Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated

Planting zone for 97721 — Princeton, OR

ZIP code 97721 (Princeton, Harney County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is May 10 and the first fall frost October 7.

Where ZIP 97721 is

Outlined: the ZIP code area · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zone6b−5 to 0 °F
Coldest night−20.6 to −17.8 °C
Last frostMay 10
First frostOct 7
2012 zone6a

Was 6a on the 2012 map — half a zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Princeton, OR…

Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Princeton, OR

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 10median — 50% chance of a later frost
Safe for tender plantsJune 3only 10% chance of frost after
First fall frostOctober 7median — 10% chance by Sep 21
Growing season145 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 27 and returns around October 19.

From the NOAA station Fields, OR — 22 miles away, elevation 4,226 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in 97721

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 29 – Apr 12
SpinachSow outdoors · Mar 29 – Apr 19
Broccoli, cabbageStart indoors · Mar 1 – Mar 15
Broccoli, cabbageTransplant · Apr 19 – May 3
Onion setsPlant outdoors · Apr 12 – Apr 26
PotatoesPlant outdoors · Apr 19 – May 3
LettuceSow outdoors · Apr 12 – Apr 26
Carrots, beetsSow outdoors · Apr 19 – May 3
TomatoesStart indoors · Mar 15 – Mar 29
TomatoesTransplant · May 17 – May 31
Peppers, eggplantStart indoors · Mar 1 – Mar 15
Peppers, eggplantTransplant · May 24 – Jun 7
BeansSow outdoors · May 17 – May 31
Sweet cornSow outdoors · May 17 – May 31
Cucumbers, squashSow outdoors · May 17 – May 31
Fall lettuce, spinachSow outdoors · Aug 12 – Aug 26
GarlicPlant cloves · Sep 23 – Oct 28
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 10) and first fall frost (Oct 7) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 97721 came on Mar 8 — 16 days earlier than the 1991–2020 average (Mar 24).

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Native plants for zone 6b in Oregon

613 plants native to the lower 48 states, recorded in Oregon, and rated by the USDA to survive −5 °F or colder — the bottom of zone 6b. Each links to its USDA PLANTS profile.

Trees 40

Alaska cedar75 ft · blooms mid spring · low shade tolerance · to −22 °Fbalsam poplar80 ft · blooms late spring · high shade tolerance · to −79 °Fbigleaf maple60 ft · blooms mid spring · medium shade tolerance · to −14 °Fblack locust60 ft · blooms spring · high shade tolerance · to −37 °Fboxelder60 ft · blooms early spring · low shade tolerance · to −46 °FBrewer spruce100 ft · blooms early summer · low shade tolerance · to −13 °F

Shrubs 114

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °Falderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °Falpine laurel1 ft · blooms late spring · low shade tolerance · to −28 °Fantelope bitterbrush6 ft · blooms early spring · medium shade tolerance · to −36 °Fbeaked hazelnut15 ft · blooms early spring · low shade tolerance · to −47 °Fbig sagebrush4 ft · blooms mid summer · high shade tolerance · to −43 °F

Wildflowers & perennials 287

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine bistort1 ft · blooms mid spring · high shade tolerance · to −38 °Falpine mountainsorrel1 ft · blooms mid summer · medium shade tolerance · to −43 °FAmerican alpine speedwell1 ft · blooms summer · medium shade tolerance · to −28 °FAmerican bistort1.5 ft · blooms mid spring · high shade tolerance · to −38 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °F

Grasses 161

Alaska brome5 ft · blooms late spring · low shade tolerance · to −18 °FAlaska oniongrass3 ft · blooms mid spring · low shade tolerance · to −33 °Falkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Falkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °Falpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °FAmerican beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °F

Vines 2

riverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fwestern white clematis1 ft · blooms mid summer · medium shade tolerance · to −38 °F

Source: USDA, NRCS. 2026. The PLANTS Database (plants.usda.gov), National Plant Data Team — state distribution, native status and the “Temperature, Minimum” characteristic. Check light, moisture and soil needs before buying; local nurseries and your state native plant society can confirm what thrives in Princeton, OR.

