Three Rivers, Oregon, sits in USDA hardiness zone 6a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
The conditions favor cabbage, blackberry, california poppy, and collard greens, among others — though every individual site edits that list with its own soil, sun, and drainage.
Even in Three Rivers, 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 Three Rivers 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 Three Rivers — soil, climate, flood, and parcel records. How we handle your address.
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Three Rivers — the short answer
Three Rivers, Oregon: USDA zone 6a, about 129 days between hard freezes, across 5K acres of town.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 23
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Sep 29
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~129
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 5K 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 6a is Three Rivers's average, not your lot's — a low corner or a tree line moves it. Against Three Rivers's 129-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Three Rivers
Each reading below is measured for Three Rivers itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredThree Rivers runs about 129 days between hard freezes — a short growing season.
Long-maturing crops like melons, sweet potatoes, and winter squash can run out of runway before the first hard freeze, ripening late or not at all.
Lead with fast-maturing varieties, and stretch the season on both ends with cold frames, low tunnels, or a greenhouse.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredThree Rivers sits in USDA hardiness zone 6a.
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 Three Rivers is in
Three Rivers sits in the Eastern Cascades Slopes and Foothills — EPA Level III, inside the wider Northwestern Forested Mountains. That is read at Three Rivers's own centroid rather than borrowed from Deschutes County.
What Grows in Three Rivers
Every plant below cleared Three Rivers's own zone 6a and its 129-day season. Each card opens that plant's Oregon profile. How we score.
Is it too late to plant in Three Rivers?
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 Apr 25; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 23 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Sep 29 — long-season crops need about 90 days of runway, quick greens only 30. When the window is tight, the fall moves are quick ones — baby greens, radishes, and garlic set for next season.
What's on the federal record near Three Rivers
Closest first, within ~10 miles of Three Rivers. Listing isn't leaking, and distance isn't exposure.
- 20.00S/11.00E-18CDC1Nitrate · 1900 ft
- 20S/11E-18BCDNitrate · 2100 ft
- 17348 Harlequin (GFE)Nitrate · 2500 ft
- DEQ2006, 17348 Harlequin (MW Drain)Nitrate · 2500 ft
- 20.00S/11.00E-18CAANitrate · 0.5 mi
- 20.00S/11.00E-19BDBNitrate · 0.6 mi
- 20.00S/11.00E-18ACC1Nitrate · 0.6 mi
- 20.00S/11.00E-18ACA2Nitrate · 0.8 mi
- 20.00S/11.00E-18ACA1Nitrate · 0.8 mi
- DEQ213, 16981 Sharp DriveNitrate · 0.8 mi
- 20.00S/10.00E-13CDBNitrate · 0.8 mi
- 55726 Swan Road, Sunriver (TFEP)Nitrate · 0.9 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Three Rivers'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 Three Rivers.
Sources Checked
within ~10 miles of Three Rivers
Severity Distribution
within ~10 miles of Three Rivers
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Three Rivers, Nitrate runs higher than the national average — 192 sites within ~10 miles of Three Rivers. That's not a problem with your land — it's information about it.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Three Rivers
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 Three Rivers average
Your land is one point inside Three Rivers
Everything above resolves to Three Rivers as a whole — one PHZM band and one 28°F frost record, read across 5K 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 Three Rivers Average
Three Rivers Average
- ●USDA Zones 6a, averaged across Three Rivers
- ●One soil character for all of Three Rivers
- ●Frost dates read at Three Rivers's scale: May 23 to Sep 29
YOUR Parcel
- ✓Your exact zone, not Three Rivers's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Three Rivers
Pull a site-specific report for your exact address in Three Rivers, Oregon — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Three Rivers averages can't show:
We read public map data around Three Rivers — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Three Rivers average
How we know this about Three Rivers
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 Three Rivers’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 Three Rivers
When does frost risk typically end in Three Rivers?
The last hard freeze (28°F) in Three Rivers typically lands around May 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 Jun 13.
When is the first frost in Three Rivers?
The first hard freeze (28°F) in Three Rivers typically arrives around Sep 29, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 15, so the watching starts about Aug 30 — about 129 days after the spring freeze cleared.
How long is the growing season in Three Rivers?
Measured between 28°F hard freezes, Three Rivers sees about 129 frost-free days — roughly May 23 through Sep 29, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 13 to Sep 15, about 94 days.
Is the soil safe to grow vegetables in Three Rivers?
The federal record around Three Rivers is a meaningful one — 214 documented sites, mostly Nitrate entries (192), the nearest Nitrate record about 0.4 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 gardeners stretch the season in Three Rivers?
With about 129 frost-free days between hard freezes, Three Rivers rewards the classic extension moves: floating row cover buys roughly two to four extra weeks at each shoulder — on this season that is a working window nearer 157 to 185 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 23 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Three Rivers's scale — its 6a band and its 129-day season. Your yard writes its own version of Three Rivers'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 Three Rivers’s own scale
6 of the readings below were taken at Three Rivers's own scale — its own ~129-day season between 28°F freezes, the 4,819 acres it covers and 214 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Three Rivers's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Three Rivers's own 28°F hard-freeze dates, about May 23 and Sep 29 and the ~129-day span between themNOAA 1991–2020 Climate Normals
- 214 documented contamination sites on the federal record near Three Rivers, the closest Nitrate record about 0.4 miles out from the town centreFederal environmental registers
- Three Rivers's boundary and the 4,819 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~129-day seasonGrowable Ground crop-matching engine
- The ecoregion at Three Rivers's own centroid, the Eastern Cascades Slopes and FoothillsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Three Rivers's 4,819 acres read through its county's SSURGO summaryfrom Deschutes County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Deschutes 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 Deschutes County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Three Rivers's 4,819 acreswhy one lot differs from the next →
- Which side of Three Rivers you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 4,819 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate record about 0.4 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 Three Rivers-wide figureread your own land →