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

Planting zone for Kennewick, WA

Kennewick, WA is in USDA zone 7b across its 3 ZIP codes. The median last spring frost is March 28 and the first fall frost October 30.

Kennewick on the zone map

Outlined: its 3 ZIP code areas · 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.

Zone7b5 to 10 °F
ZIP codes3
Last frostMar 28
First frostOct 30
Growing season216 days

7b 3 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Kennewick, WA…

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 Kennewick, WA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 28median — 50% chance of a later frost
Safe for tender plantsApril 10only 10% chance of frost after
First fall frostOctober 30median — 10% chance by Oct 18
Growing season216 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 8 and returns around November 11.

From the NOAA station Kennewick, WA, elevation 390 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 Kennewick

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 14 – Feb 28
SpinachSow outdoors · Feb 14 – Mar 7
Broccoli, cabbageStart indoors · Jan 17 – Jan 31
Broccoli, cabbageTransplant · Mar 7 – Mar 21
Onion setsPlant outdoors · Feb 28 – Mar 14
PotatoesPlant outdoors · Mar 7 – Mar 21
LettuceSow outdoors · Feb 28 – Mar 14
Carrots, beetsSow outdoors · Mar 7 – Mar 21
TomatoesStart indoors · Jan 31 – Feb 14
TomatoesTransplant · Apr 4 – Apr 18
Peppers, eggplantStart indoors · Jan 17 – Jan 31
Peppers, eggplantTransplant · Apr 11 – Apr 25
BeansSow outdoors · Apr 4 – Apr 18
Sweet cornSow outdoors · Apr 4 – Apr 18
Cucumbers, squashSow outdoors · Apr 4 – Apr 18
Fall lettuce, spinachSow outdoors · Sep 4 – Sep 18
GarlicPlant cloves · Oct 16 – Nov 20
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 28) and first fall frost (Oct 30) 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 99336 came on Mar 1 — 8 days earlier than the 1991–2020 average (Mar 9).

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 7b in Washington

592 plants native to the lower 48 states, recorded in Washington, and rated by the USDA to survive 5 °F or colder — the bottom of zone 7b. Each links to its USDA PLANTS profile.

Trees 31

Alaska cedar75 ft · blooms mid spring · low shade tolerance · to −22 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °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 °F

Shrubs 105

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falpine laurel1 ft · blooms late spring · low shade tolerance · to −28 °FAmerican plum24 ft · blooms mid spring · high shade tolerance · to −38 °Fantelope bitterbrush6 ft · blooms early spring · medium shade tolerance · to −36 °FBarclay's willow15 ft · high shade tolerance · to −43 °F

Wildflowers & perennials 284

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 157

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 3

riverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Ftrumpet creeper2 ft · blooms summer · high shade tolerance · to −13 °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 Kennewick, WA.

Soil in Kennewick, WA

The soil mapped at the center of ZIP 99336 is Finley — fine sandy loam, well drained.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding
pH7.6slightly alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter0.85%low — add compost
Hydrologic groupAwater soaks in fast
Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Finley fine sandy loam, 0 to 2 percent slopes.

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 99336; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Kennewick, WA

Summer high91 °Faverage high, July
Winter low29 °Faverage low, January
Hot days48days a year at 90 °F or more
Freezing nights76nights a year at 32 °F or less
Growing degree days3,502base 50 °F — the season’s usable heat
Longest day15 h 46 mindaylight on June 21
Shortest day8 h 37 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation8.9 inper year, rain and melted snow

Average high and low, by month

20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 42 °F, low 29 °F 42°29° JanFebruary: average high 48 °F, low 31 °F 48°31° FebMarch: average high 58 °F, low 36 °F 58°36° MarApril: average high 66 °F, low 42 °F 66°42° AprMay: average high 75 °F, low 50 °F 75°50° MayJune: average high 82 °F, low 56 °F 82°56° JunJuly: average high 91 °F, low 62 °F 91°62° JulAugust: average high 90 °F, low 61 °F 90°61° AugSeptember: average high 81 °F, low 53 °F 81°53° SepOctober: average high 66 °F, low 43 °F 66°43° OctNovember: average high 51 °F, low 35 °F 51°35° NovDecember: average high 42 °F, low 30 °F 42°30° Dec

Precipitation by month inches

0″1″2″January: 1.19 in precipitation 1.2 JanFebruary: 0.91 in precipitation 0.9 FebMarch: 0.70 in precipitation 0.7 MarApril: 0.75 in precipitation 0.8 AprMay: 0.91 in precipitation 0.9 MayJune: 0.74 in precipitation 0.7 JunJuly: 0.25 in precipitation 0.3 JulAugust: 0.20 in precipitation 0.2 AugSeptember: 0.33 in precipitation 0.3 SepOctober: 0.68 in precipitation 0.7 OctNovember: 0.98 in precipitation 1.0 NovDecember: 1.27 in precipitation 1.3 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Kennewick, WA (4 mi away); precipitation: Kennewick 0.4 Nne, WA (within 1 mile). Daylight is calculated from latitude.

ZIP codes in Kennewick

993367b
5 to 10 °F
993377b
5 to 10 °F
993387b
5 to 10 °F

Washington planting zones →

Questions about Kennewick

What planting zone is Kennewick, WA?

Kennewick, WA is in USDA hardiness zone 7b on the 2023 map (7b: 5 to 10 °F).

When is the last frost in Kennewick, WA?

The median last spring frost is March 28 and the median first fall frost is October 30 (NOAA 1991–2020 normals, Kennewick station).

When can I plant a garden in Kennewick, WA?

Cool-season crops like peas and spinach go in around Feb 14 – Mar 7; tomatoes, peppers, beans and squash after about Apr 4, once frost risk has passed.

What kind of onions grow in Kennewick, WA?

Long-day onions: the longest day is 15 h 46 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

How much rain and snow does Kennewick, WA get?

About 8.9 inches of precipitation a year (NOAA 1991–2020 normals).