Unlikely — Zone Mismatch
Japanese mint (zones 11-13) does not overlap with Oregon's zone range (5a-10a). Growing outdoors is unlikely without significant protection.
2 zones short — what would close it
Japanese Mint is hardy to zone 11, and the warmest ground in Oregon is zone 9 — 2 zones short. Planted in open ground it will not survive a Oregon winter. To grow it here, grow japanese mint under glass — a greenhouse is the only lift this wide the engine models.
A greenhouse is the lift this needs. How a greenhouse changes what you can grow →
Zone math from 11-13 (plant) against 5-9 (Oregon). Lift modeled by crop_engine Sprint 20B effective_zone_modifier (+2 zones) via api/fast_sections.py Unlock Engine v2.
Your yard isn't the whole zone.
Oregon spans zones 5a-10a, 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 japanese mint 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.
No card required · your full report in seconds
Zone Comparison
Japanese Mint Needs
- USDA Zones: 11-13
- Frost-Free Days: 120+
- Sun: Full Sun
- 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 11-13)
Preferred Soil pH
Plant data: USDA PLANTS Database / Growable Ground plant catalog. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Japanese Mint 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.
Winter standing
Oregon runs as cold as USDA zone 5, and no sourced winter-hardiness floor is on record for japanese mint, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether japanese mint is a permanent planting or a replant-every-spring crop for you turns on your own zone within Oregon; check its hardiness range against that before treating it as long-lived ground.
Timing tuned to sub-state frost dates — Klamath County, not the statewide average.
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 japanese mint does not survive a Oregon winter in the ground. The season figures below measure a different question — whether it could finish a season here at all — and they only bear on Oregon under protection.
Frost-free days
Japanese Mint wants 120+ frost-free days; a typical Oregon site sees ~213 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
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
Japanese Mint tolerates a wide pH range (pH 4.5-8.3) — 3.8 units, acid ground through alkaline — so soil acidity is rarely what limits it in Oregon. A soil test is still worth having, but for what else it tells you about this site, not to clear this plant. It will grow across that whole span, but it does best between pH 5.5 and 6.4 — worth knowing before you decide whether a Oregon soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Oregon site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
Oregon's soils run mostly silt loam, but SSURGO maps the series, texture, and drainage under your exact parcel. Japanese Mint needs about 19 inches of workable depth, so it is that horizon — not the surface — you are testing for. That map unit, not the state average, decides how japanese mint performs.
Check your parcel → Source: USDA NRCS SSURGO.
Plant pH and drainage requirements from USDA PLANTS Database. Oregon soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Japanese Mint in Oregon — Quick Answer
- Verdict: Unlikely — Zone Mismatch
- Plant Zones: 11-13 (USDA PLANTS Database)
- State Zones: 5a-10a (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about Feb 25 - Apr 26 to Oct 19 - Nov 26 (NOAA Regional Climate Centers ACIS, 1991-2020)
What Else to Consider for Japanese Mint 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)
Growing japanese mint here specifically
Japanese Mint needs pH 4.5–8.3; Oregon's dominant silt loam soils may or may not deliver that, so your parcel's SSURGO map unit is the real test.
Start with a soil test on your own ground and adjust pH and texture to fit japanese mint's 4.5–8.3 range. How to handle it →
What to actually do about these — and the constraints that apply to every Oregon grower, not just japanese mint — is covered on the Oregon growing guide.
Timing shifts within Oregon
Oregon isn't one climate. In Klamath County, the last hard freeze (28°F) holds until about Jun 9 — roughly 67 days later than the recorded state median — so plant japanese mint to your county's window, not the statewide date.
Japanese Mint needs about 120 days of frost-free season to complete its cycle. 35 of Oregon’s 36 counties give it that outright. The tightest that does is Lake County at 134 frost-free days — 14 to spare. Below that line you are transplanting or extending the season, not direct-sowing.
Across Oregon’s 36 counties the frost-free season runs from 86 days in Klamath County to 308 days in Lincoln County — a spread of 222 days, which is why a single statewide planting date misleads. The median Oregon county sees 213 frost-free days, leaving japanese mint about 93 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"). Japanese Mint's 120-day requirement: USDA PLANTS / Growable Ground plant database (minimum frost-free days). A parcel report resolves your address's own frost dates.
Pollinator + Wildlife Value
Japanese Mint draws honeybees and native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, japanese mint 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 japanese mint, 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 Japanese Mint in Oregon
When can I plant Japanese Mint 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). No sourced winter-hardiness floor is on record for Japanese Mint, so this page does not state whether it overwinters in Oregon 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 Japanese Mint grown in across Oregon?
Oregon spans USDA hardiness zones 5a-10a (USDA ARS PHZM 2023). Japanese Mint carries a range of zones 11-13, 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). Japanese Mint needs 120+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date. In cooler counties like Klamath, the freeze-free season runs shorter than the state average, so verify your own county's window.
How should I amend the soil for Japanese Mint in Oregon?
Japanese Mint tolerates pH 4.5-8.3 and well (dry spells) drainage (FAO ECOCROP). That is a 3.8-unit span, acid ground through alkaline, so pH is rarely what limits this plant on a Oregon site — amend for drainage and organic matter first.
Will Japanese Mint actually grow on my specific land in Oregon?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores japanese mint 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 japanese mint against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Oregon japanese mint 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 japanese mint average
Explore More
Growing guides for japanese mint
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
Last updated: