Conditional — Some Areas
pansy (zones 6-10) reaches only part of Montana (3a-6b): zone 6 are in range, so where you are in the state decides it.
One zone short — what would close it
Pansy is hardy to zone 6, and the warmest ground in Montana is zone 5 — 1 zone short. Planted in open ground it will not survive a Montana winter. To grow it here, grow pansy in a hoop house or unheated greenhouse — its modeled 1.5-zone lift covers this gap.
A hoop house or unheated greenhouse is the lift this needs. How a greenhouse changes what you can grow →
Zone math from 6-10 (plant) against 3-5 (Montana). Lift modeled by crop_engine.GREENHOUSE_ZONE_MODIFIER_BY_SUBTYPE['hoop_house'] (+1.5 zones) via api/fast_sections.py Unlock Engine v2.
Pansy in Montana — the short answer
Pansy in Montana: hardy in zones 6–10, part sun, against a state median of ~151 frost-free days.
- Plant zones
- 6-10
- Manual horticultural correction (source not retained); NC State Extension and Missouri Botanical Garden, with the remaining rows from other published sources or Growable Ground compilation
- Montana zones
- 3a-6b
- USDA PHZM 2023
- Frost window
- May 2 - May 13 – Sep 28 - Oct 7
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 59 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
- Days to maturity
- 70 days
- Growable Ground Plant Database
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS and university Extension sources — per-field provenance varies and is published with the dataset.
Your yard isn't the whole zone.
Montana spans zones 3a-6b, but your yard sits in exactly one — and slope, tree cover, and cold-air pockets nudge it further. Enter your address and we'll score pansy against your parcel's actual hardiness, soil, and sun.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Montana is not one climate
Montana’s winter-low ladder runs across 56 counties, from zone 3.5 in Daniels County to zone 6 in Sanders County. That is 25°F between the two counties’ average coldest night — the difference between pansy overwintering in the ground and coming under cover.
The middle half of 56 counties runs 4–5 zones, with a median of 4.5 zones — a 2.5-zone span end to end.
Measured across 56 Montana counties. USDA PHZM 2023, per county. Quartiles are order statistics — every figure shown is a value a real county recorded, not an interpolation. Your own site sits somewhere inside this range; a parcel report resolves where.
Where in Montana Fits Best
Pansy is rated for zones 6–10 — a cold floor USDA puts at -10 to 0°F. Against Montana’s 56 counties that band holds in 5 of them, and the line runs at Lake County (zone 6a), the coldest county still inside it.
Below the zone 6 floor
51 counties
- Daniels County · zone 3b
- Roosevelt County · zone 3b
- Sheridan County · zone 3b
3 of 51 shown
Winter cold is the limit here — the same plant works in a container that comes under cover.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. A zone is a 10°F band of average annual extreme minimum temperature, so the floor above is the band the plant's rating denotes, not a single measured kill point. Slope, shelter and cold-air drainage routinely move a site half a zone either way from its county figure — which is the part only your address resolves.
Even within Montana's zones 3a-6b, county microclimates differ enough to change what thrives. These counties carry the closest zone match for pansy (USDA PHZM 2023):
Zone Comparison
Pansy Needs
- USDA Zones: 6-10
- Sun: Part Sun
- Mature size: 9 in tall
- Picking window: ~90 days of harvest
- Drought tolerance: Low
Montana Has
- USDA Zones: 3a-6b
- Last Hard Freeze (28°F): May 2 - May 13
- First Hard Freeze (28°F): Sep 28 - Oct 7
- Annual Rainfall: 10-20 inches
- Common Soils: Sandy loam, Clay, Glacial till
Plant Zone Range (zones 6-10)
Preferred Soil pH
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS, and university Extension sources — per-field provenance varies and is published with the dataset. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Pansy in Montana
The frost window
Across Montana, the last spring hard freeze (28°F) clears between May 2 and May 13, and the first fall hard freeze lands between Sep 28 and Oct 7 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 138-day window you can count on — up to 158 days on a mild site in a kind year. That marks the hard freeze, not the last light frost, so tender transplants usually wait another 2-3 weeks.
