Green County, in Wisconsin, sits in USDA hardiness zone 5a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
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.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Green County holds more than one microclimate.
Soils and elevations shift across Green 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 Green County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Green County — the short answer
Green County, Wisconsin: USDA zone 5a, about 193 days between hard freezes, across 374K acres.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 12
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 22
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~193
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 374K 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 5a is Green County's average, not your lot's — a low corner or a tree line moves it. Against Green County's 193-day season, see what your own ground reads.
Heat in Green County
Across a year, Green County accumulates about 2,511 growing degree days above 50°F, about 361 more than the middle Wisconsin county — ahead of 70 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 Green County
Across Green County, the ground is predominantly Alfisols, where Newglarus, Dodgeville, and Edmund are the most extensive named soil series. The soil is generally well drained with a silt loam surface. Topsoil pH runs about 6.2–6.7, slightly acidic. Rainfall drains through hydrologic group C soils.
Soil order
Alfisols
Drainage
Well drained
Prime farmland
28%
Hydric soils
8%
Soil still varies lot by lot — soil types explained.
How the ground varies across Green County
The USDA soil survey maps 70% of Green County as well drained — but another 29% drains differently: 7% somewhat poorly drained, 7% moderately well drained.
Newglarus is the most extensive named soil at 20% of mapped acres, then Dodgeville (6%) and Edmund (4%).
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 Green County
Each reading below is measured for Green 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 Green County are well drained, in hydrologic group C — 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 Green County runs about pH 6.2–6.7, 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
Season length
MeasuredGreen County runs about 193 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
Winter hardiness
MeasuredGreen County sits in USDA hardiness zone 5a.
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 Green County is in
Green County spans 2 EPA Level III ecoregions — Southeastern Wisconsin Till Plains (60%) and Driftless Area (40%). 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 Green County
We scored all 1,086 plants against Green County's own USDA zone 5a and its own 193-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 Green County?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Mar 15; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 12 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 22 — long-season crops need about 90 days of runway, quick greens only 30. Late in the year the fall bench takes over — quick greens, radishes, and garlic that repays you next summer.
Documented around Green County
- Japanese beetle3 documented records
- monarch butterfly475 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Green County
USGS estimates 237,920 lb of Glyphosate on Green County farmland in 2019, its largest by weight, ahead of Metolachlor & Metolachlor-s (86,306 lb) and Metolachlor-s (74,460 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 Green County — and how to grow with it.
We checked the federal record across Green County — 383 documented sites across 7 of the 9 source types we track.
The most significant on record: 21 Toxics Release Inventory facilities. Active industrial facilities reporting chemical releases to air, water, and land.
There's a meaningful federal record across Green 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 Green County
Closest first, across Green County. Listing isn't leaking, and distance isn't exposure.
- GN-02/07E/02-0040Nitrate · 0.9 mi
- CHESEBRO LANDSCAPINGUnderground Storage Tanks · 1.7 mi
- NORTHERN NATURAL GAS-BELLEVILLE COMPRESSORBrownfields · 1.9 mi
- ROBERT PICKETTUnderground Storage Tanks · 2.3 mi
- Fuel-Ocity LLCUnderground Storage Tanks · 2.6 mi
- JOHN M LANGERUnderground Storage Tanks · 2.9 mi
- TRUCKS INCBrownfields · 3.0 mi
- EVERGREEN EQUIPMENT INCUnderground Storage Tanks · 3.0 mi
- MONROE TRUCK LEASE INCUnderground Storage Tanks · 3.0 mi
- DON MALKOWUnderground Storage Tanks · 3.3 mi
- JAMES ZANDERUnderground Storage Tanks · 3.6 mi
- Monroe Municipal AirportUnderground Storage Tanks · 3.8 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Green 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 Green County.
Total Sites
383
across Green County
Risk Level
Elevated
Highest-severity
21 Toxics Release Inventory facilities
Severity Distribution
across Green County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Green County, Underground Storage Tanks runs higher than the national average — 251 sites across Green County. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Green 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 Green County average
Your land is one point inside Green County
Everything above resolves to Green County as a whole — one PHZM band and one county frost record, read across 374K 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 Green County Average
Green County Average
- ●USDA Zones 5a, averaged across Green County
- ●One soil character for all of Green County
- ●Frost dates read at Green County's scale: Apr 12 to Oct 22
YOUR Parcel
- ✓Your exact zone, not Green County's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Green County
Pull a site-specific report for your exact address in Green County, Wisconsin — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Green County averages can't show:
We read public map data around Green County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Green County average
How we know this about Green 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 Green County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Green County
When does frost risk typically end in Green County?
The last hard freeze (28°F) in Green County typically lands around Apr 12, 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 3.
How long is the growing season in Green County?
Measured between 28°F hard freezes, Green County sees about 193 frost-free days — roughly Apr 12 through Oct 22, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 3 to Oct 8, about 158 days.
Is the soil safe to grow vegetables in Green County?
The federal record around Green County is a meaningful one — 383 documented sites, mostly Underground Storage Tanks entries (251), the nearest Nitrate record about 0.9 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 Green County's scale — its 5a band and its 193-day season. Your yard writes its own version of Green 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 Green County’s own scale
9 of the readings below were taken at Green County's own scale — its own ~193-day span between 28°F freezes, the 3 most extensive soil series mapped here and 383 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Green County's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Green County's own 28°F hard-freeze dates and its ~193-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Green CountyUSDA NRCS SSURGO
- 383 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Nitrate record about 0.9 miles outFederal environmental registers
- Green County's boundary and the 373,788 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~193-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Green County spans, Southeastern Wisconsin Till Plains the largestUS EPA Level III Ecoregions
- Open occurrence records documented in Green County for 2 tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Green 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 Green County — the ~193 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 Green County's 373,788 acreswhy one lot differs from the next →
- Which of those 383 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 Green Countyread your own land →