Waukesha County, in Wisconsin, sits in USDA hardiness zone 5b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
The conditions favor cabbage, cranberry, lavender, and collard greens, among others — though every individual site edits that list with its own soil, sun, and drainage.
Waukesha County lies within the Southeastern Wisconsin Lakeshore (Milwaukee Metro) — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Waukesha County holds more than one microclimate.
Soils and elevations shift across Waukesha 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 Waukesha County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Waukesha County — the short answer
Waukesha County, Wisconsin: USDA zone 5b, about 188 days between hard freezes, across 352K acres.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 16
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 21
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~188
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 352K 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 5b is Waukesha County's average, not your lot's — a low corner or a tree line moves it. Against Waukesha County's 188-day season, see what your own ground reads.
Heat in Waukesha County
Across a year, Waukesha County accumulates about 2,357 growing degree days above 50°F, about 207 more than the middle Wisconsin county — ahead of 57 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 Waukesha County
Across Waukesha County, the ground is predominantly Alfisols, where Fox, Casco, and Ozaukee are the most extensive named soil series. The soil is generally well drained with a silt loam surface. Topsoil pH runs about 6.5–7.0, neutral. Rainfall drains through hydrologic group B soils.
Soil order
Alfisols
Drainage
Well drained
Prime farmland
36%
Hydric soils
22%
Soil still varies lot by lot — soil types explained.
How the ground varies across Waukesha County
The USDA soil survey maps 44% of Waukesha County as well drained — but another 49% drains differently: 12% very poorly drained, 11% somewhat poorly drained.
Fox is the most extensive named soil at 13% of mapped acres, then Casco (9%) and Ozaukee (8%).
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 Waukesha County
Each reading below is measured for Waukesha 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 Waukesha County are well drained, in hydrologic group B — 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 Waukesha County runs about pH 6.5–7.0, close to neutral.
This is the range most vegetables prefer — one correction you probably do not have to make, which is genuinely good news for a new bed.
Keep it there with compost rather than lime or sulfur, and only amend if your own soil test says otherwise.
USDA NRCS SSURGO
Wet ground
MeasuredAbout 22% of Waukesha 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
MeasuredWaukesha County runs about 188 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 Waukesha County is in
Waukesha County sits in the Southeastern Wisconsin Till Plains — EPA Level III, inside the wider Eastern Temperate Forests. One consistent ecological setting across the whole county.
What Grows in Waukesha County
We scored all 1,086 plants against Waukesha County's own USDA zone 5b and its own 188-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 Waukesha County?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Mar 19; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 16 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 21 — 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.
Documented around Waukesha County
- Japanese beetle44 documented records
- monarch butterfly818 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Waukesha County
USGS estimates 42,097 lb of Glyphosate on Waukesha County farmland in 2019, its largest by weight, ahead of Metolachlor & Metolachlor-s (15,397 lb) and Metolachlor-s (13,621 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 Waukesha County — and how to grow with it.
We checked the federal record across Waukesha County — 3,328 documented sites across 7 of the 9 source types we track.
The most significant on record: 16 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Waukesha 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 Waukesha County
Closest first, across Waukesha County. Listing isn't leaking, and distance isn't exposure.
- PEWAUKEE CITY WATER AND SEWER UTILITYPFAS · 0.5 mi
- WK-07/19E/31-0603Nitrate · 0.9 mi
- WALGREEN CO #5466Brownfields · 0.9 mi
- Meadowbrook Corner PumpUnderground Storage Tanks · 0.9 mi
- REHABILITATION HOSPITAL OF WISCONSINBrownfields · 1.0 mi
- JANET S MILLERUnderground Storage Tanks · 1.1 mi
- WK-07/18E/36-0201Nitrate · 1.2 mi
- WK-07/18E/25-0707Nitrate · 1.4 mi
- GOLEMGESKE BROS DAIRYUnderground Storage Tanks · 1.4 mi
- WAUKESHA CNTY DEPT ENVIR RES-REC/SW DIVBrownfields · 1.5 mi
- WAUKESHA CHURCH OF CHRISTUnderground Storage Tanks · 1.6 mi
- CITY OF PEWAUKEE FIRE DEPTUnderground Storage Tanks · 1.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Waukesha 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 Waukesha County.
Sources Checked
across Waukesha County
Severity Distribution
across Waukesha County
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
Check your specific parcel in Waukesha 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 Waukesha County average
Your land is one point inside Waukesha County
Everything above resolves to Waukesha County as a whole — one PHZM band and one county frost record, read across 352K 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 Waukesha County Average
Waukesha County Average
- ●USDA Zones 5b, averaged across Waukesha County
- ●One soil character for all of Waukesha County
- ●Frost dates read at Waukesha County's scale: Apr 16 to Oct 21
YOUR Parcel
- ✓Your exact zone, not Waukesha County's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Waukesha County
Pull a site-specific report for your exact address in Waukesha County, Wisconsin — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Waukesha County averages can't show:
We read public map data around Waukesha County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Waukesha County average
How we know this about Waukesha 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 Waukesha County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Waukesha County
When does frost risk typically end in Waukesha County?
The last hard freeze (28°F) in Waukesha County typically lands around Apr 16, 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 7.
How long is the growing season in Waukesha County?
Measured between 28°F hard freezes, Waukesha County sees about 188 frost-free days — roughly Apr 16 through Oct 21, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 7 to Oct 7, about 153 days.
Is the soil safe to grow vegetables in Waukesha County?
The federal record around Waukesha County runs heavier than most — 3,328 documented sites, mostly Underground Storage Tanks entries (1,446), the nearest PFAS record about 0.5 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.
Everything above is measured at Waukesha County's scale — its 5b band and its 188-day season. Your yard writes its own version of Waukesha 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 Waukesha County’s own scale
9 of the readings below were taken at Waukesha County's own scale — its own ~188-day span between 28°F freezes, the 3 most extensive soil series mapped here and 3,328 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Waukesha County's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Waukesha County's own 28°F hard-freeze dates and its ~188-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Waukesha CountyUSDA NRCS SSURGO
- 3,328 documented contamination sites inside the county boundary, distance-sorted from its center — the closest PFAS record about 0.5 miles outFederal environmental registers
- Waukesha County's boundary and the 351,825 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~188-day seasonGrowable Ground crop-matching engine
- Waukesha County sitting wholly inside the Southeastern Wisconsin Till PlainsUS EPA Level III Ecoregions
- Open occurrence records documented in Waukesha County for 2 tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Waukesha 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 Waukesha County — the ~188 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 Waukesha County's 351,825 acreswhy one lot differs from the next →
- Which of those 3,328 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 Waukesha Countyread your own land →