Hillsboro, Oregon, sits in USDA hardiness zone 8b — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Expect cabbage, fig, california poppy, and collard greens to be strong candidates here; the deciding factors on any one parcel stay local — soil, sun, and drainage.
Even in Hillsboro, 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 Hillsboro 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 Hillsboro — soil, climate, flood, and parcel records. How we handle your address.
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Hillsboro — the short answer
Hillsboro, Oregon: USDA zone 8b, about 274 days between hard freezes, across 17K acres of city.
- USDA zone
- 8b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Feb 22
- Washington County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Nov 23
- Washington County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~274
- Washington County normal — NOAA 1991–2020, nearest to this town
- City area
- 17K 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 Washington County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 8b is Hillsboro's average, not your lot's — a low corner or a tree line moves it. Against Hillsboro's 274-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Hillsboro
Each reading below is measured for Hillsboro itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsHillsboro runs about 274 days between hard freezes (read from Washington County, the closest normal to Hillsboro) — 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
MeasuredHillsboro 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 Hillsboro is in
Hillsboro sits in the Willamette Valley — EPA Level III, inside the wider Marine West Coast Forest. That is read at Hillsboro's own centroid rather than borrowed from Washington County.
What Grows in Hillsboro
Every plant below cleared Hillsboro's own zone 8b and its 274-day season. Each card opens that plant's Oregon profile. How we score.
Is it too late to plant in Hillsboro?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Jan 25; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 22 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 23 — long-season crops need about 90 days of runway, quick greens only 30. With almost year-round growing weather, timing is about heat and rainfall more than frost — some bench is always in play.
Documented around Hillsboro
Survey cells within 31 miles of Hillsboro checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 539 miles off. What to watch for.
What's on the federal record near Hillsboro
Closest first, within ~10 miles of Hillsboro. Listing isn't leaking, and distance isn't exposure.
- GLIDEWELL DENTALBrownfields · 1300 ft
- INTEL CORP HAWTHORN FARMToxics Release Inventory · 1600 ft
- INTEL CORP HAWTHORN FARMBrownfields · 1600 ft
- COORSTEKBrownfields · 1600 ft
- COORSTEKToxics Release Inventory · 1600 ft
- PENTAGON EMS CORPORATIONToxics Release Inventory · 1900 ft
- LATTICE SEMICONDUCTORBrownfields · 0.5 mi
- HILLSBORO AVIATIONBrownfields · 0.5 mi
- POWER PROTECTION PLUSBrownfields · 0.6 mi
- CASCADE SYSTEMS TECHNOLOGYBrownfields · 0.6 mi
- 01S/02W-04ABANitrate · 0.6 mi
- KAISER HILLSBORO MEDICAL OFFICEBrownfields · 0.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Hillsboro'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 Hillsboro.
Sources Checked
within ~10 miles of Hillsboro
Severity Distribution
within ~10 miles of Hillsboro
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Hillsboro, Toxics Release Inventory runs higher than the national average — 91 sites within ~10 miles of Hillsboro. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Check your specific parcel in Hillsboro
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 Hillsboro average
Your land is one point inside Hillsboro
Everything above resolves to Hillsboro as a whole — one PHZM band, read across 17K acres, with hard-freeze dates borrowed from Washington 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 Hillsboro Average
Hillsboro Average
- ●USDA Zones 8b, averaged across Hillsboro
- ●One soil character for all of Hillsboro
- ●Frost dates read at Hillsboro's scale: Feb 22 to Nov 23
YOUR Parcel
- ✓Your exact zone, not Hillsboro's 8b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Hillsboro
Pull a site-specific report for your exact address in Hillsboro, Oregon — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Hillsboro averages can't show:
We read public map data around Hillsboro — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Hillsboro average
How we know this about Hillsboro
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 Washington 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 Hillsboro
When does frost risk typically end in Hillsboro?
The last hard freeze (28°F) in Hillsboro typically lands around Feb 22, 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 15.
When is the first frost in Hillsboro?
The first hard freeze (28°F) in Hillsboro typically arrives around Nov 23, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 9, so the watching starts about Oct 24 — about 274 days after the spring freeze cleared.
How long is the growing season in Hillsboro?
Measured between 28°F hard freezes, Hillsboro sees about 274 frost-free days — roughly Feb 22 through Nov 23, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Mar 15 to Nov 9, about 239 days.
Is the soil safe to grow vegetables in Hillsboro?
The federal record around Hillsboro is a meaningful one — 1,372 documented sites, mostly Underground Storage Tanks entries (641), the nearest Brownfields record about 0.2 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.
How do I protect my plants from frost in Hillsboro?
From about Oct 24 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 23 (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 23. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Hillsboro's scale — its 8b band and its 274-day season. Your yard writes its own version of Hillsboro'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 Hillsboro’s own scale
6 of the readings below were taken at Hillsboro's own scale — the 16,924 acres it covers and 1,372 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Hillsboro's own USDA hardiness band, zones 8bUSDA PHZM 2023
- 1,372 documented contamination sites on the federal record near Hillsboro, the closest Brownfields record about 0.2 miles out from the town centreFederal environmental registers
- Hillsboro's boundary and the 16,924 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 8b and a ~274-day seasonGrowable Ground crop-matching engine
- The ecoregion at Hillsboro's own centroid, the Willamette ValleyUS EPA Level III Ecoregions
- Lanternfly survey cells around Hillsboro checked, none carrying a detectionlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- The 28°F hard-freeze dates — Hillsboro has no normal of its own, so its county's is the closest measured readfrom Washington County
- Soil character — no town-scale survey exists, so Hillsboro's 16,924 acres read through its county's SSURGO summaryfrom Washington County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Washington 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 Washington County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Hillsboro's 16,924 acreswhy one lot differs from the next →
- Which side of Hillsboro you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 16,924 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.2 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 Hillsboro-wide figureread your own land →