Snohomish County, in Washington, sits in USDA hardiness zone 8a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
Crops well matched to these conditions include cabbage, fig, california poppy, and collard greens — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Snohomish County lies within the Pacific Northwest — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Snohomish County holds more than one microclimate.
Soils and elevations shift across Snohomish County, so your frost dates and drainage aren't the county average. 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 Snohomish County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Snohomish County — the short answer
Snohomish County, Washington: USDA zone 8a, about 208 days between hard freezes, across 1.3M acres.
- USDA zone
- 8a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 15
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Nov 9
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~208
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 1.3M acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 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 8a is Snohomish County's average, not your lot's — a low corner or a tree line moves it. Against Snohomish County's 208-day season, see what your own ground reads.
One county, several growing seasons
Snohomish County's hard-freeze record runs about 208 days between freezes — but that is the county-wide average, and several towns inside it carry a markedly different season in their own 30-year record: May Creek at about 259 days (against the county's ~208).
Those are measured records, not estimates. If you garden in one of these pockets, plant against your own town's season rather than the county's ~208-day average.
NOAA Regional Climate Centers ACIS (1991–2020), 30-year daily minimum record. Only held-out towns carrying their own record are named — a town with no record of its own is absent rather than estimated, and a county with nothing qualifying shows no spread at all.
Heat in Snohomish County
Across a year, Snohomish County accumulates about 847 growing degree days above 50°F, about 866 fewer than the middle Washington county — ahead of 3 of Washington’s 39 counties. Degree days are the heat a crop actually gets to work with — more of them is more room to ripen a long-season crop before the freeze closes the window.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in Snohomish County
Across Snohomish County, the ground is predominantly Andisols, where Tokul, Alderwood, and Elwell are the most extensive named soil series. The soil is generally moderately well drained with a gravelly medial loam surface. Topsoil pH runs about 5.3–6.1, moderately acidic. Rainfall drains through hydrologic group B soils.
Soil order
Andisols
Drainage
Moderately well drained
Prime farmland
21%
Hydric soils
13%
Soil still varies lot by lot — soil types explained.
How the ground varies across Snohomish County
The USDA soil survey maps 66% of Snohomish County as moderately well drained — but another 31% drains differently: 10% somewhat excessively drained, 10% poorly drained.
Tokul is the most extensive named soil at 24% of mapped acres, then Alderwood (16%) and Elwell (7%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in Snohomish County
Each reading below is measured for Snohomish County itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across Snohomish County are moderately well drained, in hydrologic group B — roughly the middle of the drainage range.
This is close to the middle most vegetables prefer: it holds enough water to carry a crop between rains without staying waterlogged. The catch is that a wet spring or a low corner can still tip it soggy.
Plant on the site as-is for most crops, but keep the lowest, slowest-draining beds for moisture-tolerant plantings.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Snohomish County runs about pH 5.3–6.1, on the acidic side.
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
Season length
MeasuredSnohomish County runs about 208 days between hard freezes — a long growing season.
There is slack for succession plantings and slow-finishing crops: many vegetables can be sown twice, and the heat-lovers have time to ripen fully.
Plan a second sowing of quick crops after the first comes out, and use the fall window most gardeners let sit idle.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredSnohomish County sits in USDA hardiness zone 8a.
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 Snohomish County is in
Snohomish County spans 2 EPA Level III ecoregions — North Cascades (64%) and Puget Lowland (36%). Which one your land falls in changes what grows wild there and how the ground behaves, and a county-wide answer cannot tell you which.
What Grows in Snohomish County
We scored all 1,086 plants against Snohomish County's own USDA zone 8a and its own 208-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's Washington profile.
Is it too late to plant in Snohomish County?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Mar 18; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 15 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 9 — long-season crops need about 90 days of runway, quick greens only 30. Here the season winds down slowly: late sowings, a real autumn harvest, and garlic in the ground before the first hard freeze.
Documented around Snohomish County
- monarch butterfly1 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Snohomish County
USGS estimates 4,070 lb of Glyphosate on Snohomish County farmland in 2019, its largest by weight, ahead of Metolachlor-s (2,895 lb) and Metolachlor & Metolachlor-s (2,895 lb).
