Silesia, Montana, sits in USDA hardiness zone 5a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Expect cabbage, cranberry, lavender, and collard greens to be strong candidates here; the deciding factors on any one parcel stay local — soil, sun, and drainage.
Even in Silesia, 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 Silesia 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 Silesia — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Silesia — the short answer
Silesia, Montana: USDA zone 5a, about 163 days between hard freezes, across 1K acres of town.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 27
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 7
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~163
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town 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 Silesia's average, not your lot's — a low corner or a tree line moves it. Against Silesia's 163-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Silesia
Each reading below is measured for Silesia itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredSilesia runs about 163 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
MeasuredSilesia 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 Silesia is in
Silesia sits in the Northwestern Great Plains — EPA Level III, inside the wider Great Plains. That is read at Silesia's own centroid rather than borrowed from Carbon County.
What Grows in Silesia
Every plant below cleared Silesia's own zone 5a and its 163-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in Silesia?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 30; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 27 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 7 — long-season crops need about 90 days of runway, quick greens only 30. As the window narrows, the plantings just get faster — fall brassicas, then greens, then garlic to finish.
What's on the federal record near Silesia
Closest first, within ~10 miles of Silesia. Listing isn't leaking, and distance isn't exposure.
- 03S23E26DACC01Nitrate · 0.6 mi
- JOREEN MILLSUnderground Storage Tanks · 0.7 mi
- 03S23E23DCAB01Nitrate · 0.7 mi
- 03S23E23DAAA01Nitrate · 0.8 mi
- 03S23E26DCCA01Nitrate · 0.9 mi
- 03S23E36CAAA01Nitrate · 1.3 mi
- ROCKVALE TRAVEL PLAZA USTUnderground Storage Tanks · 2.0 mi
- 4S-23E-02bbd01Nitrate · 2.3 mi
- 03S24E07CBBA01Nitrate · 2.8 mi
- 04S23E03BCDA01Nitrate · 2.9 mi
- 03S24E08BBBA01Nitrate · 3.6 mi
- 03S24E08BBBA02Nitrate · 3.7 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Silesia'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 Silesia.
Total Sites
167
within ~10 miles of Silesia
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of Silesia
Severity Distribution
within ~10 miles of Silesia
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Silesia, two things run higher than the national average within ~10 miles of Silesia — CAFO (4 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 Silesia
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 Silesia average
Your land is one point inside Silesia
Everything above resolves to Silesia 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 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 Silesia Average
Silesia Average
- ●USDA Zones 5a, averaged across Silesia
- ●One soil character for all of Silesia
- ●Frost dates read at Silesia's scale: Apr 27 to Oct 7
YOUR Parcel
- ✓Your exact zone, not Silesia's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Silesia
Pull a site-specific report for your exact address in Silesia, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Silesia averages can't show:
We read public map data around Silesia — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Silesia average
How we know this about Silesia
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 Silesia’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 Silesia
When does frost risk typically end in Silesia?
The last hard freeze (28°F) in Silesia typically lands around Apr 27, 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 18.
When is the first frost in Silesia?
The first hard freeze (28°F) in Silesia typically arrives around Oct 7, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 23, so the watching starts about Sep 7 — about 163 days after the spring freeze cleared.
How long is the growing season in Silesia?
Measured between 28°F hard freezes, Silesia sees about 163 frost-free days — roughly Apr 27 through Oct 7, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 18 to Sep 23, about 128 days.
Is the soil safe to grow vegetables in Silesia?
The federal record around Silesia is a meaningful one — 167 documented sites, mostly Nitrate entries (90), the nearest Nitrate record about 0.6 miles 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 Silesia?
From about Sep 7 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 7 (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 7. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Silesia's scale — its 5a band and its 163-day season. Your yard writes its own version of Silesia'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 Silesia’s own scale
6 of the readings below were taken at Silesia's own scale — its own ~163-day season between 28°F freezes, the 1,195 acres it covers and 167 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Silesia's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Silesia's own 28°F hard-freeze dates, about Apr 27 and Oct 7 and the ~163-day span between themNOAA 1991–2020 Climate Normals
- 167 documented contamination sites on the federal record near Silesia, the closest Nitrate record about 0.6 miles out from the town centreFederal environmental registers
- Silesia's boundary and the 1,195 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~163-day seasonGrowable Ground crop-matching engine
- The ecoregion at Silesia's own centroid, the Northwestern Great PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Silesia's 1,195 acres read through its county's SSURGO summaryfrom Carbon County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Carbon 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 Carbon County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Silesia's 1,195 acreswhy one lot differs from the next →
- Which side of Silesia you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,195 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate record about 0.6 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 Silesia-wide figureread your own land →
More in Montana
Wider growing context
What grows across MontanaSilesia sits outside our named growing regions, so Montana as a whole is its closest context here.