De Borgia, Montana, sits in USDA hardiness zone 6a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Among the crops suited to this profile: cabbage, blackberry, california poppy, and collard greens. The site-level story — soil, sun, drainage — decides the rest.
Even in De Borgia, 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 De Borgia 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 De Borgia — soil, climate, flood, and parcel records. How we handle your address.
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De Borgia — the short answer
De Borgia, Montana: USDA zone 6a, about 144 days between hard freezes, across 2K acres of town.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 10
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 1
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~144
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 2K 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 6a is De Borgia's average, not your lot's — a low corner or a tree line moves it. Against De Borgia's 144-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in De Borgia
Each reading below is measured for De Borgia itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredDe Borgia runs about 144 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
MeasuredDe Borgia sits in USDA hardiness zone 6a.
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 De Borgia is in
De Borgia sits in the Northern Rockies — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at De Borgia's own centroid rather than borrowed from Mineral County.
What Grows in De Borgia
Every plant below cleared De Borgia's own zone 6a and its 144-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in De Borgia?
Almost never — the real question is what to plant next. 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 Oct 1 — 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 De Borgia
Closest first, within ~10 miles of De Borgia. Listing isn't leaking, and distance isn't exposure.
- RIVERSIDE ASSOCIATESUnderground Storage Tanks · 1.5 mi
- 18 MILE HOUSEUnderground Storage Tanks · 1.5 mi
- Fox Copper MineMining · 2.9 mi
- True Fissure MineMining · 3.3 mi
- True FissureMining · 3.3 mi
- SILVER EXPRESS EXXONUnderground Storage Tanks · 4.1 mi
- LINCOLNS SILVER DOLLARUnderground Storage Tanks · 4.1 mi
- FORMER MWRR HAUGANUnderground Storage Tanks · 4.1 mi
- Texas MineMining · 4.3 mi
- Valentine MineMining · 4.4 mi
- Rock Island MineMining · 4.4 mi
- Rock IslandMining · 4.4 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from De Borgia'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 De Borgia.
Severity Distribution
within ~10 miles of De Borgia
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around De Borgia, Mining runs higher than the national average — 50 sites within ~10 miles of De Borgia. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Check your specific parcel in De Borgia
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 De Borgia average
Your land is one point inside De Borgia
Everything above resolves to De Borgia as a whole — one PHZM band and one 28°F frost record, read across 2K 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 De Borgia Average
De Borgia Average
- ●USDA Zones 6a, averaged across De Borgia
- ●One soil character for all of De Borgia
- ●Frost dates read at De Borgia's scale: May 10 to Oct 1
YOUR Parcel
- ✓Your exact zone, not De Borgia's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in De Borgia
Pull a site-specific report for your exact address in De Borgia, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that De Borgia averages can't show:
We read public map data around De Borgia — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the De Borgia average
How we know this about De Borgia
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 De Borgia’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 De Borgia
When does frost risk typically end in De Borgia?
The last hard freeze (28°F) in De Borgia 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 De Borgia?
The first hard freeze (28°F) in De Borgia typically arrives around Oct 1, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 17, so the watching starts about Sep 1 — about 144 days after the spring freeze cleared.
How long is the growing season in De Borgia?
Measured between 28°F hard freezes, De Borgia sees about 144 frost-free days — roughly May 10 through Oct 1, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 31 to Sep 17, about 109 days.
Is the soil safe to grow vegetables in De Borgia?
The federal record around De Borgia runs heavier than most — 61 documented sites, mostly Mining entries (50), the nearest Underground Storage Tanks record about 1.5 miles out — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
How do gardeners stretch the season in De Borgia?
With about 144 frost-free days between hard freezes, De Borgia 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 172 to 200 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 De Borgia's scale — its 6a band and its 144-day season. Your yard writes its own version of De Borgia'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 De Borgia’s own scale
6 of the readings below were taken at De Borgia's own scale — its own ~144-day season between 28°F freezes, the 1,752 acres it covers and 61 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- De Borgia's own USDA hardiness band, zones 6aUSDA PHZM 2023
- De Borgia's own 28°F hard-freeze dates, about May 10 and Oct 1 and the ~144-day span between themNOAA 1991–2020 Climate Normals
- 61 documented contamination sites on the federal record near De Borgia, the closest Underground Storage Tanks record about 1.5 miles out from the town centreFederal environmental registers
- De Borgia's boundary and the 1,752 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~144-day seasonGrowable Ground crop-matching engine
- The ecoregion at De Borgia's own centroid, the Northern RockiesUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so De Borgia's 1,752 acres read through its county's SSURGO summaryfrom Mineral County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Mineral 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 Mineral County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among De Borgia's 1,752 acreswhy one lot differs from the next →
- Which side of De Borgia you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,752 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 1.5 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 De Borgia-wide figureread your own land →
More in Montana
Wider growing context
What grows across MontanaDe Borgia sits outside our named growing regions, so Montana as a whole is its closest context here.
Nearby growing guides