Monarch, Montana, sits in USDA hardiness zone 4b — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
Well-matched crops include cabbage, cranberry, cilantro, 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 Monarch, 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 Monarch 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 Monarch — soil, climate, flood, and parcel records. How we handle your address.
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Monarch — the short answer
Monarch, Montana: USDA zone 4b, about 136 days between hard freezes, across 514 acres of town.
- USDA zone
- 4b
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 13
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Sep 26
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~136
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 514 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 Monarch's average, not your lot's — a low corner or a tree line moves it. Against Monarch's 136-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Monarch
Each reading below is measured for Monarch itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredMonarch runs about 136 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
MeasuredMonarch 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 Monarch is in
Monarch sits in the Middle Rockies — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at Monarch's own centroid, and it is not what its county reads: Cascade County is mostly Northwestern Glaciated Plains. The wider page above you is answering a different question about different ground.
What Grows in Monarch
Every plant below cleared Monarch's own zone 4b and its 136-day season. Each card opens that plant's Montana profile. How we score.
Is it too late to plant in Monarch?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Apr 15; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 13 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 26 — long-season crops need about 90 days of runway, quick greens only 30. In a season this compact, fast finishers and cold-hardy greens do the late work, and garlic tucked in before the freeze repays you next summer.
What's on the federal record near Monarch
Closest first, within ~10 miles of Monarch. Listing isn't leaking, and distance isn't exposure.
- COUGAR CANYON LODGE & ESCAPEUnderground Storage Tanks · 2300 ft
- MALMSTROM AFB A 7Underground Storage Tanks · 4.0 mi
- MALMSTROM AFB A 6Underground Storage Tanks · 4.0 mi
- MALMSTROM AFB A 8Underground Storage Tanks · 4.0 mi
- MDOT MONARCH MAINTUnderground Storage Tanks · 4.0 mi
- MALMSTROM AFB A 5Underground Storage Tanks · 4.0 mi
- Sunshine MineMining · 7.2 mi
- BELT CREEK CCC CAMPSuperfund · 7.7 mi
- Pride of the WestMining · 9.1 mi
- Marcelline Tunnel No. 2 of LibertyMining · 9.3 mi
- Danny T Tunnel of Liberty MineMining · 9.3 mi
- Iron MountainMining · 9.4 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Monarch'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 Monarch.
Severity Distribution
within ~10 miles of Monarch
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Monarch, Mining runs higher than the national average — 35 sites within ~10 miles of Monarch. That's not a problem with your land — it's information about it.
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 Monarch
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 Monarch average
Your land is one point inside Monarch
Everything above resolves to Monarch as a whole — one PHZM band and one 28°F frost record, read across 514 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 Monarch Average
Monarch Average
- ●USDA Zones 4b, averaged across Monarch
- ●One soil character for all of Monarch
- ●Frost dates read at Monarch's scale: May 13 to Sep 26
YOUR Parcel
- ✓Your exact zone, not Monarch's 4b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Monarch
Pull a site-specific report for your exact address in Monarch, Montana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Monarch averages can't show:
We read public map data around Monarch — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Monarch average
How we know this about Monarch
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 Monarch’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 Monarch
When does frost risk typically end in Monarch?
The last hard freeze (28°F) in Monarch typically lands around May 13, 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 3.
When is the first frost in Monarch?
The first hard freeze (28°F) in Monarch typically arrives around Sep 26, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 12, so the watching starts about Aug 27 — about 136 days after the spring freeze cleared.
How long is the growing season in Monarch?
Measured between 28°F hard freezes, Monarch sees about 136 frost-free days — roughly May 13 through Sep 26, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 3 to Sep 12, about 101 days.
Is the soil safe to grow vegetables in Monarch?
The federal record around Monarch runs heavier than most — 44 documented sites, mostly Mining entries (35), the nearest Underground Storage Tanks record about 0.4 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 Monarch?
With about 136 frost-free days between hard freezes, Monarch 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 164 to 192 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 13 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Monarch's scale — its 4b band and its 136-day season. Your yard writes its own version of Monarch'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 Monarch’s own scale
6 of the readings below were taken at Monarch's own scale — its own ~136-day season between 28°F freezes, the 514 acres it covers and 44 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Monarch's own USDA hardiness band, zones 4bUSDA PHZM 2023
- Monarch's own 28°F hard-freeze dates, about May 13 and Sep 26 and the ~136-day span between themNOAA 1991–2020 Climate Normals
- 44 documented contamination sites on the federal record near Monarch, the closest Underground Storage Tanks record about 0.4 miles out from the town centreFederal environmental registers
- Monarch's boundary and the 514 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4b and a ~136-day seasonGrowable Ground crop-matching engine
- Monarch sits in the Middle Rockies — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Monarch's 514 acres read through its county's SSURGO summaryfrom Cascade County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Cascade 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 Cascade County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Monarch's 514 acreswhy one lot differs from the next →
- Which side of Monarch you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 514 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.4 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 Monarch-wide figureread your own land →