The Lower Columbia / Southwest Washington (Vancouver-Longview) spans USDA hardiness zone 8b — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Washington's warmest, longest-season lowland — the Washington side of the Portland/Willamette climate, not the cooler Puget Sound. All three lower-Columbia counties sit in Zone 8b with 217-251 frost-free days: Cowlitz (Longview-Kelso) runs about 251, Wahkiakum (Cathlamet) about 249, and Clark (Vancouver) about 217, with last frost around late March and first frost into early-to-mid November (county centroid data, api/data/county_data.json). That extra warmth and season length is a real difference from the shorter-season Puget lowlands to the north: growers here can push heat-loving crops — tomatoes, peppers, melons, winter squash — and get earlier spring plantings in, rather than being folded into the broad Pacific Northwest average. The corridor's variation is honest, too — the 8b figures describe the river-valley floor around Vancouver, Longview, and Cathlamet, while the surrounding Coast Range and Cascade foothills run cooler and shorter. Among the crops suited to this profile: kale, potato, garlic, and western red cedar. The site-level story — soil, sun, drainage — decides the rest.
The Lower Columbia / Southwest Washington (Vancouver-Longview) spans Washington.
Your yard isn't all of the Lower Columbia / Southwest Washington (Vancouver-Longview).
The Lower Columbia / Southwest Washington (Vancouver-Longview) spans USDA zones 8b, but your parcel sits in exactly one — and slope, tree cover, and low spots nudge it further. 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 Lower Columbia / Southwest Washington (Vancouver-Longview) — soil, climate, flood, and parcel records. How we handle your address.
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The Lower Columbia / Southwest Washington (Vancouver-Longview) — the short answer
The Lower Columbia / Southwest Washington (Vancouver-Longview): USDA zones 8b, 217–251 frost-free days depending where in it you stand, in Washington.
- USDA zones
- 8b
- USDA PHZM 2023, aggregated over the footprint
- Shortest season here
- 217 days
- NOAA Regional Climate Centers ACIS, 1991-2020 — Clark County
- Counties
- 3
- US Census TIGER/Line 2025
- Region type
- County cluster
- Growable Ground growing-region registry
Region boundary: Growable Ground growing-region registry — curated county clusters, EPA Level III ecoregions, and town clusters drawn finer than any county. The season figure is this region's own record, measured across its 3 member counties, not a state or national average.
Hardiness Zone Range
The Lower Columbia / Southwest Washington (Vancouver-Longview) is not one growing season
One answer for the Lower Columbia / Southwest Washington (Vancouver-Longview) averages 3 counties whose growing seasons are 34 days apart — from 217 frost-free days in Clark County to 251 in Cowlitz County. That is the same region, measured the same way, in the same years. Which end of it your land sits nearer decides what finishes before the first hard freeze.
The middle half of 3 counties runs 233–250 days, with a median of 249 days — a 34-day span end to end.
Measured across 3 member counties, each carrying its own 28°F normal. NOAA Regional Climate Centers ACIS, 1991-2020. A member with no own record is absent from the range rather than counted as zero — nothing here is interpolated to the region. Your own site sits somewhere inside this range; a parcel report resolves where.
Where the line runs inside the Lower Columbia / Southwest Washington (Vancouver-Longview)
The middle half of the Lower Columbia / Southwest Washington (Vancouver-Longview) runs 233–250 frost-free days, and 2 of its 3 counties sit outside that — 1 on the short side, 1 on the long. A regional planting date describes the middle well and the ends poorly, which is worth knowing before you follow one.
Under 233 frost-free days
1 county
- Clark County · 217 days
The end of the region that sets the planting calendar — start seed indoors here and the season stretches to meet the crop.
233–250 frost-free days
1 county
0 of 1 shown
The middle half of the region, and the part a single regional season describes well.
Over 250 frost-free days
1 county
- Cowlitz County · 251 days
Long enough for a second succession of a quick crop after the first comes out.
Each county is placed by its OWN 28°F frost-free normal (NOAA Regional Climate Centers ACIS, 1991-2020), the same figure its own guide page publishes. Elevation, slope and cold-air drainage move a site within its county as well — which is the part only your address resolves.
