Harper, Oregon, sits in USDA hardiness zone 6b — a zone band wide enough that plant choice, not possibility, is the interesting question.
Reliable performers under these conditions include cabbage, blackberry, california poppy, and collard greens; what your own ground favors still comes down to its soil, sun, and drainage.
Even in Harper, 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 Harper 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 Harper — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Harper — the short answer
Harper, Oregon: USDA zone 6b, about 187 days between hard freezes, across 4K acres of town.
- USDA zone
- 6b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 16
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 20
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~187
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 4K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 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 Harper's average, not your lot's — a low corner or a tree line moves it. Against Harper's 187-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Harper
Each reading below is measured for Harper itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredHarper runs about 187 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
MeasuredHarper 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 Harper is in
Harper sits in the Snake River Plain — EPA Level III, inside the wider North American Deserts. That is read at Harper's own centroid, and it is not what its county reads: Malheur County is mostly Northern Basin and Range. The wider page above you is answering a different question about different ground.
What Grows in Harper
Every plant below cleared Harper's own zone 6b and its 187-day season. Each card opens that plant's Oregon profile. How we score.
Is it too late to plant in Harper?
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 Mar 19; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 16 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 20 — long-season crops need about 90 days of runway, quick greens only 30. Even past midsummer there is room for a true fall garden here, and garlic planted near the close carries the momentum into next year.
What's on the federal record near Harper
Closest first, within ~10 miles of Harper. Listing isn't leaking, and distance isn't exposure.
- UNION PACIFIC RR - HARPER STATIONUnderground Storage Tanks · 0.9 mi
- HUCKER GARAGEUnderground Storage Tanks · 1.0 mi
- HARPER RANCH - FEEDLOTCAFO · 1.5 mi
- COLEMAN SERVICEUnderground Storage Tanks · 4.3 mi
- LITTLE VALLEY ENTERPRISES INCBrownfields · 7.6 mi
Measured from Harper'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 Harper.
Total Sites
5
within ~10 miles of Harper
Risk Level
Low
Highest-severity
1 concentrated animal feeding operation
Sources Checked
within ~10 miles of Harper
Severity Distribution
within ~10 miles of Harper
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.
- •Large animal operations push nitrates and bacteria downstream. Below one, test your water.
Check your specific parcel in Harper
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 Harper average
Your land is one point inside Harper
Everything above resolves to Harper as a whole — one PHZM band and one 28°F frost record, read across 4K 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 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 Harper Average
Harper Average
- ●USDA Zones 6b, averaged across Harper
- ●One soil character for all of Harper
- ●Frost dates read at Harper's scale: Apr 16 to Oct 20
YOUR Parcel
- ✓Your exact zone, not Harper's 6b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Harper
Pull a site-specific report for your exact address in Harper, Oregon — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Harper averages can't show:
We read public map data around Harper — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Harper average
How we know this about Harper
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 Harper’s own record; 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 Harper
When does frost risk typically end in Harper?
The last hard freeze (28°F) in Harper typically lands around Apr 16, 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 7.
When is the first frost in Harper?
The first hard freeze (28°F) in Harper typically arrives around Oct 20, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 6, so the watching starts about Sep 20 — about 187 days after the spring freeze cleared.
How long is the growing season in Harper?
Measured between 28°F hard freezes, Harper sees about 187 frost-free days — roughly Apr 16 through Oct 20, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 7 to Oct 6, about 152 days.
Is the soil safe to grow vegetables in Harper?
The federal record around Harper is light — 5 documented sites across the 9 federal source types we checked, mostly Underground Storage Tanks entries (3), the nearest Underground Storage Tanks record about 0.9 miles out — and proximity to a documented site is information, not a diagnosis of any one yard. Growing food here starts from a strong position; a soil test before new food beds settles any site-specific question.
How do I protect my plants from frost in Harper?
From about Sep 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 Oct 20 (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 Oct 20. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Harper's scale — its 6b band and its 187-day season. Your yard writes its own version of Harper'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 Harper’s own scale
6 of the readings below were taken at Harper's own scale — its own ~187-day season between 28°F freezes, the 4,482 acres it covers and 5 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Harper's own USDA hardiness band, zones 6bUSDA PHZM 2023
- Harper's own 28°F hard-freeze dates, about Apr 16 and Oct 20 and the ~187-day span between themNOAA 1991–2020 Climate Normals
- 5 documented contamination sites on the federal record near Harper, the closest Underground Storage Tanks record about 0.9 miles out from the town centreFederal environmental registers
- Harper's boundary and the 4,482 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6b and a ~187-day seasonGrowable Ground crop-matching engine
- Harper sits in the Snake River Plain — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Harper's 4,482 acres read through its county's SSURGO summaryfrom Malheur County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Malheur 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 Malheur County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Harper's 4,482 acreswhy one lot differs from the next →
- Which side of Harper you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 4,482 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.9 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 Harper-wide figureread your own land →