Clark County, in Wisconsin, sits in USDA hardiness zone 4b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
The conditions favor cabbage, cranberry, turkish rocket, and collard greens, among others — though every individual site edits that list with its own soil, sun, and drainage.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Clark County holds more than one microclimate.
Soils and elevations shift across Clark 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 Clark County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Clark County — the short answer
Clark County, Wisconsin: USDA zone 4b, about 166 days between hard freezes, across 774K acres.
- USDA zone
- 4b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 27
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 10
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~166
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 774K 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 4b is Clark County's average, not your lot's — a low corner or a tree line moves it. Against Clark County's 166-day season, see what your own ground reads.
Heat in Clark County
Across a year, Clark County accumulates about 2,009 growing degree days above 50°F, about 141 fewer than the middle Wisconsin county — ahead of 23 of Wisconsin’s 72 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 Clark County
Across Clark County, the ground is predominantly Alfisols, where Loyal, Withee, and Flambeau are the most extensive named soil series. The soil is generally moderately well drained with a silt loam surface. Topsoil pH runs about 5.4–5.9, moderately acidic. Rainfall drains through hydrologic group C/D soils.
Soil order
Alfisols
Drainage
Moderately well drained
Prime farmland
32%
Hydric soils
22%
Soil still varies lot by lot — soil types explained.
How the ground varies across Clark County
The USDA soil survey maps 48% of Clark County as moderately well drained — but another 52% drains differently: 34% somewhat poorly drained, 9% very poorly drained.
Loyal is the most extensive named soil at 25% of mapped acres, then Withee (13%) and Flambeau (6%).
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 Clark County
Each reading below is measured for Clark 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 Clark County are moderately well drained, in hydrologic group C/D — 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 Clark County runs about pH 5.4–5.9, 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
Wet ground
MeasuredAbout 22% of Clark County is mapped as hydric — wetland — soil.
If your lot falls in one of those pockets, a standard in-ground bed will fight waterlogging all season, and roots that need air will struggle.
Check how your own ground drains before you dig; raised beds or moisture-loving plantings turn a wet corner from a problem into a niche.
USDA NRCS SSURGO
Season length
MeasuredClark County runs about 166 days between hard freezes — a moderate growing season.
There is room for the full run of cool-season crops plus a warm-season main crop, but the calendar is tight enough that a late spring or early fall frost still decides how much finishes.
Time warm-season transplants to your last hard freeze, and a few weeks of season extension turns a near-miss harvest into a sure one.
NOAA 1991–2020 Climate Normals
The kind of country Clark County is in
Clark County sits in the North Central Hardwood Forests — EPA Level III, inside the wider Eastern Temperate Forests. One consistent ecological setting across the whole county.
What Grows in Clark County
We scored all 1,086 plants against Clark County's own USDA zone 4b and its own 166-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 Wisconsin profile.
Is it too late to plant in Clark County?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Mar 30; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 27 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 10 — long-season crops need about 90 days of runway, quick greens only 30. The tail of the season still works: sixty-day crops into late summer, quick greens after, garlic last of all.
What gets applied to farmland in Clark County
USGS estimates 60,834 lb of Glyphosate on Clark County farmland in 2019, its largest by weight, ahead of Metolachlor & Metolachlor-s (46,094 lb) and Acetochlor (44,232 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 Clark County — and how to grow with it.
We checked the federal record across Clark County — 524 documented sites across 6 of the 9 source types we track.
The most significant on record: 1 Superfund site (none NPL-listed). Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
There's a meaningful federal record across Clark County — worth a look before you plant food, not a reason to hold back from growing. Proximity to a documented site is information, not a diagnosis of any one yard. A soil test before new food beds is the sensible precaution here, and the map shows exactly which sites sit where, so you can see what's actually near you.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Clark County
Closest first, across Clark County. Listing isn't leaking, and distance isn't exposure.
- BRUCE MOUND WINTER SPORTS AREAUnderground Storage Tanks · 1700 ft
- CK-26/02W/14-0245Nitrate · 0.7 mi
- STEWART REDVILLE DAIRYUnderground Storage Tanks · 1.6 mi
- MARSHFIELD CLINIC - GREENWOOD CENTERBrownfields · 1.6 mi
- GRASSLAND DAIRY PROD INC COOLING SOUTH PLANT-TC014Brownfields · 1.6 mi
- GRASSLAND DAIRY PROD INC COOLING SOUTH PLANT-TC014Toxics Release Inventory · 1.6 mi
- Grassland Dairy Products IncUnderground Storage Tanks · 1.6 mi
- FAMILY DOLLAR #10572Brownfields · 1.6 mi
- GREENWOOD MILK PRODUCTSBrownfields · 1.6 mi
- GREENWOOD MILK PRODUCTSToxics Release Inventory · 1.6 mi
- COOPERATIVE SERVICES INCBrownfields · 1.7 mi
- Cooperative Services Bulk PlantUnderground Storage Tanks · 1.7 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Clark 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 Clark County.
Total Sites
524
across Clark County
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
across Clark County
Severity Distribution
across Clark County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Clark County, two things run higher than the national average across Clark County — CAFO (9 sites) and Underground Storage Tanks (348 sites). That's not a problem with your land — it's information about it.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Clark 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 Clark County average
Your land is one point inside Clark County
Everything above resolves to Clark County as a whole — one PHZM band and one county frost record, read across 774K 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 Clark County Average
Clark County Average
- ●USDA Zones 4b, averaged across Clark County
- ●One soil character for all of Clark County
- ●Frost dates read at Clark County's scale: Apr 27 to Oct 10
YOUR Parcel
- ✓Your exact zone, not Clark County's 4b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Clark County
Pull a site-specific report for your exact address in Clark County, Wisconsin — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Clark County averages can't show:
We read public map data around Clark County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Clark County average
How we know this about Clark 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 Clark County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Clark County
When does frost risk typically end in Clark County?
The last hard freeze (28°F) in Clark County typically lands around Apr 27, 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 18.
How long is the growing season in Clark County?
Measured between 28°F hard freezes, Clark County sees about 166 frost-free days — roughly Apr 27 through Oct 10, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 18 to Sep 26, about 131 days.
Is the soil safe to grow vegetables in Clark County?
The federal record around Clark County is a meaningful one — 524 documented sites, mostly Underground Storage Tanks entries (348), the nearest Underground Storage Tanks record about 0.3 miles out — so a soil test before new food beds is a sensible precaution here, not a reason to hold back from growing. Remember that proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what sits where.
Everything above is measured at Clark County's scale — its 4b band and its 166-day season. Your yard writes its own version of Clark 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 Wisconsin's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Clark County’s own scale
8 of the readings below were taken at Clark County's own scale — its own ~166-day span between 28°F freezes, the 3 most extensive soil series mapped here and 524 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Clark County's own USDA hardiness band, zones 4bUSDA PHZM 2023
- Clark County's own 28°F hard-freeze dates and its ~166-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Clark CountyUSDA NRCS SSURGO
- 524 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 0.3 miles outFederal environmental registers
- Clark County's boundary and the 774,206 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 4b and a ~166-day seasonGrowable Ground crop-matching engine
- Clark County sitting wholly inside the North Central Hardwood ForestsUS EPA Level III Ecoregions
- Which agricultural compounds go onto Clark County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Wisconsin grower plans around — written at state scale, so they stay on the state guidefrom Wisconsin
What this page can’t tell you
- How the season shifts across Clark County — the ~166 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 Clark County's 774,206 acreswhy one lot differs from the next →
- Which of those 524 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 Clark Countyread your own land →