Opheim, Montana, sits in USDA hardiness zone 4a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Expect cabbage, cranberry, cilantro, and collard greens to be strong candidates here; the deciding factors on any one parcel stay local — soil, sun, and drainage.
Even in Opheim, 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 Opheim 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 Opheim — soil, climate, flood, and parcel records. How we handle your address.
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Opheim — the short answer
Opheim, Montana: USDA zone 4a, about 137 days between hard freezes, across 134 acres of town.
- USDA zone
- 4a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 14
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Sep 28
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~137
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 134 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 4a is Opheim's average, not your lot's — a low corner or a tree line moves it. Against Opheim's 137-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Opheim
Each reading below is measured for Opheim itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredOpheim runs about 137 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
MeasuredOpheim 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 Opheim is in
Opheim sits in the Northwestern Glaciated Plains — EPA Level III, inside the wider Great Plains. That is read at Opheim's own centroid rather than borrowed from Valley County.
What Grows in Opheim
Every plant below cleared Opheim's own zone 4a and its 137-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in Opheim?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Apr 16; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 14 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 28 — long-season crops need about 90 days of runway, quick greens only 30. Even here the calendar’s edges hold value: thirty-day greens late in the window, then garlic and a rested bed for spring.
What's on the federal record near Opheim
Closest first, within ~10 miles of Opheim. Listing isn't leaking, and distance isn't exposure.
- BN OPHEIM DEPOTUnderground Storage Tanks · 350 ft
- OLD FARMERS UNION GAS STATION SWUnderground Storage Tanks · 500 ft
- PRO COOP OPHEIMUnderground Storage Tanks · 600 ft
- MDOT OPHEIM SITEUnderground Storage Tanks · 650 ft
- OPHEIM AIR FORCE STATIONUnderground Storage Tanks · 650 ft
- PANKRATZ FARMS INC OPHEIMUnderground Storage Tanks · 650 ft
- FORMER GAS STATION OPHEIMUnderground Storage Tanks · 650 ft
- 36N41E19CBCD01Nitrate · 650 ft
- 36N40E22BCDD01Nitrate · 3.0 mi
- 36N42E30CA 01Nitrate · 6.1 mi
- BN GLENTANA DEPOTUnderground Storage Tanks · 7.2 mi
- 36N39E26AAB 01Nitrate · 7.4 mi
1 more site is on the record inside the same radius. See them on the map
Measured from Opheim'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 Opheim.
Severity Distribution
within ~10 miles of Opheim
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.
Check your specific parcel in Opheim
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 Opheim average
Your land is one point inside Opheim
Everything above resolves to Opheim as a whole — one PHZM band and one 28°F frost record, read across 134 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 Opheim Average
Opheim Average
- ●USDA Zones 4a, averaged across Opheim
- ●One soil character for all of Opheim
- ●Frost dates read at Opheim's scale: May 14 to Sep 28
YOUR Parcel
- ✓Your exact zone, not Opheim's 4a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Opheim
Pull a site-specific report for your exact address in Opheim, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Opheim averages can't show:
We read public map data around Opheim — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Opheim average
How we know this about Opheim
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 Opheim’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 Opheim
When does frost risk typically end in Opheim?
The last hard freeze (28°F) in Opheim typically lands around May 14, 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 Jun 4.
When is the first frost in Opheim?
The first hard freeze (28°F) in Opheim typically arrives around Sep 28, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 14, so the watching starts about Aug 29 — about 137 days after the spring freeze cleared.
How long is the growing season in Opheim?
Measured between 28°F hard freezes, Opheim sees about 137 frost-free days — roughly May 14 through Sep 28, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 4 to Sep 14, about 102 days.
Is the soil safe to grow vegetables in Opheim?
The federal record around Opheim is light — 18 documented sites across the 9 federal source types we checked, mostly Nitrate entries (10), the nearest Underground Storage Tanks record under a tenth of a mile out — and proximity to a documented site is information, not a diagnosis of any one yard. Growing food here starts from a strong position; a soil test before new food beds settles any site-specific question.
How do gardeners stretch the season in Opheim?
With about 137 frost-free days between hard freezes, Opheim 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 165 to 193 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 14 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Opheim's scale — its 4a band and its 137-day season. Your yard writes its own version of Opheim'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 Opheim’s own scale
6 of the readings below were taken at Opheim's own scale — its own ~137-day season between 28°F freezes, the 134 acres it covers and 18 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Opheim's own USDA hardiness band, zones 4aUSDA PHZM 2023
- Opheim's own 28°F hard-freeze dates, about May 14 and Sep 28 and the ~137-day span between themNOAA 1991–2020 Climate Normals
- 18 documented contamination sites on the federal record near Opheim, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Opheim's boundary and the 134 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4a and a ~137-day seasonGrowable Ground crop-matching engine
- The ecoregion at Opheim's own centroid, the Northwestern Glaciated PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Opheim's 134 acres read through its county's SSURGO summaryfrom Valley County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Valley 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 Valley County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Opheim's 134 acreswhy one lot differs from the next →
- Which side of Opheim you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 134 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 Opheim-wide figureread your own land →
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