Trego, Montana, sits in USDA hardiness zone 5a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Among the crops suited to this profile: cabbage, cranberry, lavender, and collard greens. The site-level story — soil, sun, drainage — decides the rest.
Even in Trego, 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 Trego 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 Trego — soil, climate, flood, and parcel records. How we handle your address.
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Trego — the short answer
Trego, Montana: USDA zone 5a, about 135 days between hard freezes, across 34K acres of town.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 11
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Sep 23
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~135
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 34K 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 Trego's average, not your lot's — a low corner or a tree line moves it. Against Trego's 135-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Trego
Each reading below is measured for Trego itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredTrego runs about 135 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
MeasuredTrego 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 Trego is in
Trego sits in the Northern Rockies — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at Trego's own centroid rather than borrowed from Lincoln County.
What Grows in Trego
Every plant below cleared Trego's own zone 5a and its 135-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in Trego?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Apr 13; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 11 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 23 — long-season crops need about 90 days of runway, quick greens only 30. Short seasons reward decisiveness — quick-maturing varieties late, hardy greens under cover, and next year’s garlic in the ground before it closes.
What's on the federal record near Trego
Closest first, within ~10 miles of Trego. Listing isn't leaking, and distance isn't exposure.
- TREGO SCHOOL DIST 53Underground Storage Tanks · 4.3 mi
- ANT FLAT WORK CENTERUnderground Storage Tanks · 4.3 mi
- THE TREGO GENERAL STORE INCUnderground Storage Tanks · 4.5 mi
- FORTINE MERCANTILE US 93Underground Storage Tanks · 6.7 mi
- FORTINE MERCANTILE MAIN STUnderground Storage Tanks · 7.1 mi
- MURPHY LAKE RANGER STATIONUnderground Storage Tanks · 7.1 mi
- FRED W & MARGUERIT TITCHBOURNEUnderground Storage Tanks · 7.1 mi
- PLUM CREEK TIMBER CO FORTINEUnderground Storage Tanks · 7.1 mi
- 35N25W31CA 01Nitrate · 7.1 mi
- BN PINKHAM MOUNTAIN COMP 29Underground Storage Tanks · 7.3 mi
- BN TWIN MEADOWS PRINT 332 COMP 21Underground Storage Tanks · 7.3 mi
- 35N26W25CA 01Nitrate · 7.8 mi
5 more sites are on the record inside the same radius. See them on the map
Measured from Trego'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 Trego.
Severity Distribution
within ~10 miles of Trego
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
Check your specific parcel in Trego
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 Trego average
Your land is one point inside Trego
Everything above resolves to Trego as a whole — one PHZM band and one 28°F frost record, read across 34K 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 Trego Average
Trego Average
- ●USDA Zones 5a, averaged across Trego
- ●One soil character for all of Trego
- ●Frost dates read at Trego's scale: May 11 to Sep 23
YOUR Parcel
- ✓Your exact zone, not Trego's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Trego
Pull a site-specific report for your exact address in Trego, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Trego averages can't show:
We read public map data around Trego — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Trego average
How we know this about Trego
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 Trego’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 Trego
When does frost risk typically end in Trego?
The last hard freeze (28°F) in Trego typically lands around May 11, 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 1.
When is the first frost in Trego?
The first hard freeze (28°F) in Trego typically arrives around Sep 23, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 9, so the watching starts about Aug 24 — about 135 days after the spring freeze cleared.
How long is the growing season in Trego?
Measured between 28°F hard freezes, Trego sees about 135 frost-free days — roughly May 11 through Sep 23, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 1 to Sep 9, about 100 days.
Is the soil safe to grow vegetables in Trego?
The federal record around Trego is light — 22 documented sites across the 9 federal source types we checked, mostly Underground Storage Tanks entries (11), the nearest Underground Storage Tanks record about 4.3 miles 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 Trego?
With about 135 frost-free days between hard freezes, Trego 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 163 to 191 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 11 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Trego's scale — its 5a band and its 135-day season. Your yard writes its own version of Trego'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 Trego’s own scale
6 of the readings below were taken at Trego's own scale — its own ~135-day season between 28°F freezes, the 34,499 acres it covers and 22 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Trego's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Trego's own 28°F hard-freeze dates, about May 11 and Sep 23 and the ~135-day span between themNOAA 1991–2020 Climate Normals
- 22 documented contamination sites on the federal record near Trego, the closest Underground Storage Tanks record about 4.3 miles out from the town centreFederal environmental registers
- Trego's boundary and the 34,499 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~135-day seasonGrowable Ground crop-matching engine
- The ecoregion at Trego's own centroid, the Northern RockiesUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Trego's 34,499 acres read through its county's SSURGO summaryfrom Lincoln County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Lincoln 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 Lincoln County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Trego's 34,499 acreswhy one lot differs from the next →
- Which side of Trego you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 34,499 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 4.3 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 Trego-wide figureread your own land →
More in Montana
Wider growing context
What grows across MontanaTrego sits outside our named growing regions, so Montana as a whole is its closest context here.
Nearby growing guides