Farmland across the whole county, not any one lot. Check your address for the site-by-site record.
Safe to Grow Here?
What the federal record shows across Snohomish County — and how to grow with it.
We checked the federal record across Snohomish County — 3,027 documented sites across 8 of the 9 source types we track.
The most significant on record: 12 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Snohomish County carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Snohomish County
Closest first, across Snohomish County. Listing isn't leaking, and distance isn't exposure.
- VERLOT PUBLIC SERVICE CTRUnderground Storage Tanks · 0.8 mi
- SNOHOMISH COUNTY PUBLIC WORKSUnderground Storage Tanks · 0.8 mi
- MOTOROLA INCUnderground Storage Tanks · 0.8 mi
- 30N/08E-16A01Nitrate · 2.3 mi
- GRANITE FALLS CITY OFPFAS · 2.4 mi
- GREEN GABLES GAS STOPUnderground Storage Tanks · 2.5 mi
- ConsolidatedMining · 3.2 mi
- Molly ProspectMining · 3.2 mi
- 30N/08E-08J04Nitrate · 3.4 mi
- 30N/07E-01R02Nitrate · 5.2 mi
- Bullet ProspectMining · 5.4 mi
- BulletMining · 5.4 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Snohomish County'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 Snohomish County.
Severity Distribution
across Snohomish County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Snohomish County, Mining runs higher than the national average — 594 sites across Snohomish County. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Check your specific parcel in Snohomish County
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 Snohomish County average
Your land is one point inside Snohomish County
Everything above resolves to Snohomish County as a whole — one PHZM band and one county frost record, read across 1.3M 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 county 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 county average.
Your Lot vs the Snohomish County Average
Snohomish County Average
- ●USDA Zones 8a, averaged across Snohomish County
- ●One soil character for all of Snohomish County
- ●Frost dates read at Snohomish County's scale: Apr 15 to Nov 9
YOUR Parcel
- ✓Your exact zone, not Snohomish County's 8a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Snohomish County
Pull a site-specific report for your exact address in Snohomish County, Washington — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Snohomish County averages can't show:
We read public map data around Snohomish County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Snohomish County average
How we know this about Snohomish County
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where Snohomish County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Snohomish County
When does frost risk typically end in Snohomish County?
The last hard freeze (28°F) in Snohomish County typically lands around Apr 15, 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 May 6.
How long is the growing season in Snohomish County?
Measured between 28°F hard freezes, Snohomish County sees about 208 frost-free days — roughly Apr 15 through Nov 9, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 6 to Oct 26, about 173 days.
Is the soil safe to grow vegetables in Snohomish County?
The federal record around Snohomish County runs heavier than most — 3,027 documented sites, mostly Underground Storage Tanks entries (1,145), the nearest Underground Storage Tanks record about 0.8 miles out — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
Everything above is measured at Snohomish County's scale — its 8a band and its 208-day season. Your yard writes its own version of Snohomish County's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Washington's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Snohomish County’s own scale
9 of the readings below were taken at Snohomish County's own scale — its own ~208-day span between 28°F freezes, the 3 most extensive soil series mapped here and 3,027 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Snohomish County's own USDA hardiness band, zones 8aUSDA PHZM 2023
- Snohomish County's own 28°F hard-freeze dates and its ~208-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Snohomish CountyUSDA NRCS SSURGO
- 3,027 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 0.8 miles outFederal environmental registers
- Snohomish County's boundary and the 1,335,370 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 8a and a ~208-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Snohomish County spans, North Cascades the largestUS EPA Level III Ecoregions
- Open occurrence records documented in Snohomish County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Snohomish County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Washington grower plans around — written at state scale, so they stay on the state guidefrom Washington
What this page can’t tell you
- How the season shifts across Snohomish County — the ~208 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Snohomish County's 1,335,370 acreswhy one lot differs from the next →
- Which of those 3,027 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over Snohomish Countyread your own land →