Marion County, in Oregon, sits in USDA hardiness zone 8a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Crops well matched to these conditions include cabbage, fig, california poppy, and collard greens — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Marion County lies within the Willamette Valley and the Pacific Northwest — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Marion County holds more than one microclimate.
Soils and elevations shift across Marion County, so your frost dates and drainage aren't the county average. 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 Marion County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Marion County — the short answer
Marion County, Oregon: USDA zone 8a, about 243 days between hard freezes, across 756K acres.
- USDA zone
- 8a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 23
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Nov 21
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~243
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 756K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 8a is Marion County's average, not your lot's — a low corner or a tree line moves it. Against Marion County's 243-day season, see what your own ground reads.
One county, several growing seasons
Marion County's hard-freeze record runs about 243 days between freezes — but that is the county-wide average, and several towns inside it carry a markedly different season in their own 30-year record: Gates at about 276 days and Mehama at 276 (against the county's ~243).
Those are measured records, not estimates. If you garden in one of these pockets, plant against your own town's season rather than the county's ~243-day average.
NOAA Regional Climate Centers ACIS (1991–2020), 30-year daily minimum record. Only held-out towns carrying their own record are named — a town with no record of its own is absent rather than estimated, and a county with nothing qualifying shows no spread at all.
Heat in Marion County
Across a year, Marion County accumulates about 1,197 growing degree days above 50°F, about 655 fewer than the middle Oregon county — ahead of 2 of Oregon’s 36 counties. Degree days are the heat a crop actually gets to work with — more of them is more room to ripen a long-season crop before the freeze closes the window.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in Marion County
Across Marion County, the ground is predominantly Mollisols, where Woodburn, Nekia, and McCully are the most extensive named soil series. The soil is generally well drained with a silt loam surface. Topsoil pH runs about 5.6–6.1, moderately acidic. Rainfall drains through hydrologic group C soils.
Soil order
Mollisols
Drainage
Well drained
Prime farmland
34%
Hydric soils
11%
Soil still varies lot by lot — soil types explained.
How the ground varies across Marion County
The USDA soil survey maps 57% of Marion County as well drained — but another 42% drains differently: 19% moderately well drained, 12% somewhat poorly drained.
Woodburn is the most extensive named soil at 14% of mapped acres, then Nekia (14%) and McCully (11%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in Marion County
Each reading below is measured for Marion County itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across Marion County are well drained, in hydrologic group C — ground that drains quickly.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Marion County runs about pH 5.6–6.1, on the acidic side.
Blueberries, potatoes, and rhododendrons thrive in it, but most vegetables start locking out nutrients below about pH 6.0 and grow pale and stunted no matter how much you feed them.
A measured lime application raises pH for the crops that need it — but test first, because the right rate depends on your own soil, not the county average.
USDA NRCS SSURGO
Season length
MeasuredMarion County runs about 243 days between hard freezes — a long growing season.
There is slack for succession plantings and slow-finishing crops: many vegetables can be sown twice, and the heat-lovers have time to ripen fully.
Plan a second sowing of quick crops after the first comes out, and use the fall window most gardeners let sit idle.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredMarion County sits in USDA hardiness zone 8a.
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 Marion County is in
Marion County spans 2 EPA Level III ecoregions — Willamette Valley (53%) and Cascades (47%). Which one your land falls in changes what grows wild there and how the ground behaves, and a county-wide answer cannot tell you which.
What Grows in Marion County
We scored all 1,086 plants against Marion County's own USDA zone 8a and its own 243-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's Oregon profile.
Is it too late to plant in Marion County?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Feb 23; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 23 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 21 — long-season crops need about 90 days of runway, quick greens only 30. With a season this long, “too late” mostly means “switch crops” — second sowings and a full fall garden are the norm, with garlic closing the year.
Documented around Marion County
Survey cells within 31 miles of Marion County checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 495 miles off. What to watch for.
- monarch butterfly4 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Marion County
USGS estimates 153,592 lb of Glyphosate on Marion County farmland in 2019, its largest by weight, ahead of Ethoprophos (15,493 lb) and 2,4-d (14,690 lb).
