Dillon, Montana, sits in USDA hardiness zone 5a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Well-matched crops include cabbage, cranberry, lavender, and collard greens, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
Even in Dillon, 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 Dillon 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 Dillon — soil, climate, flood, and parcel records. How we handle your address.
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Dillon — the short answer
Dillon, Montana: USDA zone 5a, about 141 days between hard freezes, across 1K acres of city.
- 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 29
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~141
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 1K 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 Dillon's average, not your lot's — a low corner or a tree line moves it. Against Dillon's 141-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Dillon
Each reading below is measured for Dillon itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredDillon runs about 141 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
MeasuredDillon 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 Dillon is in
Dillon sits in the Middle Rockies — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at Dillon's own centroid rather than borrowed from Beaverhead County.
What Grows in Dillon
Every plant below cleared Dillon's own zone 5a and its 141-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in Dillon?
For most of the year, no — what changes is which crops still fit the days remaining. 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 29 — 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 Dillon
Closest first, within ~10 miles of Dillon. Listing isn't leaking, and distance isn't exposure.
- TOWN PUMP INC DILLON 1Underground Storage Tanks · 150 ft
- MOUNTAIN VIEW CEMETERY & CITY HALLUnderground Storage Tanks · 300 ft
- TELE COMMUNICATIONS INCUnderground Storage Tanks · 450 ft
- BEAVERHEAD COUNTY HIGH SCHOOLUnderground Storage Tanks · 450 ft
- ABANDONED TANKS OWNERSHIP UNKUnderground Storage Tanks · 500 ft
- QWEST DILLON CENTRAL OFFICEUnderground Storage Tanks · 550 ft
- VIGILANTE ELECTRIC COOPUnderground Storage Tanks · 600 ft
- FORMER HUSKY STATION DILLONUnderground Storage Tanks · 750 ft
- GLENN W HAYDEN RANCHUnderground Storage Tanks · 750 ft
- COUNTY COURTHOUSEUnderground Storage Tanks · 750 ft
- OLD UNION PACIFIC DEPOTUnderground Storage Tanks · 850 ft
- THE MINI INCUnderground Storage Tanks · 950 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Dillon'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 Dillon.
Total Sites
163
within ~10 miles of Dillon
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of Dillon
Severity Distribution
within ~10 miles of Dillon
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Dillon, two things run higher than the national average within ~10 miles of Dillon — CAFO (5 sites) and Nitrate (90 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Dillon
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 Dillon average
Your land is one point inside Dillon
Everything above resolves to Dillon as a whole — one PHZM band and one 28°F frost record, read across 1K 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 Dillon Average
Dillon Average
- ●USDA Zones 5a, averaged across Dillon
- ●One soil character for all of Dillon
- ●Frost dates read at Dillon's scale: May 11 to Sep 29
YOUR Parcel
- ✓Your exact zone, not Dillon's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Dillon
Pull a site-specific report for your exact address in Dillon, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Dillon averages can't show:
We read public map data around Dillon — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Dillon average
How we know this about Dillon
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 Dillon’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 Dillon
When does frost risk typically end in Dillon?
The last hard freeze (28°F) in Dillon 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 Dillon?
The first hard freeze (28°F) in Dillon typically arrives around Sep 29, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 15, so the watching starts about Aug 30 — about 141 days after the spring freeze cleared.
How long is the growing season in Dillon?
Measured between 28°F hard freezes, Dillon sees about 141 frost-free days — roughly May 11 through Sep 29, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 1 to Sep 15, about 106 days.
Is the soil safe to grow vegetables in Dillon?
The federal record around Dillon is a meaningful one — 163 documented sites, mostly Nitrate entries (90), 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 gardeners stretch the season in Dillon?
With about 141 frost-free days between hard freezes, Dillon 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 169 to 197 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 Dillon's scale — its 5a band and its 141-day season. Your yard writes its own version of Dillon'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 Dillon’s own scale
6 of the readings below were taken at Dillon's own scale — its own ~141-day season between 28°F freezes, the 1,215 acres it covers and 163 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Dillon's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Dillon's own 28°F hard-freeze dates, about May 11 and Sep 29 and the ~141-day span between themNOAA 1991–2020 Climate Normals
- 163 documented contamination sites on the federal record near Dillon, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Dillon's boundary and the 1,215 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~141-day seasonGrowable Ground crop-matching engine
- The ecoregion at Dillon's own centroid, the Middle RockiesUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Dillon's 1,215 acres read through its county's SSURGO summaryfrom Beaverhead County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Beaverhead 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 Beaverhead County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Dillon's 1,215 acreswhy one lot differs from the next →
- Which side of Dillon you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,215 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 Dillon-wide figureread your own land →
More in Montana
Wider growing context
What grows across MontanaDillon sits outside our named growing regions, so Montana as a whole is its closest context here.
Nearby growing guides