Dunthorpe, Oregon, sits in USDA hardiness zone 9a — a zone band wide enough that plant choice, not possibility, is the interesting question.
Among the crops suited to this profile: artichoke, fig, california poppy, and cabbage. The site-level story — soil, sun, drainage — decides the rest.
Even in Dunthorpe, 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 Dunthorpe 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 Dunthorpe — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Dunthorpe — the short answer
Dunthorpe, Oregon: USDA zone 9a, about 292 days between hard freezes, across 673 acres of town.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Feb 13
- Multnomah County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 2
- Multnomah County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~292
- Multnomah County normal — NOAA 1991–2020, nearest to this town
- Town area
- 673 acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. No 30-year normal resolves at this town’s own centroid, so the hard-freeze dates are Multnomah County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9a is Dunthorpe's average, not your lot's — a low corner or a tree line moves it. Against Dunthorpe's 292-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Dunthorpe
Each reading below is measured for Dunthorpe itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsDunthorpe runs about 292 days between hard freezes (read from Multnomah County, the closest normal to Dunthorpe) — close to year-round growing.
Frost is rarely the limit here; winter plantings are as real as summer ones, and the harder question is which crops shrug off the summer heat.
Grow cool-season crops through the mild winter, and choose heat-tolerant varieties for the summer beds.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredDunthorpe sits in USDA hardiness zone 9a.
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 Dunthorpe is in
Dunthorpe sits in the Willamette Valley — EPA Level III, inside the wider Marine West Coast Forest. That is read at Dunthorpe's own centroid rather than borrowed from Multnomah County.
What Grows in Dunthorpe
Every plant below cleared Dunthorpe's own zone 9a and its 292-day season. Each card opens that plant's Oregon profile. How we score.
Is it too late to plant in Dunthorpe?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Jan 16; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 13 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 2 — long-season crops need about 90 days of runway, quick greens only 30. Here the calendar nearly circles: cool-season crops take the winter shift, and the next window is always close.
Documented around Dunthorpe
Survey cells within 31 miles of Dunthorpe checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 532 miles off. What to watch for.
What's on the federal record near Dunthorpe
Closest first, within ~10 miles of Dunthorpe. Listing isn't leaking, and distance isn't exposure.
- BERRY BOTANIC GARDEN THEBrownfields · 700 ft
- OREGON PARKS & RECREATION DEPT TRYON CRKBrownfields · 0.7 mi
- TRYON STATE PARKUnderground Storage Tanks · 0.7 mi
- ASTRO #215Underground Storage Tanks · 0.8 mi
- MILWAUKIE 76Underground Storage Tanks · 0.8 mi
- COBB PROPERTYUnderground Storage Tanks · 0.8 mi
- FORMER EASTMAN GARAGEUnderground Storage Tanks · 0.8 mi
- CHEVRON USA INC - 93541Underground Storage Tanks · 0.8 mi
- KELLOGG CREEK SEWAGE TREATMENT PLANTUnderground Storage Tanks · 0.8 mi
- DBA OLSON BROS MILWAUKIE TEXACOUnderground Storage Tanks · 0.8 mi
- FORMERLY BATTERY EXCHANGEUnderground Storage Tanks · 0.9 mi
- WAVERLY COUNTRY CLUBUnderground Storage Tanks · 0.9 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Dunthorpe'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 Dunthorpe.
Sources Checked
within ~10 miles of Dunthorpe
Severity Distribution
within ~10 miles of Dunthorpe
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
- •TRI facilities report what they release. Check the wind — downwind beds catch more of it.
Check your specific parcel in Dunthorpe
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 Dunthorpe average
Your land is one point inside Dunthorpe
Everything above resolves to Dunthorpe as a whole — one PHZM band, read across 673 acres, with hard-freeze dates borrowed from Multnomah County’s record because no 30-year normal resolves at this town’s own centroid. 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 Dunthorpe Average
Dunthorpe Average
- ●USDA Zones 9a, averaged across Dunthorpe
- ●One soil character for all of Dunthorpe
- ●Frost dates read at Dunthorpe's scale: Feb 13 to Dec 2
YOUR Parcel
- ✓Your exact zone, not Dunthorpe's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Dunthorpe
Pull a site-specific report for your exact address in Dunthorpe, Oregon — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Dunthorpe averages can't show:
We read public map data around Dunthorpe — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Dunthorpe average
How we know this about Dunthorpe
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 Multnomah County’s record, because none resolves here; 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 Dunthorpe
When does frost risk typically end in Dunthorpe?
The last hard freeze (28°F) in Dunthorpe typically lands around Feb 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 Mar 6.
When is the first frost in Dunthorpe?
The first hard freeze (28°F) in Dunthorpe typically arrives around Dec 2, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 18, so the watching starts about Nov 2 — about 292 days after the spring freeze cleared.
How long is the growing season in Dunthorpe?
Measured between 28°F hard freezes, Dunthorpe sees about 292 frost-free days — roughly Feb 13 through Dec 2, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Mar 6 to Nov 18, about 257 days.
Is the soil safe to grow vegetables in Dunthorpe?
The federal record around Dunthorpe runs heavier than most — 4,151 documented sites, mostly Underground Storage Tanks entries (2,277), the nearest Brownfields record about 0.1 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 I protect my plants from frost in Dunthorpe?
From about Nov 2 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Dec 2 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Dec 2. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Dunthorpe's scale — its 9a band and its 292-day season. Your yard writes its own version of Dunthorpe'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 Dunthorpe’s own scale
6 of the readings below were taken at Dunthorpe's own scale — the 673 acres it covers and 4,151 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Dunthorpe's own USDA hardiness band, zones 9aUSDA PHZM 2023
- 4,151 documented contamination sites on the federal record near Dunthorpe, the closest Brownfields record about 0.1 miles out from the town centreFederal environmental registers
- Dunthorpe's boundary and the 673 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~292-day seasonGrowable Ground crop-matching engine
- The ecoregion at Dunthorpe's own centroid, the Willamette ValleyUS EPA Level III Ecoregions
- Lanternfly survey cells around Dunthorpe checked, none carrying a detectionlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- The 28°F hard-freeze dates — Dunthorpe has no normal of its own, so its county's is the closest measured readfrom Multnomah County
- Soil character — no town-scale survey exists, so Dunthorpe's 673 acres read through its county's SSURGO summaryfrom Multnomah County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Multnomah County
- The growing challenges every Oregon grower plans around — written at state scale, so they stay on the state guidefrom Oregon
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Multnomah County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Dunthorpe's 673 acreswhy one lot differs from the next →
- Which side of Dunthorpe you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 673 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.1 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 Dunthorpe-wide figureread your own land →