What Grows in the Lower Columbia / Southwest Washington (Vancouver-Longview)
Plants matched to the Lower Columbia / Southwest Washington (Vancouver-Longview)'s USDA zones 8b, ordered by how much hardiness margin each has across the region — the ones with room to spare at both ends of this band lead. Each links to its full growing profile.
Native Plants of the Lower Columbia / Southwest Washington (Vancouver-Longview)
Plants the USDA PLANTS Database documents as native and present in this region’s state, kept only where the published hardiness range meets the Lower Columbia / Southwest Washington (Vancouver-Longview)’s USDA zones 8b — closest range match first. Presence is recorded by state, so a plant can be documented across the state and still be scarce in your corner of the region.
The ground across the Lower Columbia / Southwest Washington (Vancouver-Longview)
The USDA soil survey maps this ground county by county. These are those records weighted by land area across three member counties — this region’s own profile, not a state figure.
The ground is predominantly Andisols, at 32% of mapped acres, followed by Ultisols (29%), Inceptisols (15%) and Mollisols (8%). Eight soil orders appear somewhere inside the footprint, which is the honest reason a regional soil answer only goes so far. The most extensive named soils are Olympic, Hazeldell, and Cinebar.
79% of those acres are well drained, and another 8% moderately well drained, 4% poorly drained. Topsoil pH runs 4.6–6.1 between the lowest and the highest county on record. 12% of the footprint is classed prime farmland.
Soil order
Andisols
Drainage
Well drained
Topsoil pH
4.6–6.1
Hydric soils
6%
Soil changes across a driveway, so which of these your own ground sits on is a parcel question rather than a regional one. Clark County holds the most wetland ground here, at 9% — soil types explained.
USDA NRCS SSURGO via Soil Data Access
What this means for growing in the Lower Columbia / Southwest Washington (Vancouver-Longview)
The soil survey reads this ground county by county, and the readings above are those records summed across the Lower Columbia / Southwest Washington (Vancouver-Longview). Here is what they mean for a garden here — and the move an experienced grower makes about each one.
Drainage
From county records79% of the mapped acres across the Lower Columbia / Southwest Washington (Vancouver-Longview) are well drained — ground that drains quickly. That is area-weighted across all three of its mapped counties.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
From county recordsTopsoil across the Lower Columbia / Southwest Washington (Vancouver-Longview) runs pH 4.6–6.1 — acidic in all three of them.
Blueberries, potatoes, and rhododendrons thrive in it, but most vegetables start locking out nutrients below about pH 6.0 and grow pale and stunted no matter how much you feed them.
A measured lime application raises pH for the crops that need it — but test first, because the right rate depends on your own soil, not the county average.
USDA NRCS SSURGO
Safe to Grow Here?
What the federal record shows across the Lower Columbia / Southwest Washington (Vancouver-Longview) — and how to grow with it.
Across the Lower Columbia / Southwest Washington (Vancouver-Longview)'s 3 counties the federal record holds 1,608 documented sites, mostly Underground Storage Tanks (1,012), Brownfields (357) and Toxics Release Inventory (112). The heaviest single county is Clark County, with 1,068.
That is a regional count, not a reading of any one lot — proximity to a documented site is information, not a diagnosis. Open the map outlined to the Lower Columbia / Southwest Washington (Vancouver-Longview) to see which records sit where you actually grow.
Sources Checked
Summed across the 3 counties in the Lower Columbia / Southwest Washington (Vancouver-Longview)
A note from Gnorman
What an experienced grower watches for around here
In and around the Lower Columbia / Southwest Washington (Vancouver-Longview), two things run higher than the national average across the 3 counties in the Lower Columbia / Southwest Washington (Vancouver-Longview) — Toxics Release Inventory (112 sites) and Underground Storage Tanks (1,012 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Your land is one point inside the Lower Columbia / Southwest Washington (Vancouver-Longview)
Everything above resolves to the Lower Columbia / Southwest Washington (Vancouver-Longview) as a whole — a footprint whose own counties record seasons 34 days apart, and hardiness across zones 8b. Your parcel sits at one point in that range, not in the middle of it. 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 region 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 regional average.
