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

Planting zone for 97360 — Mill City, OR

ZIP code 97360 (Mill City, Linn County) is in USDA zone 8b: the coldest winter night averages 15 to 20 °F. The median last spring frost is March 9 and the first fall frost December 3.

Where ZIP 97360 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.

Zone8b15 to 20 °F
Coldest night−9.4 to −6.7 °C
Last frostMar 9
First frostDec 3
2012 zone8b

Same zone as on the 2012 map. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 8b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Mill City, 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 Mill City, OR

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 9median — 50% chance of a later frost
Safe for tender plantsApril 8only 10% chance of frost after
First fall frostDecember 3median — 10% chance by Nov 8
Growing season270 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 5 and returns around December 26.

From the NOAA station Detroit Dam, OR — 11 miles away, elevation 1,221 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 97360

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 26 – Feb 9
SpinachSow outdoors · Jan 26 – Feb 16
Broccoli, cabbageStart indoors · Dec 29 – Jan 12
Broccoli, cabbageTransplant · Feb 16 – Mar 2
Onion setsPlant outdoors · Feb 9 – Feb 23
PotatoesPlant outdoors · Feb 16 – Mar 2
LettuceSow outdoors · Feb 9 – Feb 23
Carrots, beetsSow outdoors · Feb 16 – Mar 2
TomatoesStart indoors · Jan 12 – Jan 26
TomatoesTransplant · Mar 16 – Mar 30
Peppers, eggplantStart indoors · Dec 29 – Jan 12
Peppers, eggplantTransplant · Mar 23 – Apr 6
BeansSow outdoors · Mar 16 – Mar 30
Sweet cornSow outdoors · Mar 16 – Mar 30
Cucumbers, squashSow outdoors · Mar 16 – Mar 30
Fall lettuce, spinachSow outdoors · Oct 8 – Oct 22
GarlicPlant cloves · Nov 19 – Dec 24
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 9) and first fall frost (Dec 3) 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 97360 came on Feb 13 — 11 days earlier than the 1991–2020 average (Feb 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 8b in Oregon

661 plants native to the lower 48 states, recorded in Oregon, and rated by the USDA to survive 15 °F or colder — the bottom of zone 8b. Each links to its USDA PLANTS profile.

Trees 43

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 132

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 305

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 166

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 Mill City, OR.

Soil in Mill City, OR

The soil mapped at the center of ZIP 97360 is Sifton variant — gravelly loam, somewhat excessively drained.

TextureGravelly loama good balance for most vegetables
pH5.8moderately acidic; most vegetables like 6.0–7.0
DrainageSomewhat excessively drainednatural drainage class
Organic matter3%moderate
Hydrologic groupAwater soaks in fast
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Sifton variant gravelly loam.

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 97360; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Mill City, OR

Summer high81 °Faverage high, August
Winter low36 °Faverage low, January
Hot days13days a year at 90 °F or more
Freezing nights46nights a year at 32 °F or less
Growing degree days2,304base 50 °F — the season’s usable heat
Longest day15 h 35 mindaylight on June 21
Shortest day8 h 48 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation73.9 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°32 °FJanuary: average high 43 °F, low 36 °F 43°36° JanFebruary: average high 47 °F, low 37 °F 47°37° FebMarch: average high 52 °F, low 38 °F 52°38° MarApril: average high 57 °F, low 41 °F 57°41° AprMay: average high 65 °F, low 46 °F 65°46° MayJune: average high 71 °F, low 51 °F 71°51° JunJuly: average high 80 °F, low 56 °F 80°56° JulAugust: average high 81 °F, low 56 °F 81°56° AugSeptember: average high 74 °F, low 53 °F 74°53° SepOctober: average high 61 °F, low 47 °F 61°47° OctNovember: average high 49 °F, low 40 °F 49°40° NovDecember: average high 43 °F, low 37 °F 43°37° Dec

Precipitation by month inches

0″2″4″6″8″10″12″January: 9.80 in precipitation 9.8 JanFebruary: 7.58 in precipitation 7.6 FebMarch: 7.95 in precipitation 8.0 MarApril: 7.21 in precipitation 7.2 AprMay: 5.64 in precipitation 5.6 MayJune: 3.31 in precipitation 3.3 JunJuly: 0.66 in precipitation 0.7 JulAugust: 0.82 in precipitation 0.8 AugSeptember: 2.79 in precipitation 2.8 SepOctober: 6.45 in precipitation 6.5 OctNovember: 10.31 in precipitation 10.3 NovDecember: 11.36 in precipitation 11.4 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Detroit Dam, OR (11 mi away); precipitation: Lyons 2.1 S, OR (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 8b.

973468b
Gates, OR · 5 mi
973588b
Lyons, OR · 6 mi
973848b
Mehama, OR · 7 mi
973838b
Stayton, OR · 12 mi
973858b
Sublimity, OR · 14 mi
973758b
Scotts Mills, OR · 17 mi
973818b
Silverton, OR · 18 mi
970388b
Molalla, OR · 24 mi

Oregon planting zones →

Questions about 97360

What planting zone is ZIP code 97360?

ZIP code 97360 (Mill City, OR) is in USDA hardiness zone 8b on the 2023 map: the coldest night of an average winter reaches 15 to 20 °F (−9.4 to −6.7 °C).

When is the last frost in Mill City, OR?

The median last spring frost (32 °F) near 97360 is March 9; after April 8 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Detroit Dam station.

When is the first frost in Mill City, OR?

The median first fall frost near 97360 is December 3, giving a median frost-free growing season of 270 days.

When should I plant tomatoes in 97360?

Start tomato seeds indoors around Jan 12 – Jan 26 and set transplants outside around Mar 16 – Mar 30, one to three weeks after the median last frost.

How much rain and snow does 97360 get?

About 73.9 inches of precipitation a year (NOAA 1991–2020 normals, Lyons 2.1 S station).

How hot do summers get in Mill City, OR?

The average high peaks at 81 °F in August, with about 13 days a year at 90 °F or more.

What kind of soil does 97360 have?

The USDA soil survey maps Sifton variant at the center of ZIP 97360: gravelly loam, somewhat excessively drained, pH about 5.8 (moderately acidic).

Did spring come early in Mill City, OR in 2026?

Spring leaf-out near 97360 came on Feb 13 in 2026, 11 days earlier than the 1991–2020 average (Feb 24), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Mill City, OR?

Long-day onions: the longest day near 97360 is 15 h 35 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).