Union County, in Oregon, sits in USDA hardiness zone 6b — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
On paper, cabbage, blackberry, california poppy, and collard greens all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Union County lies within the Northeast Oregon Mountain Valleys — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Union County holds more than one microclimate.
Soils and elevations shift across Union 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 Union County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Union County — the short answer
Union County, Oregon: USDA zone 6b, about 165 days between hard freezes, across 1.3M acres.
- USDA zone
- 6b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 25
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 7
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~165
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 1.3M 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 6b is Union County's average, not your lot's — a low corner or a tree line moves it. Against Union County's 165-day season, see what your own ground reads.
Heat in Union County
Across a year, Union County accumulates about 1,848 growing degree days above 50°F, about 4 fewer than the middle Oregon county — ahead of 17 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 Union County
Across Union County, the ground is predominantly Mollisols, where Limberjim, Anatone, and Syrupcreek are the most extensive named soil series. The soil is generally well drained with a ashy silt loam surface. Topsoil pH runs about 6.3–6.7, slightly acidic. Rainfall drains through hydrologic group C soils.
Soil order
Mollisols
Drainage
Well drained
Prime farmland
1%
Hydric soils
0%
Soil still varies lot by lot — soil types explained.
How the ground varies across Union County
The USDA soil survey maps 76% of Union County as well drained — but another 5% drains differently: 3% somewhat poorly drained, 2% moderately well drained.
Limberjim is the most extensive named soil at 10% of mapped acres, then Anatone (7%) and Syrupcreek (7%).
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 Union County
Each reading below is measured for Union 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 Union 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 Union County runs about pH 6.3–6.7, close to neutral.
This is the range most vegetables prefer — one correction you probably do not have to make, which is genuinely good news for a new bed.
Keep it there with compost rather than lime or sulfur, and only amend if your own soil test says otherwise.
USDA NRCS SSURGO
Season length
MeasuredUnion County runs about 165 days between hard freezes — a moderate growing season.
There is room for the full run of cool-season crops plus a warm-season main crop, but the calendar is tight enough that a late spring or early fall frost still decides how much finishes.
Time warm-season transplants to your last hard freeze, and a few weeks of season extension turns a near-miss harvest into a sure one.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredUnion County sits in USDA hardiness zone 6b.
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 Union County is in
Union County sits in the Blue Mountains — EPA Level III, inside the wider Northwestern Forested Mountains. One consistent ecological setting across the whole county.
What Grows in Union County
We scored all 1,086 plants against Union County's own USDA zone 6b and its own 165-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 Union County?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 28; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 25 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 7 — long-season crops need about 90 days of runway, quick greens only 30. Late in the year the fall bench takes over — quick greens, radishes, and garlic that repays you next summer.
Documented around Union County
- monarch butterfly11 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Union County
USGS estimates 46,350 lb of Glyphosate on Union County farmland in 2019, its largest by weight, ahead of Metribuzin (8,435 lb) and 2,4-d (4,507 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 Union County — and how to grow with it.
We checked the federal record across Union County — 210 documented sites across 6 of the 9 source types we track.
The most significant on record: 8 Toxics Release Inventory facilities. Active industrial facilities reporting chemical releases to air, water, and land.
There's a meaningful federal record across Union County — worth a look before you plant food, not a reason to hold back from growing. Proximity to a documented site is information, not a diagnosis of any one yard. A soil test before new food beds is the sensible precaution here, and the map shows exactly which sites sit where, so you can see what's actually near you.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Union County
Closest first, across Union County. Listing isn't leaking, and distance isn't exposure.
- EAGLE CAP CAMPERSBrownfields · 1.3 mi
- USFS FIRE CONTROLToxics Release Inventory · 1.4 mi
- FEDEX FREIGHT LAGBrownfields · 1.5 mi
- ORARNG LA GRANDE FMSBrownfields · 1.7 mi
- W W T PUnderground Storage Tanks · 1.7 mi
- BLUE MT FLYING J TRUCK STOPUnderground Storage Tanks · 1.9 mi
- LA GRANDE WWTPBrownfields · 1.9 mi
- HAMILTON EXCAVATIONBrownfields · 1.9 mi
- FREIGHTLINER NORTHWESTBrownfields · 2.2 mi
- CRISSTAD ENTERPRISES INCUnderground Storage Tanks · 2.2 mi
- WEISHAAR FARMSUnderground Storage Tanks · 2.3 mi
- WASTE PRO TRANSFER STATIONBrownfields · 3.0 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Union 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 Union County.
Total Sites
210
across Union County
Risk Level
Elevated
Highest-severity
8 Toxics Release Inventory facilities
Sources Checked
across Union County
Severity Distribution
across Union County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Union County, Mining runs higher than the national average — 39 sites across Union County. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Check your specific parcel in Union 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 Union County average
Your land is one point inside Union County
Everything above resolves to Union County as a whole — one PHZM band and one county frost record, read across 1.3M 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 Union County Average
Union County Average
- ●USDA Zones 6b, averaged across Union County
- ●One soil character for all of Union County
- ●Frost dates read at Union County's scale: Apr 25 to Oct 7
YOUR Parcel
- ✓Your exact zone, not Union County's 6b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Union County
Pull a site-specific report for your exact address in Union County, Oregon — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Union County averages can't show:
We read public map data around Union County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Union County average
How we know this about Union 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 Union County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Union County
When does frost risk typically end in Union County?
The last hard freeze (28°F) in Union County typically lands around Apr 25, 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 May 16.
How long is the growing season in Union County?
Measured between 28°F hard freezes, Union County sees about 165 frost-free days — roughly Apr 25 through Oct 7, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 16 to Sep 23, about 130 days.
Is the soil safe to grow vegetables in Union County?
The federal record around Union County is a meaningful one — 210 documented sites, mostly Underground Storage Tanks entries (124), the nearest Brownfields record about 1.3 miles out — so a soil test before new food beds is a sensible precaution here, not a reason to hold back from growing. Remember that proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what sits where.
Everything above is measured at Union County's scale — its 6b band and its 165-day season. Your yard writes its own version of Union 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 Union County’s own scale
9 of the readings below were taken at Union County's own scale — its own ~165-day span between 28°F freezes, the 3 most extensive soil series mapped here and 210 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Union County's own USDA hardiness band, zones 6bUSDA PHZM 2023
- Union County's own 28°F hard-freeze dates and its ~165-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Union CountyUSDA NRCS SSURGO
- 210 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Brownfields record about 1.3 miles outFederal environmental registers
- Union County's boundary and the 1,303,641 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6b and a ~165-day seasonGrowable Ground crop-matching engine
- Union County sitting wholly inside the Blue MountainsUS EPA Level III Ecoregions
- Open occurrence records documented in Union County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Union 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 Union County — the ~165 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 Union County's 1,303,641 acreswhy one lot differs from the next →
- Which of those 210 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 Union Countyread your own land →