Your Lot vs the Lower Columbia / Southwest Washington (Vancouver-Longview) Average
Lower Columbia / Southwest Washington (Vancouver-Longview) Average
- ●USDA Zones 8b, averaged across Lower Columbia / Southwest Washington (Vancouver-Longview)
- ●One soil character for all of Lower Columbia / Southwest Washington (Vancouver-Longview)
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not Lower Columbia / Southwest Washington (Vancouver-Longview)'s 8b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in the Lower Columbia / Southwest Washington (Vancouver-Longview)
Pull a site-specific report for your exact address in the Lower Columbia / Southwest Washington (Vancouver-Longview) — soil, sun, drainage, frost risk, contamination, and scored plant recommendations.
Three things about your lot that Lower Columbia / Southwest Washington (Vancouver-Longview) averages can't show:
We read public map data around The Lower Columbia / Southwest Washington (Vancouver-Longview) — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Lower Columbia / Southwest Washington (Vancouver-Longview) average
How we know this about the Lower Columbia / Southwest Washington (Vancouver-Longview)
The boundary: a cluster of neighboring counties. Growing regions have no official boundary, so this footprint is our published one, and every figure on this page was measured over the counties inside it rather than borrowed from the state around it.
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, aggregated across the footprint; the growing season from NOAA Regional Climate Centers ACIS 1991–2020 28°F normals, read at each member’s own record; boundaries from US Census TIGER/Line 2025; the contamination record from the federal sources named in that beat above; the soil from the USDA NRCS SSURGO survey, read at each member county’s own record and weighted to this footprint by land area. Where a member carries no record of its own, it is absent from the figure rather than filled in.
Common questions about the Lower Columbia / Southwest Washington (Vancouver-Longview)
What hardiness zone is the Lower Columbia / Southwest Washington (Vancouver-Longview)?
The Lower Columbia / Southwest Washington (Vancouver-Longview) spans USDA hardiness zones 8b, aggregated from the USDA Agricultural Research Service Plant Hardiness Zone Map 2023 across the region's counties. Zones reflect average annual extreme minimum temperatures from 1991–2020 data.
How long is the growing season in the Lower Columbia / Southwest Washington (Vancouver-Longview)?
Measured between 28°F hard freezes, the Lower Columbia / Southwest Washington (Vancouver-Longview)'s counties mostly run 233 to 250 frost-free days, median 249 (NOAA Regional Climate Centers ACIS, 1991–2020, over 3 member counties). That 17-day spread is the honest read — no single season describes 3 counties, and each county guide below carries its own.
When does frost risk end in the Lower Columbia / Southwest Washington (Vancouver-Longview)?
Across the Lower Columbia / Southwest Washington (Vancouver-Longview), the middle half of member counties see their last 28°F hard freeze between Mar 13 and Mar 21 (median Mar 13), and their first fall freeze between Nov 9 and Nov 18. Those are hard freezes, not the last light frost: tender transplants wait for about Apr 3, and elevation decides which end of a 8-day spread you garden in.
What grows well in the Lower Columbia / Southwest Washington (Vancouver-Longview)?
The Lower Columbia / Southwest Washington (Vancouver-Longview)'s conditions suit plants such as Kale, Potato, Garlic, Western Red Cedar, Grape, Apple. What actually thrives on any one site still turns on its specific soil, sun, and drainage — we score each plant against the real conditions at your address.
How is the Lower Columbia / Southwest Washington (Vancouver-Longview) defined?
The Lower Columbia / Southwest Washington (Vancouver-Longview) is defined here as a curated cluster of 3 neighboring counties that share a growing character. Growing regions have no official boundary, so this footprint is our published one — every county in it is named on this page.
Which states does the Lower Columbia / Southwest Washington (Vancouver-Longview) cover?
The Lower Columbia / Southwest Washington (Vancouver-Longview) spans Washington. Each state's full growing guide is linked on this page.
What other growing regions cover the same states?
Pacific Northwest, Columbia Basin, Puget Sound Lowlands, Columbia Gorge, Inland Northwest (Northeast Washington), and Olympic Peninsula share at least one state with the Lower Columbia / Southwest Washington (Vancouver-Longview). Growing regions overlap and interlock — a single address can sit inside more than one, which is why the precise read is always the parcel, not the region.
