Whatcom County, in Washington, sits in USDA hardiness zone 7a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
These conditions suit cabbage, blackberry, california poppy, and collard greens — a starting list any specific site will trim or extend with its own soil, sun, and drainage.
Whatcom 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
Whatcom County holds more than one microclimate.
Soils and elevations shift across Whatcom 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 Whatcom County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Whatcom County — the short answer
Whatcom County, Washington: USDA zone 7a, about 131 days between hard freezes, across 1.3M acres.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 29
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 7
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~131
- 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 7a is Whatcom County's average, not your lot's — a low corner or a tree line moves it. Against Whatcom County's 131-day season, see what your own ground reads.
Heat in Whatcom County
Across a year, Whatcom County accumulates about 262 growing degree days above 50°F, about 1,451 fewer than the middle Washington county — no other Washington county banks fewer. 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 Whatcom County
Across Whatcom County, the ground is predominantly Andisols, where Doubtful, Whatcom, and Stetattle are the most extensive named soil series. The soil is generally well drained with a ashy silt loam surface. Topsoil pH runs about 5.0–6.0, strongly acidic. Rainfall drains through hydrologic group A soils.
Soil order
Andisols
Drainage
Well drained
Prime farmland
7%
Hydric soils
10%
Soil still varies lot by lot — soil types explained.
How the ground varies across Whatcom County
The USDA soil survey maps 56% of Whatcom County as well drained — but another 30% drains differently: 16% moderately well drained, 6% somewhat excessively drained.
Doubtful is the most extensive named soil at 6% of mapped acres, then Whatcom (4%) and Stetattle (3%).
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 Whatcom County
Each reading below is measured for Whatcom 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 Whatcom County are well drained, in hydrologic group A — ground that drains quickly.
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
MeasuredTopsoil across Whatcom County runs about pH 5.0–6.0, 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
MeasuredWhatcom County runs about 131 days between hard freezes — a short growing season.
Long-maturing crops like melons, sweet potatoes, and winter squash can run out of runway before the first hard freeze, ripening late or not at all.
Lead with fast-maturing varieties, and stretch the season on both ends with cold frames, low tunnels, or a greenhouse.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredWhatcom County sits in USDA hardiness zone 7a.
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 Whatcom County is in
Whatcom County spans 2 EPA Level III ecoregions — North Cascades (80%) and Puget Lowland (20%). 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 Whatcom County
We scored all 1,086 plants against Whatcom County's own USDA zone 7a and its own 131-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 Whatcom County?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around May 1; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 29 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 7 — long-season crops need about 90 days of runway, quick greens only 30. Short seasons reward decisiveness — quick-maturing varieties late, hardy greens under cover, and next year’s garlic in the ground before it closes.
Documented around Whatcom County
- monarch butterfly1 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Whatcom County
USGS estimates 7,288 lb of Glyphosate on Whatcom County farmland in 2019, its largest by weight, ahead of Simazine (6,063 lb) and Metolachlor-s (6,050 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 Whatcom County — and how to grow with it.
We checked the federal record across Whatcom County — 1,750 documented sites across 8 of the 9 source types we track.
The most significant on record: 13 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Whatcom 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 Whatcom County
Closest first, across Whatcom County. Listing isn't leaking, and distance isn't exposure.
- GLACIER PUBLIC SERVICE CTRUnderground Storage Tanks · 3.5 mi
- Wells Creek ProspectMining · 3.8 mi
- Wells Creek GossanMining · 4.0 mi
- Great Excelsior MineMining · 4.1 mi
- Great ExcelsiorMining · 4.1 mi
- Wells Creek Gossan ProspectMining · 4.1 mi
- Chain Lakes ProspectMining · 5.1 mi
- Glacier MineMining · 5.1 mi
- GlacierMining · 5.2 mi
- Glacier Mining Co. ClaimsMining · 5.2 mi
- NOOKSACK GEN STAUnderground Storage Tanks · 5.2 mi
- 39N/07E-08D01Nitrate · 5.5 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Whatcom 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 Whatcom County.
Severity Distribution
across Whatcom County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Whatcom County, two things run higher than the national average across Whatcom County — CAFO (116 sites) and Mining (206 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Check your specific parcel in Whatcom 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 Whatcom County average
Your land is one point inside Whatcom County
Everything above resolves to Whatcom 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 Whatcom County Average
Whatcom County Average
- ●USDA Zones 7a, averaged across Whatcom County
- ●One soil character for all of Whatcom County
- ●Frost dates read at Whatcom County's scale: May 29 to Oct 7
YOUR Parcel
- ✓Your exact zone, not Whatcom County's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Whatcom County
Pull a site-specific report for your exact address in Whatcom County, Washington — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Whatcom County averages can't show:
We read public map data around Whatcom County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Whatcom County average
How we know this about Whatcom 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 Whatcom County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Whatcom County
When does frost risk typically end in Whatcom County?
The last hard freeze (28°F) in Whatcom County typically lands around May 29, 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 Jun 19.
How long is the growing season in Whatcom County?
Measured between 28°F hard freezes, Whatcom County sees about 131 frost-free days — roughly May 29 through Oct 7, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Jun 19 to Sep 23, about 96 days.
Is the soil safe to grow vegetables in Whatcom County?
The federal record around Whatcom County runs heavier than most — 1,750 documented sites, mostly Nitrate entries (678), the nearest Underground Storage Tanks record about 3.5 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.
How do gardeners stretch the season in Whatcom County?
With about 131 frost-free days between hard freezes, Whatcom County rewards the classic extension moves: floating row cover buys roughly two to four extra weeks at each shoulder — on this season that is a working window nearer 159 to 187 days — and cold frames or low tunnels buy more. Starting transplants indoors ahead of the May 29 hard-freeze normal stretches the season without touching the calendar.
Everything above is measured at Whatcom County's scale — its 7a band and its 131-day season. Your yard writes its own version of Whatcom 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 Whatcom County’s own scale
9 of the readings below were taken at Whatcom County's own scale — its own ~131-day span between 28°F freezes, the 3 most extensive soil series mapped here and 1,750 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Whatcom County's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Whatcom County's own 28°F hard-freeze dates and its ~131-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Whatcom CountyUSDA NRCS SSURGO
- 1,750 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 3.5 miles outFederal environmental registers
- Whatcom County's boundary and the 1,349,073 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~131-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Whatcom County spans, North Cascades the largestUS EPA Level III Ecoregions
- Open occurrence records documented in Whatcom County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Whatcom 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 Whatcom County — the ~131 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 Whatcom County's 1,349,073 acreswhy one lot differs from the next →
- Which of those 1,750 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 Whatcom Countyread your own land →