When to start the seed
Those dates are when pansy goes out, not when it starts. It is sown under cover about 10 weeks ahead, so counting back from Montana's late-side last freeze of May 13 is what fixes your sowing date — and a yard that clears frost earlier than the state's late date starts earlier still.
Winter standing
Montana runs as cold as USDA zone 3, and no sourced winter-hardiness floor is on record for pansy, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether pansy is a permanent planting or a replant-every-spring crop for you turns on your own zone within Montana; check its hardiness range against that before treating it as long-lived ground.
Timing tuned to sub-state frost dates — Deer Lodge County, not the statewide average.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: Growable Ground Plant Database — frost-free days from FAO ECOCROP, days to harvest from university Extension production guides, and growing-degree-day and chill-hour minimums that are compilation estimates rather than published figures. Your site's own frost dates can run earlier or later than the state range — a parcel report pins them down.
Growing Season Fit
The zone check says pansy survives winter in part of Montana, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Days to maturity
Pansy matures in ~70 days (Growable Ground Plant Database). A typical Montana site has ~151 frost-free days, so plenty of room for a second succession.
Growing degree days
Pansy needs ~500 GDD (base 50°F) to ripen. The state median runs ~1769 GDD (from PRISM 1991-2020 climate normals), so Montana's typical season clears that easily.
GDD and chill-hour figures are computed from PRISM 1991-2020 monthly climate normals; frost-free days from NOAA Regional Climate Centers ACIS, 1991-2020. Each is the state median across its counties (P25/P75 span the within-state spread). Hardiness-zone range is USDA PHZM 2023.
Soil + Drainage Fit
Pansy likes near-neutral soil (pH 5.4-6.5). That's the common-ground band across Montana's sandy loam and clay — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 5.4 and 5.8 — worth knowing before you decide whether a Montana soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Montana site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
Montana soil pH runs about 7.0–7.5, and that sits above pansy's tolerated 5.4–6.5, so the typical Montana parcel needs sulfur to bring it down. SSURGO maps it swinging by full points parcel to parcel, so your map unit, not the state number, decides whether pansy needs lime or sulfur.
Check your parcel → Source: USDA NRCS SSURGO.
Plant pH requirements: FAO ECOCROP and USDA PLANTS, with the remaining rows from other published sources or Growable Ground compilation. Drainage: FAO ECOCROP, with the remaining rows from other published sources or Growable Ground compilation. Montana soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
What Else to Consider for Pansy in Montana
Zone compatibility tells you about winter cold survival — but Montana growers also need to think about:
Very short growing season (60-100 frost-free days)
Low rainfall requires irrigation in most areas
Extreme winter cold (-40F possible)
Growing pansy here specifically
Pansy prefers acidic soil (pH 5.4–6.5), but Montana's soils trend alkaline (SSURGO dominant pH near 7.2) — above its range, iron and other micronutrients become unavailable.
Test your soil and acidify with elemental sulfur toward pansy's 5.4–6.5 range before planting. How to handle it →
What to actually do about these — and the constraints that apply to every Montana grower, not just pansy — is covered on the Montana growing guide.
Timing shifts within Montana
Montana isn't one climate. In Deer Lodge County, the last hard freeze (28°F) holds until about Jun 21 — roughly 47 days later than the recorded state median — so plant pansy to your county's window, not the statewide date.
Pansy needs about 70 days of frost-free season from planting to harvest. 55 of Montana’s 56 counties give it that outright. The tightest that does is Gallatin County at 114 frost-free days — 44 to spare. Below that line you are transplanting or extending the season, not direct-sowing.
Across Montana’s 56 counties the frost-free season runs from 59 days in Deer Lodge County to 170 days in Petroleum County — a spread of 111 days, which is why a single statewide planting date misleads. The median Montana county sees 151 frost-free days, leaving pansy about 81 days of slack on a typical parcel — room for a second sowing where the season runs long.
