Generally — Most Areas
ranunculus (zones 8-10) suits most of Oregon (5a-10a) — zones 8-10 are in range, and the rest of the state is the exception.
Ranunculus in Oregon — the short answer
Ranunculus in Oregon: hardy in zones 8–10, part sun, against a state median of ~213 frost-free days.
- Plant zones
- 8-10
- 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
- Oregon zones
- 5a-10a
- USDA PHZM 2023
- Frost window
- Feb 25 - Apr 26 – Oct 19 - Nov 26
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 86 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
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.
Oregon spans zones 5a-10a, but your yard has its own microclimate — slope, trees, and low spots shift frost and sun across a single parcel. Enter your address and we'll score ranunculus against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Oregon is not one climate
A single Oregon answer averages 36 counties whose growing seasons are 222 days apart — from 86 frost-free days in Klamath County to 308 in Lincoln County. Which end of that your land sits nearer changes what ranunculus can finish before the first hard freeze.
The middle half of 36 counties runs 165–274 days, with a median of 212 days — a 222-day span end to end.
Measured across 36 Oregon counties. NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze. 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 Oregon Fits Best
Ranunculus is rated for zones 8–10 — a cold floor USDA puts at 10 to 20°F. Against Oregon’s 36 counties that band holds in 18 of them, and the line runs at Clackamas County (zone 8a), the coldest county still inside it.
Inside zones 8–10
18 counties
- Josephine County · zone 8a
- Marion County · zone 8a
- Benton County · zone 8b
3 of 18 shown
Below the zone 8 floor
18 counties
- Klamath County · zone 6a
- Baker County · zone 6b
- Crook County · zone 6b
3 of 18 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 Oregon's zones 5a-10a, county microclimates differ enough to change what thrives. These counties carry the closest zone match for ranunculus (USDA PHZM 2023):
Zone Comparison
Ranunculus Needs
- USDA Zones: 8-10
- Sun: Part Sun
- Mature size: 1.5 ft tall
- Picking window: ~30 days of harvest
- Drought tolerance: Low
Oregon Has
- USDA Zones: 5a-10a
- Last Hard Freeze (28°F): Feb 25 - Apr 26
- First Hard Freeze (28°F): Oct 19 - Nov 26
- Annual Rainfall: 8-90 inches
- Common Soils: Volcanic, Silt loam (Willamette), Sandy loam
Plant Zone Range (zones 8-10)
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 Ranunculus in Oregon
The frost window
Across Oregon, the last spring hard freeze (28°F) clears between Feb 25 and Apr 26, and the first fall hard freeze lands between Oct 19 and Nov 26 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 176-day window you can count on — up to 274 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.
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.
What Else to Consider for Ranunculus in Oregon
Zone compatibility tells you about winter cold survival — but Oregon growers also need to think about:
West side: excessive rain and overcast skies reduce sun for warm-season crops
East side: arid conditions (8-15 inches rainfall) require irrigation
Slug pressure is extreme in western Oregon
Mountain areas have very short seasons (60-90 frost-free days)
What to actually do about these — and the constraints that apply to every Oregon grower, not just ranunculus — is covered on the Oregon growing guide.
Where in Oregon Ranunculus Is Zone-Hardy
Ranunculus is rated for USDA zones 8–10. 18 of Oregon’s 36 counties fall inside that band. The coldest that does is Clackamas County at zone 8a. 18 counties sit below the plant’s zone 8 floor, where an unprotected plant is relying on snow cover and a mild year. Where you are in Oregon decides this one.
Across those 36 counties Oregon’s winter-low ladder runs from zone 6a in Klamath County to zone 9b in Curry County — 3.5 USDA zones of spread, which is 35°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. Klamath County holds its last hard freeze (28°F) until about Jun 9, while Lincoln County is clear by Feb 3 — 126 days apart. Set ranunculus 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". Ranunculus’s zone 8–10 band: USDA PLANTS / Growable Ground plant database. A parcel report resolves your address’s own zone and frost dates rather than its county’s.
Pollinator + Wildlife Value
Ranunculus draws honeybees and native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, ranunculus can only work that bloom inside Oregon's frost window — roughly 213 days, opening after the last 28°F freeze (Feb 25 - Apr 26) and closing at the first (Oct 19 - Nov 26), per NOAA Regional Climate Centers ACIS, 1991-2020.
Oregon Cooperative Extension
For Oregon-specific cultivar recommendations, planting calendars, and pest pressure for ranunculus, the canonical source is OSU Extension Service. Their fact sheets carry the local trial data we can't generalize across 50 states.
Common Questions About Growing Ranunculus in Oregon
When can I plant Ranunculus in Oregon?
Oregon's last spring hard freeze (28°F) clears between Feb 25 and Apr 26, and the first fall hard freeze lands between Oct 19 and Nov 26 (NOAA Regional Climate Centers ACIS, 1991-2020). Time outdoor planting to after the last hard freeze for your specific site — a further two to three weeks for anything tender — and count back from those dates for transplant scheduling.
What hardiness zone is Ranunculus grown in across Oregon?
Oregon spans USDA hardiness zones 5a-10a (USDA ARS PHZM 2023). Ranunculus carries a range of zones 8-10, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Oregon site have?
A typical Oregon site sees ~213 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Ranunculus 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 Ranunculus actually grow on my specific land in Oregon?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores ranunculus 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 Oregon
State-level data is a sketch. Your Growable Ground report scores ranunculus against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Oregon ranunculus averages can't show:
We read public map data around Oregon — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Oregon ranunculus average
Explore More
Growing guides for ranunculus
Explore Oregon county by county
Oregon carries 36 counties with their own USDA zone — a sample of the growing pages for ranunculus there:
Where else ranunculus grows
Ranunculus's zone band crosses state lines — these are the states closest to Oregon 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 Oregon
Oregon has a growing page for 1,038 plants — a rotating sample of the rest of the shelf.
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