What this page reads at the Lower Columbia / Southwest Washington (Vancouver-Longview)’s own scale
6 of the readings below were taken at the Lower Columbia / Southwest Washington (Vancouver-Longview)'s own scale — the zone 8b band across its footprint, a median 249-day season across its 3 counties and 1,608 documented federal contamination records across its 3 counties, 1,068 of them in Clark County alone; one is borrowed from a wider read, named and linked below.
Measured here
- The USDA hardiness band 8b aggregated across all 3 counties in the footprintUSDA PHZM 2023
- The boundary itself — the 3 counties this region is curated fromGrowable Ground subregion registry
- The growing character that makes this region distinct from the states it crossesGrowable Ground subregion registry
- The 28°F season across the footprint — the middle half of its 3 counties run 233 to 250 frost-free days, median 249NOAA Regional Climate Centers ACIS, 1991-2020
- The federal contamination record over the whole footprint — 1,608 documented federal contamination records across its 3 counties, 1,068 of them in Clark County aloneEPA, USGS and USDA federal site records
- The soil order mix across the footprint — 32% Andisols, topsoil pH 4.6–6.1, area-weighted across its 3 mapped countiesUSDA NRCS SSURGO
Inherited from a wider read
- The candidate plant list — its state's curated sets, merged and filtered to zones 8bfrom Washington
What this page can’t tell you
- Which end of the 17-day range your ground sits at — 233 days at one extreme, 250 at the other, decided mostly by elevationfrost dates explained →
- Which of those soils your own ground sits on — the survey maps them county-wide, and they change across a drivewaysoil types explained →
- The soil pH, drainage, sun hours, and frost pockets on one specific lotwhy one lot differs from the next →
Explore the Lower Columbia / Southwest Washington (Vancouver-Longview)
State growing guides
Counties in this region
Other growing regions across Washington
The maritime Northwest west of the Cascade crest — mild, wet winters and dry summers behind berries, tree fruit, and lush cool-season gardens. (Union of the west-side ecoregions.)
A dry basalt plateau of loess soils in the inland Northwest where irrigation turns arid ground into apple, cherry, hop, and wine-grape country.
The maritime lowland ringing Puget Sound — EPA's Puget Lowland ecoregion across Island, Kitsap, Mason, San Juan, and Thurston counties — where mild marine winters hold USDA zones 8a-9a and a long 227-to-300-day frost-free season.
A river canyon cut through the Cascades where wet marine air gives way to high desert in forty miles — pear, cherry, and apple orchards at the west end, vineyards and dryland ground at the east.
The coldest, most continental corner of Washington. Spokane sits at USDA zone 6b, and the Colville and Selkirk highlands of Ferry and Pend Oreille counties drop to 6a — two to three zones colder than the state's maritime west side. Frost-free windows run just 167 to 202 days here, so the growing calendar leans on cold-hardy varieties, a later last-frost start, and a shorter tomato-and-pepper season than anywhere else mapped in Washington. This is NOAA's Northeastern Washington climate division (#9) — hot, dry summers and cold-snap winters across Spokane, Colville, Republic, and Newport.
The Olympic Peninsula grows in a maritime world of its own. Cooled and watered by the open Pacific and the Strait of Juan de Fuca, its four counties — Clallam, Jefferson, Grays Harbor, and Mason — hold one of the widest rainfall gradients in the contiguous U.S.: from the Hoh and Quinault temperate rainforests (140+ inches a year) to the Sequim–Dungeness rain shadow near 16 inches that made the valley North America's lavender country. Long, mild, cloud-tempered seasons (USDA zones 8a–8b) favor cool-season crops — brassicas, alliums, salad greens, hardy berries, and cider apples — over heat-lovers, and frost timing swings sharply as you climb from tidewater toward the Olympic Mountains (which is why Jefferson County reads a full zone cooler and shorter-seasoned than its coastal neighbors). This page reads the peninsula's own counties, not a Pacific-Northwest-wide average, so the season and zone figures reflect the coast you're actually standing on.