County last-freeze dates and frost-free day counts: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F freeze (earlier than the folk 32°F "last frost"). Pansy's 70-day requirement: USDA PLANTS / Growable Ground plant database (days to maturity). A parcel report resolves your address's own frost dates.
Pollinator + Wildlife Value
Pansy draws honeybees and native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, pansy can only work that bloom inside Montana's frost window — roughly 151 days, opening after the last 28°F freeze (May 2 - May 13) and closing at the first (Sep 28 - Oct 7), per NOAA Regional Climate Centers ACIS, 1991-2020.
Recommended Pansy Varieties for Montana
Montana publishes no state variety trial for pansy, so we won't invent a "best for Montana" list. Choose types rated to your USDA hardiness zone (3a-6b), and confirm winter survival and drainage against your own parcel.
Montana Cooperative Extension
For Montana-specific cultivar recommendations, planting calendars, and pest pressure for pansy, the canonical source is Montana State University Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Pansy native to Montana?
No — the USDA PLANTS Database lists Pansy as introduced rather than native in the Lower 48, so it is not part of Montana's native flora. It grows here as a garden plant; pairing it with a few Montana natives keeps local pollinators fed too.
Looking for plants that belong here? The Montana growing guide lists USDA-documented natives for the state.
Native-range data: USDA PLANTS Database state-distribution records, accessed 2026-07-01.
Common Questions About Growing Pansy in Montana
When can I plant Pansy in Montana?
Montana's last spring hard freeze (28°F) clears between May 2 and May 13, and the first fall hard freeze lands between Sep 28 and Oct 7 (NOAA Regional Climate Centers ACIS, 1991-2020). No sourced winter-hardiness floor is on record for Pansy, so this page does not state whether it overwinters in Montana and publishes no fall establishment date for it — check its hardiness range against your own zone before treating it as a permanent planting.
What hardiness zone is Pansy grown in across Montana?
Montana spans USDA hardiness zones 3a-6b (USDA ARS PHZM 2023). Pansy carries a range of zones 6-10, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Montana site have?
A typical Montana site sees ~151 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Pansy should be matched against that window, so check whether your local microclimate runs above or below the state average before settling on a planting date. In cooler counties like Deer Lodge, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Pansy native to Montana?
No — the USDA PLANTS Database lists Pansy as introduced rather than native in the Lower 48, so it is not part of Montana's native flora. It grows here as a garden plant; pairing it with a few Montana natives keeps local pollinators fed too.
How should I amend the soil for Pansy in Montana?
Pansy prefers pH 5.4-6.5 and well (dry spells) drainage (Growable Ground Plant Database). That sits in the common-ground band across Montana soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Pansy actually grow on my specific land in Montana?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores pansy against your address's exact soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in Montana
State-level data is a sketch. Your Growable Ground report scores pansy against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Montana pansy averages can't show:
We read public map data around Montana — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Montana pansy average
Explore More
Growing guides for pansy
Explore Montana county by county
Montana carries 56 counties with their own USDA zone — a sample of the growing pages for pansy there:
Where else pansy grows
Pansy's zone band crosses state lines — these are the states closest to Montana in winter climate where it also has a page, plus the far ends of its range. Each one re-answers the question with that state's own record.
More to grow in Montana
Montana has a growing page for 747 plants — a rotating sample of the rest of the shelf.
Analysis by the Growable Ground research team, grounded in USDA PLANTS, USDA NRCS SSURGO, NOAA Climate Normals (1991-2020), and named Cooperative Extension sources. How we know →
Cite this dataset
Kirchick, M. (2026). Growable Ground Plant Database [Data set]. Zenodo. https://doi.org/10.5281/zenodo.21435643
Licensed CC BY-NC 4.0. DOI 10.5281/zenodo.21435643
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