Farmland across the whole county, not any one lot. Check your address for the site-by-site record.
Safe to Grow Here?
What the federal record shows across Marion County — and how to grow with it.
We checked the federal record across Marion County — 1,306 documented sites across 8 of the 9 source types we track.
The most significant on record: 14 Superfund sites (none NPL-listed). Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Marion County carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Marion County
Closest first, across Marion County. Listing isn't leaking, and distance isn't exposure.
- SILVER FALLS STATE PARKUnderground Storage Tanks · 5.3 mi
- SILVER MOUNTAIN CHRISTMAS TREESUnderground Storage Tanks · 6.7 mi
- NIELSON FARMSUnderground Storage Tanks · 7.1 mi
- SILVERTON, CITY OFPFAS · 7.6 mi
- OR STATE FORESTRY - SANTIAM GUARD STAUnderground Storage Tanks · 7.7 mi
- WILSON HATCHERY & POULTRY FARMUnderground Storage Tanks · 7.9 mi
- HARDWOOD COMPONENTSUnderground Storage Tanks · 8.3 mi
- HUNT, JOHNUnderground Storage Tanks · 9.2 mi
- MORGAN, VERNON R.Underground Storage Tanks · 9.5 mi
- KBSP TVUnderground Storage Tanks · 9.6 mi
- SKY CAR LOGGING, INC.Underground Storage Tanks · 9.8 mi
- STAYTON WATER SUPPLYPFAS · 10.0 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Marion County'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 Marion County.
Total Sites
1,306
across Marion County
Risk Level
High
Highest-severity
14 Superfund sites (none NPL-listed)
Severity Distribution
across Marion County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Marion County, CAFO runs higher than the national average — 15 sites across Marion County. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Check your specific parcel in Marion County
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 Marion County average
Your land is one point inside Marion County
Everything above resolves to Marion County as a whole — one PHZM band and one county frost record, read across 756K acres. 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 county 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 county average.
Your Lot vs the Marion County Average
Marion County Average
- ●USDA Zones 8a, averaged across Marion County
- ●One soil character for all of Marion County
- ●Frost dates read at Marion County's scale: Mar 23 to Nov 21
YOUR Parcel
- ✓Your exact zone, not Marion County's 8a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Marion County
Pull a site-specific report for your exact address in Marion County, Oregon — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Marion County averages can't show:
We read public map data around Marion County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Marion County average
How we know this about Marion County
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where Marion County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Marion County
When does frost risk typically end in Marion County?
The last hard freeze (28°F) in Marion County typically lands around Mar 23, 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 Apr 13.
How long is the growing season in Marion County?
Measured between 28°F hard freezes, Marion County sees about 243 frost-free days — roughly Mar 23 through Nov 21, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 13 to Nov 7, about 208 days.
Is the soil safe to grow vegetables in Marion County?
The federal record around Marion County runs heavier than most — 1,306 documented sites, mostly Underground Storage Tanks entries (774), the nearest Underground Storage Tanks record about 5.3 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.
Everything above is measured at Marion County's scale — its 8a band and its 243-day season. Your yard writes its own version of Marion County's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Oregon's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Marion County’s own scale
9 of the readings below were taken at Marion County's own scale — its own ~243-day span between 28°F freezes, the 3 most extensive soil series mapped here and 1,306 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Marion County's own USDA hardiness band, zones 8aUSDA PHZM 2023
- Marion County's own 28°F hard-freeze dates and its ~243-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Marion CountyUSDA NRCS SSURGO
- 1,306 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 5.3 miles outFederal environmental registers
- Marion County's boundary and the 755,737 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 8a and a ~243-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Marion County spans, Willamette Valley the largestUS EPA Level III Ecoregions
- Open occurrence records documented in Marion County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Marion County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Oregon grower plans around — written at state scale, so they stay on the state guidefrom Oregon
What this page can’t tell you
- How the season shifts across Marion County — the ~243 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Marion County's 755,737 acreswhy one lot differs from the next →
- Which of those 1,306 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over Marion Countyread your own land →