Monroe, Oregon, sits in USDA hardiness zone 8b — a zone band wide enough that plant choice, not possibility, is the interesting question.
A short list that earns its place here — cabbage, fig, california poppy, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Even in Monroe, 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 Monroe 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 Monroe — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Monroe — the short answer
Monroe, Oregon: USDA zone 8b, about 256 days between hard freezes, across 330 acres of city.
- USDA zone
- 8b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 8
- Benton County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Nov 19
- Benton County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~256
- Benton County normal — NOAA 1991–2020, nearest to this town
- City area
- 330 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 Benton County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 8b is Monroe's average, not your lot's — a low corner or a tree line moves it. Against Monroe's 256-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Monroe
Each reading below is measured for Monroe itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsMonroe runs about 256 days between hard freezes (read from Benton County, the closest normal to Monroe) — 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
MeasuredMonroe sits in USDA hardiness zone 8b.
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 Monroe is in
Monroe sits in the Willamette Valley — EPA Level III, inside the wider Marine West Coast Forest. That is read at Monroe's own centroid rather than borrowed from Benton County.
What Grows in Monroe
Every plant below cleared Monroe's own zone 8b and its 256-day season. Each card opens that plant's Oregon profile. How we score.
Is it too late to plant in Monroe?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Feb 8; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 8 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 19 — 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 Monroe
Survey cells within 31 miles of Monroe checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 457 miles off. What to watch for.
What's on the federal record near Monroe
Closest first, within ~10 miles of Monroe. Listing isn't leaking, and distance isn't exposure.
- BOB LEISUREUnderground Storage Tanks · 350 ft
- WECO MONROE CFNUnderground Storage Tanks · 500 ft
- BUTLERS' HARDWAREUnderground Storage Tanks · 500 ft
- MONROE FUEL, INC.Underground Storage Tanks · 600 ft
- USWEST - MONROE RADIO - 010314Underground Storage Tanks · 600 ft
- MONROE ATCBIUnderground Storage Tanks · 600 ft
- MONROE BRICK AND TILE COUnderground Storage Tanks · 2200 ft
- HARELINE DUBBIN LLC.Brownfields · 0.6 mi
- NW NATURAL GASUnderground Storage Tanks · 1.2 mi
- STRODA, ROBERT JUnderground Storage Tanks · 2.4 mi
- ALPINE GARAGEUnderground Storage Tanks · 3.1 mi
- CROCKER FARMSUnderground Storage Tanks · 3.3 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Monroe'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 Monroe.
Total Sites
121
within ~10 miles of Monroe
Risk Level
Moderate
Highest-severity
11 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Monroe
Severity Distribution
within ~10 miles of Monroe
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Monroe, two things run higher than the national average within ~10 miles of Monroe — Toxics Release Inventory (11 sites) and Underground Storage Tanks (77 sites). That's not a problem with your land — it's information about it.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Monroe
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 Monroe average
Your land is one point inside Monroe
Everything above resolves to Monroe as a whole — one PHZM band, read across 330 acres, with hard-freeze dates borrowed from Benton County’s record because no 30-year normal resolves at this city’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 city 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 Monroe Average
Monroe Average
- ●USDA Zones 8b, averaged across Monroe
- ●One soil character for all of Monroe
- ●Frost dates read at Monroe's scale: Mar 8 to Nov 19
YOUR Parcel
- ✓Your exact zone, not Monroe's 8b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Monroe
Pull a site-specific report for your exact address in Monroe, Oregon — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Monroe averages can't show:
We read public map data around Monroe — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Monroe average
How we know this about Monroe
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Benton 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 city grain anywhere on this page — there is no city-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 Monroe
When does frost risk typically end in Monroe?
The last hard freeze (28°F) in Monroe typically lands around Mar 8, 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 29.
When is the first frost in Monroe?
The first hard freeze (28°F) in Monroe typically arrives around Nov 19, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 5, so the watching starts about Oct 20 — about 256 days after the spring freeze cleared.
How long is the growing season in Monroe?
Measured between 28°F hard freezes, Monroe sees about 256 frost-free days — roughly Mar 8 through Nov 19, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Mar 29 to Nov 5, about 221 days.
Is the soil safe to grow vegetables in Monroe?
The federal record around Monroe shows 121 documented sites, mostly Underground Storage Tanks entries (77), the nearest Underground Storage Tanks record under a tenth of a mile out — a typical footprint for a growing area, and proximity to a documented site is information, not a diagnosis of any one yard. It's worth seeing which recorded sites sit closest to where you grow, and testing the soil before new food beds near any of them.
How do I protect my plants from frost in Monroe?
From about Oct 20 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 Nov 19 (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 Nov 19. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Monroe's scale — its 8b band and its 256-day season. Your yard writes its own version of Monroe'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 Monroe’s own scale
6 of the readings below were taken at Monroe's own scale — the 330 acres it covers and 121 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Monroe's own USDA hardiness band, zones 8bUSDA PHZM 2023
- 121 documented contamination sites on the federal record near Monroe, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Monroe's boundary and the 330 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 8b and a ~256-day seasonGrowable Ground crop-matching engine
- The ecoregion at Monroe's own centroid, the Willamette ValleyUS EPA Level III Ecoregions
- Lanternfly survey cells around Monroe checked, none carrying a detectionlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- The 28°F hard-freeze dates — Monroe has no normal of its own, so its county's is the closest measured readfrom Benton County
- Soil character — no town-scale survey exists, so Monroe's 330 acres read through its county's SSURGO summaryfrom Benton County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Benton 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 Benton County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Monroe's 330 acreswhy one lot differs from the next →
- Which side of Monroe you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 330 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record under a tenth of a mile 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 Monroe-wide figureread your own land →