Soil in Princeton, OR

The soil mapped at the center of ZIP 97721 is Alvodest — silty clay loam, somewhat poorly drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH10.1alkaline; most vegetables like 6.0–7.0
DrainageSomewhat poorly drainedconsider raised beds
Organic matter0.75%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Playas.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 97721; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Princeton, OR

Summer high89 °Faverage high, July
Winter low20 °Faverage low, December
Hot days40days a year at 90 °F or more
Freezing nights144nights a year at 32 °F or less
Growing degree days2,614base 50 °F — the season’s usable heat
Longest day15 h 18 mindaylight on June 21
Shortest day9 h 03 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation42.8 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 41 °F, low 21 °F 41°21° JanFebruary: average high 46 °F, low 24 °F 46°24° FebMarch: average high 54 °F, low 30 °F 54°30° MarApril: average high 59 °F, low 34 °F 59°34° AprMay: average high 69 °F, low 42 °F 69°42° MayJune: average high 78 °F, low 48 °F 78°48° JunJuly: average high 89 °F, low 59 °F 89°59° JulAugust: average high 88 °F, low 56 °F 88°56° AugSeptember: average high 78 °F, low 47 °F 78°47° SepOctober: average high 65 °F, low 36 °F 65°36° OctNovember: average high 50 °F, low 27 °F 50°27° NovDecember: average high 40 °F, low 20 °F 40°20° Dec

Precipitation by month inches

0″2″4″6″January: 5.72 in precipitation 5.7 JanFebruary: 4.78 in precipitation 4.8 FebMarch: 5.43 in precipitation 5.4 MarApril: 4.93 in precipitation 4.9 AprMay: 4.16 in precipitation 4.2 MayJune: 2.24 in precipitation 2.2 JunJuly: 0.46 in precipitation 0.5 JulAugust: 0.63 in precipitation 0.6 AugSeptember: 1.01 in precipitation 1.0 SepOctober: 2.56 in precipitation 2.6 OctNovember: 4.30 in precipitation 4.3 NovDecember: 6.57 in precipitation 6.6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Fields, OR (22 mi away); precipitation: Fish Creek, OR (16 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

3 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

977366b
Frenchglen, OR · 25 mi
977106b
Fields, OR · 27 mi
977226a
Diamond, OR · 36 mi
894217a
Mc Dermitt, NV · 42 mi
894046b
Denio, NV · 52 mi
979106b
Jordan Valley, OR · 53 mi
977326a
Crane, OR · 67 mi
979066b
Harper, OR · 72 mi

Oregon planting zones →

Questions about 97721

What planting zone is ZIP code 97721?

ZIP code 97721 (Princeton, OR) is in USDA hardiness zone 6b on the 2023 map: the coldest night of an average winter reaches −5 to 0 °F (−20.6 to −17.8 °C).

When is the last frost in Princeton, OR?

The median last spring frost (32 °F) near 97721 is May 10; after June 3 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Fields station.

When is the first frost in Princeton, OR?

The median first fall frost near 97721 is October 7, giving a median frost-free growing season of 145 days.

When should I plant tomatoes in 97721?

Start tomato seeds indoors around Mar 15 – Mar 29 and set transplants outside around May 17 – May 31, one to three weeks after the median last frost.

How much rain and snow does 97721 get?

About 42.8 inches of precipitation a year (NOAA 1991–2020 normals, Fish Creek station).

How hot do summers get in Princeton, OR?

The average high peaks at 89 °F in July, with about 40 days a year at 90 °F or more.

What kind of soil does 97721 have?

The USDA soil survey maps Alvodest at the center of ZIP 97721: silty clay loam, somewhat poorly drained, pH about 10.1 (alkaline).

Did spring come early in Princeton, OR in 2026?

Spring leaf-out near 97721 came on Mar 8 in 2026, 16 days earlier than the 1991–2020 average (Mar 24), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Princeton, OR?

Long-day onions: the longest day near 97721 is 15 h 18 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 97721 change?

Yes. The 2012 USDA map put 97721 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.