Generally — Most Areas
clematis (zones 4-8) suits most of Montana (3a-6b) — zones 4-6 are in range, and the rest of the state is the exception.
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 clematis against your parcel's actual hardiness, soil, and sun.
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Zone Comparison
Clematis Needs
- USDA Zones: 4-8
- Mature size: 12 ft tall
- 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 4-8)
Plant data: USDA PLANTS Database / Growable Ground plant catalog. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Clematis 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.
Winter standing
Montana runs as cold as USDA zone 3, and no sourced winter-hardiness floor is on record for clematis, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether clematis 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.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: USDA PLANTS Database. 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 clematis survives winter in part of Montana, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Growing degree days
Clematis needs ~2000 GDD (base 50°F) to ripen. The state median runs ~1769 GDD (from PRISM 1991-2020 climate normals), so Montana's typical season runs short on heat — pick a south-facing site and consider season extension.
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.
Clematis in Montana — Quick Answer
- Verdict: Generally — Most Areas
- Plant Zones: 4-8 (USDA PLANTS Database)
- State Zones: 3a-6b (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about May 2 - May 13 to Sep 28 - Oct 7 (NOAA Regional Climate Centers ACIS, 1991-2020)
What Else to Consider for Clematis 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)
What to actually do about these — and the constraints that apply to every Montana grower, not just clematis — is covered on the Montana growing guide.
Where in Montana Clematis Is Zone-Hardy
Clematis is rated for USDA zones 4–8. 53 of Montana’s 56 counties fall inside that band. The coldest that does is Blaine County at zone 4a. 3 counties sit below the plant’s zone 4 floor, where an unprotected plant is relying on snow cover and a mild year. Where you are in Montana decides this one.
Across those 56 counties Montana’s winter-low ladder runs from zone 3b in Daniels County to zone 6a in Sanders County — 2.5 USDA zones of spread, which is 25°F between the two counties’ average coldest night of the year. That is why a statewide hardiness answer is where you start and not where you finish.
The planting window moves with it. Deer Lodge County holds its last hard freeze (28°F) until about Jun 21, while Petroleum County is clear by Apr 25 — 57 days apart. Set clematis out on your county’s date, not the state’s.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. County last-freeze dates: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F killing freeze — earlier than the folk 32°F "last frost". Clematis’s zone 4–8 band: USDA PLANTS / Growable Ground plant database. A parcel report resolves your address’s own zone and frost dates rather than its county’s.
Where in Montana Fits Best
Even within Montana's zones 3a-6b, county microclimates differ enough to change what thrives. These counties carry the closest zone match for clematis (USDA PHZM 2023):
Pollinator + Wildlife Value
Clematis draws honeybees and native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, clematis 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.
Montana Cooperative Extension
For Montana-specific cultivar recommendations, planting calendars, and pest pressure for clematis, the canonical source is Montana State University Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Common Questions About Growing Clematis in Montana
When can I plant Clematis 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 Clematis, 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 Clematis grown in across Montana?
Montana spans USDA hardiness zones 3a-6b (USDA ARS PHZM 2023). Clematis carries a range of zones 4-8, 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). Clematis 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.
Will Clematis actually grow on my specific land in Montana?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores clematis 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 clematis against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Montana clematis averages can't show:
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