry, cilantro, and collard greens; what your own ground favors still comes down to its soil, sun, and drainage.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Garfield County holds more than one microclimate.
Soils and elevations shift across Garfield 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 Garfield County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Garfield County — the short answer
Garfield County, Montana: USDA zone 4a, about 149 days between hard freezes, across 3.0M acres.
- USDA zone
- 4a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 6
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 2
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~149
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 3.0M 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 4a is Garfield County's average, not your lot's — a low corner or a tree line moves it. Against Garfield County's 149-day season, see what your own ground reads.
Heat in Garfield County
Across a year, Garfield County accumulates about 2,051 growing degree days above 50°F, about 381 more than the middle Montana county — ahead of 46 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 Garfield County
Across Garfield County, the ground is predominantly Inceptisols, where Cambeth, Cabbart, and Lonna are the most extensive named soil series. The soil is generally well drained with a silt loam surface. Topsoil pH runs about 7.2–7.9, slightly alkaline. Rainfall drains through hydrologic group C soils.
Soil order
Inceptisols
Drainage
Well drained
Hydric soils
0%
Soil still varies lot by lot — soil types explained.
How the ground varies across Garfield County
Cambeth is the most extensive named soil at 13% of mapped acres, then Cabbart (11%) and Lonna (9%).
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 Garfield County
Each reading below is measured for Garfield 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 Garfield County are well drained, in hydrologic group C — 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 Garfield County runs about pH 7.2–7.9, 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
MeasuredGarfield County runs about 149 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
MeasuredGarfield County 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 Garfield County is in
Garfield County sits in the Northwestern Great Plains — EPA Level III, inside the wider Great Plains. One consistent ecological setting across the whole county.
What Grows in Garfield County
We scored all 1,086 plants against Garfield County's own USDA zone 4a and its own 149-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 Garfield County?
For most of the year, no — what changes is which crops still fit the days remaining. 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 2 — long-season crops need about 90 days of runway, quick greens only 30. In a season this compact, fast finishers and cold-hardy greens do the late work, and garlic tucked in before the freeze repays you next summer.
What gets applied to farmland in Garfield County
USGS estimates 175,713 lb of Glyphosate on Garfield County farmland in 2019, its largest by weight, ahead of 2,4-d (46,846 lb) and Bromoxynil (11,835 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 Garfield County — and how to grow with it.
We checked the federal record across Garfield County — 99 documented sites across 4 of the 9 source types we track.
The most significant on record: 1 Superfund site (none NPL-listed). Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
There's a meaningful federal record across Garfield County — worth a look before you plant food, not a reason to hold back from growing. Proximity to a documented site is information, not a diagnosis of any one yard. A soil test before new food beds is the sensible precaution here, and the map shows exactly which sites sit where, so you can see what's actually near you.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Garfield County
Closest first, across Garfield County. Listing isn't leaking, and distance isn't exposure.
- 18N37E31AB 01Nitrate · 2.6 mi
- 18N38E18AACC01Nitrate · 5.2 mi
- FARMERS UNION OIL CO JORDANUnderground Storage Tanks · 5.3 mi
- PIONEER GARAGE INCUnderground Storage Tanks · 5.4 mi
- GARFIELD CO DIST HIGH SCHOOLBrownfields · 5.5 mi
- 6 DS INCUnderground Storage Tanks · 5.5 mi
- FELLMANS HARDWARE INCUnderground Storage Tanks · 5.5 mi
- MDOT HILLSIDE SECTION HEADQUARTERSUnderground Storage Tanks · 5.6 mi
- LOREN J KIRBYUnderground Storage Tanks · 5.6 mi
- SNOWBELT ANGUS RANCH COUnderground Storage Tanks · 5.6 mi
- JORDAN WILDLIFE STATIONUnderground Storage Tanks · 5.6 mi
- KARLS HELL CREEK MARINAUnderground Storage Tanks · 5.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Garfield 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 Garfield County.
Total Sites
99
across Garfield County
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
across Garfield County
Severity Distribution
across Garfield County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Garfield County, Nitrate runs higher than the national average — 80 sites across Garfield County. 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 Garfield 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 Garfield County average
Your land is one point inside Garfield County
Everything above resolves to Garfield County as a whole — one PHZM band and one county frost record, read across 3.0M 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 Garfield County Average
Garfield County Average
- ●USDA Zones 4a, averaged across Garfield County
- ●One soil character for all of Garfield County
- ●Frost dates read at Garfield County's scale: May 6 to Oct 2
YOUR Parcel
- ✓Your exact zone, not Garfield County's 4a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Garfield County
Pull a site-specific report for your exact address in Garfield County, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Garfield County averages can't show:
We read public map data around Garfield County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Garfield County average
How we know this about Garfield 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 Garfield County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Garfield County
When does frost risk typically end in Garfield County?
The last hard freeze (28°F) in Garfield County 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.
How long is the growing season in Garfield County?
Measured between 28°F hard freezes, Garfield County sees about 149 frost-free days — roughly May 6 through Oct 2, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 27 to Sep 18, about 114 days.
Is the soil safe to grow vegetables in Garfield County?
The federal record around Garfield County is a meaningful one — 99 documented sites, mostly Nitrate entries (80), the nearest Nitrate record about 2.6 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 gardeners stretch the season in Garfield County?
With about 149 frost-free days between hard freezes, Garfield County 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 177 to 205 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 Garfield County's scale — its 4a band and its 149-day season. Your yard writes its own version of Garfield 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 Garfield County’s own scale
8 of the readings below were taken at Garfield County's own scale — its own ~149-day span between 28°F freezes, the 3 most extensive soil series mapped here and 99 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Garfield County's own USDA hardiness band, zones 4aUSDA PHZM 2023
- Garfield County's own 28°F hard-freeze dates and its ~149-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Garfield CountyUSDA NRCS SSURGO
- 99 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Nitrate record about 2.6 miles outFederal environmental registers
- Garfield County's boundary and the 2,992,995 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4a and a ~149-day seasonGrowable Ground crop-matching engine
- Garfield County sitting wholly inside the Northwestern Great PlainsUS EPA Level III Ecoregions
- Which agricultural compounds go onto Garfield 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 Garfield County — the ~149 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 Garfield County's 2,992,995 acreswhy one lot differs from the next →
- Which of those 99 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 Garfield Countyread your own land →