Roundup, 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.
These conditions suit cabbage, cranberry, turkish rocket, and collard greens — a starting list any specific site will trim or extend with its own soil, sun, and drainage.
Even in Roundup, 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 Roundup 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 Roundup — soil, climate, flood, and parcel records. How we handle your address.
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Roundup — the short answer
Roundup, Montana: USDA zone 4b, about 159 days between hard freezes, across 828 acres of city.
- USDA zone
- 4b
- 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 6
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~159
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 828 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 4b is Roundup's average, not your lot's — a low corner or a tree line moves it. Against Roundup's 159-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Roundup
Each reading below is measured for Roundup itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredRoundup runs about 159 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
MeasuredRoundup 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 Roundup is in
Roundup sits in the Northwestern Great Plains — EPA Level III, inside the wider Great Plains. That is read at Roundup's own centroid rather than borrowed from Musselshell County.
What Grows in Roundup
Every plant below cleared Roundup's own zone 4b and its 159-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in Roundup?
Almost never — the real question is what to plant next. 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 6 — 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's on the federal record near Roundup
Closest first, within ~10 miles of Roundup. Listing isn't leaking, and distance isn't exposure.
- BARTOWSUnderground Storage Tanks · 250 ft
- J & W BACKHOE INCUnderground Storage Tanks · 350 ft
- CONOCO CONVENIENCE CENTERUnderground Storage Tanks · 600 ft
- GETTER TRUCKING INC ROUNDUPUnderground Storage Tanks · 650 ft
- MUSSELSHELL COUNTY SHERIFF DEPTUnderground Storage Tanks · 750 ft
- HALLIBURTON COUnderground Storage Tanks · 950 ft
- FORMER MWRR ROUNDUPUnderground Storage Tanks · 950 ft
- ALBRIGHT FLYING INCUnderground Storage Tanks · 950 ft
- MDOT ROUNDUP SITEUnderground Storage Tanks · 950 ft
- ROUNDUP BEACON MICROWAVE SITEUnderground Storage Tanks · 950 ft
- BLM-ROUNDUP LANDFILLSuperfund · 1100 ft
- LAWRENCE SEALEY MAIN STUnderground Storage Tanks · 1300 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Roundup'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 Roundup.
Total Sites
81
within ~10 miles of Roundup
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of Roundup
Severity Distribution
within ~10 miles of Roundup
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Roundup, Nitrate runs higher than the national average — 40 sites within ~10 miles of Roundup. 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 Roundup
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 Roundup average
Your land is one point inside Roundup
Everything above resolves to Roundup as a whole — one PHZM band and one 28°F frost record, read across 828 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 city 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 Roundup Average
Roundup Average
- ●USDA Zones 4b, averaged across Roundup
- ●One soil character for all of Roundup
- ●Frost dates read at Roundup's scale: Apr 30 to Oct 6
YOUR Parcel
- ✓Your exact zone, not Roundup's 4b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Roundup
Pull a site-specific report for your exact address in Roundup, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Roundup averages can't show:
We read public map data around Roundup — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Roundup average
How we know this about Roundup
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Roundup’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 city grain anywhere on this page — there is no city-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 Roundup
When does frost risk typically end in Roundup?
The last hard freeze (28°F) in Roundup 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 Roundup?
The first hard freeze (28°F) in Roundup typically arrives around Oct 6, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 22, so the watching starts about Sep 6 — about 159 days after the spring freeze cleared.
How long is the growing season in Roundup?
Measured between 28°F hard freezes, Roundup sees about 159 frost-free days — roughly Apr 30 through Oct 6, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 21 to Sep 22, about 124 days.
Is the soil safe to grow vegetables in Roundup?
The federal record around Roundup is a meaningful one — 81 documented sites, mostly Nitrate entries (40), the nearest Underground Storage Tanks record under a tenth of a mile 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 Roundup?
From about Sep 6 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 6 (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 6. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Roundup's scale — its 4b band and its 159-day season. Your yard writes its own version of Roundup'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 Roundup’s own scale
6 of the readings below were taken at Roundup's own scale — its own ~159-day season between 28°F freezes, the 828 acres it covers and 81 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Roundup's own USDA hardiness band, zones 4bUSDA PHZM 2023
- Roundup's own 28°F hard-freeze dates, about Apr 30 and Oct 6 and the ~159-day span between themNOAA 1991–2020 Climate Normals
- 81 documented contamination sites on the federal record near Roundup, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Roundup's boundary and the 828 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4b and a ~159-day seasonGrowable Ground crop-matching engine
- The ecoregion at Roundup's own centroid, the Northwestern Great PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Roundup's 828 acres read through its county's SSURGO summaryfrom Musselshell County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Musselshell 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 Musselshell County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Roundup's 828 acreswhy one lot differs from the next →
- Which side of Roundup you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 828 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 Roundup-wide figureread your own land →
More in Montana
Wider growing context
What grows across MontanaRoundup sits outside our named growing regions, so Montana as a whole is its closest context here.
Nearby growing guides