Fromberg, Montana, sits in USDA hardiness zone 5a — a zone band wide enough that plant choice, not possibility, is the interesting question.
Reliable performers under these conditions include cabbage, cranberry, lavender, and collard greens; what your own ground favors still comes down to its soil, sun, and drainage.
Even in Fromberg, 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 Fromberg 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 Fromberg — soil, climate, flood, and parcel records. How we handle your address.
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Fromberg — the short answer
Fromberg, Montana: USDA zone 5a, about 160 days between hard freezes, across 284 acres of town.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 30
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 7
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~160
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 284 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 Fromberg's average, not your lot's — a low corner or a tree line moves it. Against Fromberg's 160-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Fromberg
Each reading below is measured for Fromberg itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredFromberg runs about 160 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
MeasuredFromberg 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 Fromberg is in
Fromberg sits in the Northwestern Great Plains — EPA Level III, inside the wider Great Plains. That is read at Fromberg's own centroid rather than borrowed from Carbon County.
What Grows in Fromberg
Every plant below cleared Fromberg's own zone 5a and its 160-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in Fromberg?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Apr 2; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 30 (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. 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 Fromberg
Closest first, within ~10 miles of Fromberg. Listing isn't leaking, and distance isn't exposure.
- FORMER HUSKY STATION FROMBERGUnderground Storage Tanks · 1200 ft
- BN FROMBERGUnderground Storage Tanks · 1500 ft
- JOE YATES AUTO SALES USTUnderground Storage Tanks · 2000 ft
- 05S23E17DCCA01Nitrate · 2400 ft
- 05S23E10AABB01Nitrate · 2.5 mi
- 05S23E31ACAD01Nitrate · 2.8 mi
- 06S23E03BACA01Nitrate · 3.3 mi
- 04S23E31ADCD01Nitrate · 3.6 mi
- 06S23E04CADC01Nitrate · 3.9 mi
- 04S23E29CCCB01Nitrate · 4.1 mi
- TOWN & COUNTRY SUPPLY EDGARUnderground Storage Tanks · 4.9 mi
- 06S23E08DBDB01Nitrate · 5.0 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Fromberg'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 Fromberg.
Total Sites
85
within ~10 miles of Fromberg
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of Fromberg
Severity Distribution
within ~10 miles of Fromberg
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Fromberg, Nitrate runs higher than the national average — 54 sites within ~10 miles of Fromberg. 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 Fromberg
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 Fromberg average
Your land is one point inside Fromberg
Everything above resolves to Fromberg as a whole — one PHZM band and one 28°F frost record, read across 284 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 Fromberg Average
Fromberg Average
- ●USDA Zones 5a, averaged across Fromberg
- ●One soil character for all of Fromberg
- ●Frost dates read at Fromberg's scale: Apr 30 to Oct 7
YOUR Parcel
- ✓Your exact zone, not Fromberg's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Fromberg
Pull a site-specific report for your exact address in Fromberg, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Fromberg averages can't show:
We read public map data around Fromberg — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Fromberg average
How we know this about Fromberg
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 Fromberg’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 Fromberg
When does frost risk typically end in Fromberg?
The last hard freeze (28°F) in Fromberg typically lands around Apr 30, 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 21.
When is the first frost in Fromberg?
The first hard freeze (28°F) in Fromberg typically arrives around Oct 7, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 23, so the watching starts about Sep 7 — about 160 days after the spring freeze cleared.
How long is the growing season in Fromberg?
Measured between 28°F hard freezes, Fromberg sees about 160 frost-free days — roughly Apr 30 through Oct 7, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 21 to Sep 23, about 125 days.
Is the soil safe to grow vegetables in Fromberg?
The federal record around Fromberg is a meaningful one — 85 documented sites, mostly Nitrate entries (54), the nearest Underground Storage Tanks record about 0.2 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 Fromberg?
From about Sep 7 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 7 (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 7. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Fromberg's scale — its 5a band and its 160-day season. Your yard writes its own version of Fromberg'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 Fromberg’s own scale
6 of the readings below were taken at Fromberg's own scale — its own ~160-day season between 28°F freezes, the 284 acres it covers and 85 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Fromberg's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Fromberg's own 28°F hard-freeze dates, about Apr 30 and Oct 7 and the ~160-day span between themNOAA 1991–2020 Climate Normals
- 85 documented contamination sites on the federal record near Fromberg, the closest Underground Storage Tanks record about 0.2 miles out from the town centreFederal environmental registers
- Fromberg's boundary and the 284 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~160-day seasonGrowable Ground crop-matching engine
- The ecoregion at Fromberg's own centroid, the Northwestern Great PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Fromberg's 284 acres read through its county's SSURGO summaryfrom Carbon County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Carbon 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 Carbon County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Fromberg's 284 acreswhy one lot differs from the next →
- Which side of Fromberg you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 284 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.2 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 Fromberg-wide figureread your own land →
More in Montana
Wider growing context
What grows across MontanaFromberg sits outside our named growing regions, so Montana as a whole is its closest context here.