Harlowton, Montana, sits in USDA hardiness zone 4b — a zone band wide enough that plant choice, not possibility, is the interesting question.
Crops well matched to these conditions include cabbage, cranberry, cilantro, and collard greens — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Even in Harlowton, 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 Harlowton 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 Harlowton — soil, climate, flood, and parcel records. How we handle your address.
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Harlowton — the short answer
Harlowton, Montana: USDA zone 4b, about 140 days between hard freezes, across 401 acres of city.
- USDA zone
- 4b
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 10
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Sep 27
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~140
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 401 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 Harlowton's average, not your lot's — a low corner or a tree line moves it. Against Harlowton's 140-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Harlowton
Each reading below is measured for Harlowton itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredHarlowton runs about 140 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
MeasuredHarlowton 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 Harlowton is in
Harlowton sits in the Northwestern Great Plains — EPA Level III, inside the wider Great Plains. That is read at Harlowton's own centroid rather than borrowed from Wheatland County.
What Grows in Harlowton
Every plant below cleared Harlowton's own zone 4b and its 140-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in Harlowton?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Apr 12; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 10 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 27 — 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 Harlowton
Closest first, within ~10 miles of Harlowton. Listing isn't leaking, and distance isn't exposure.
- DEMPSTERS SERVICEUnderground Storage Tanks · 75 ft
- RAYS SPORT & WESTERN WEARUnderground Storage Tanks · 200 ft
- WHEATLAND IMPLEMENT & REPAIRUnderground Storage Tanks · 200 ft
- MDOT HARLOWTONUnderground Storage Tanks · 200 ft
- FASTWAY CONOCO BULK PLANTUnderground Storage Tanks · 200 ft
- MALMSTROM AFB K 4Underground Storage Tanks · 200 ft
- MALMSTROM AFB K 6Underground Storage Tanks · 200 ft
- MALMSTROM AFB K 9Underground Storage Tanks · 200 ft
- MALMSTROM AFB K 11Underground Storage Tanks · 200 ft
- MALMSTROM AFB K 10Underground Storage Tanks · 200 ft
- TOMS BODY SHOPUnderground Storage Tanks · 300 ft
- TOMS BODY SHOPBrownfields · 300 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Harlowton'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 Harlowton.
Total Sites
39
within ~10 miles of Harlowton
Risk Level
Low
Highest-severity
1 mining site (prospects, none worked)
Sources Checked
within ~10 miles of Harlowton
Severity Distribution
within ~10 miles of Harlowton
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Harlowton, Underground Storage Tanks runs higher than the national average — 35 sites within ~10 miles of Harlowton. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Harlowton
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 Harlowton average
Your land is one point inside Harlowton
Everything above resolves to Harlowton as a whole — one PHZM band and one 28°F frost record, read across 401 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 Harlowton Average
Harlowton Average
- ●USDA Zones 4b, averaged across Harlowton
- ●One soil character for all of Harlowton
- ●Frost dates read at Harlowton's scale: May 10 to Sep 27
YOUR Parcel
- ✓Your exact zone, not Harlowton's 4b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Harlowton
Pull a site-specific report for your exact address in Harlowton, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Harlowton averages can't show:
We read public map data around Harlowton — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Harlowton average
How we know this about Harlowton
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 Harlowton’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 Harlowton
When does frost risk typically end in Harlowton?
The last hard freeze (28°F) in Harlowton typically lands around May 10, 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 31.
When is the first frost in Harlowton?
The first hard freeze (28°F) in Harlowton typically arrives around Sep 27, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 13, so the watching starts about Aug 28 — about 140 days after the spring freeze cleared.
How long is the growing season in Harlowton?
Measured between 28°F hard freezes, Harlowton sees about 140 frost-free days — roughly May 10 through Sep 27, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 31 to Sep 13, about 105 days.
Is the soil safe to grow vegetables in Harlowton?
The federal record around Harlowton is light — 39 documented sites across the 9 federal source types we checked, mostly Underground Storage Tanks entries (35), 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 Harlowton?
With about 140 frost-free days between hard freezes, Harlowton 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 168 to 196 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 10 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Harlowton's scale — its 4b band and its 140-day season. Your yard writes its own version of Harlowton'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 Harlowton’s own scale
6 of the readings below were taken at Harlowton's own scale — its own ~140-day season between 28°F freezes, the 401 acres it covers and 39 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Harlowton's own USDA hardiness band, zones 4bUSDA PHZM 2023
- Harlowton's own 28°F hard-freeze dates, about May 10 and Sep 27 and the ~140-day span between themNOAA 1991–2020 Climate Normals
- 39 documented contamination sites on the federal record near Harlowton, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Harlowton's boundary and the 401 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4b and a ~140-day seasonGrowable Ground crop-matching engine
- The ecoregion at Harlowton's own centroid, the Northwestern Great PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Harlowton's 401 acres read through its county's SSURGO summaryfrom Wheatland County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Wheatland 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 Wheatland County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Harlowton's 401 acreswhy one lot differs from the next →
- Which side of Harlowton you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 401 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 Harlowton-wide figureread your own land →
More in Montana
Wider growing context
What grows across MontanaHarlowton sits outside our named growing regions, so Montana as a whole is its closest context here.
Nearby growing guides