Union Grove, Wisconsin, sits in USDA hardiness zone 5b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
A short list that earns its place here — cabbage, cranberry, lavender, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Even in Union Grove, no two yards are alike.
A low spot, a south-facing slope, or a stand of trees moves the frost date and sun across a single Union Grove lot. 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 Union Grove — soil, climate, flood, and parcel records. How we handle your address.
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Union Grove — the short answer
Union Grove, Wisconsin: USDA zone 5b, about 183 days between hard freezes, across 2K acres of town.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 20
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 20
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~183
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 2K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 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 Union Grove's average, not your lot's — a low corner or a tree line moves it. Against Union Grove's 183-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Union Grove
Each reading below is measured for Union Grove itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredUnion Grove runs about 183 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
MeasuredUnion Grove sits in USDA hardiness zone 5b.
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 Union Grove is in
Union Grove sits in the Central Corn Belt Plains — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Union Grove's own centroid, and it is not what its county reads: Racine County is mostly Southeastern Wisconsin Till Plains. The wider page above you is answering a different question about different ground.
What Grows in Union Grove
Every plant below cleared Union Grove's own zone 5b and its 183-day season. Each card opens that plant's Wisconsin profile. How we score.
Is it too late to plant in Union Grove?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Mar 23; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 20 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 20 — long-season crops need about 90 days of runway, quick greens only 30. Even past midsummer there is room for a true fall garden here, and garlic planted near the close carries the momentum into next year.
What's on the federal record near Union Grove
Closest first, within ~10 miles of Union Grove. Listing isn't leaking, and distance isn't exposure.
- VILLAGE OF UNION GROVEUnderground Storage Tanks · 450 ft
- Farmers Grain & Supply Co OpUnderground Storage Tanks · 500 ft
- GEORGES SERVICE GARAGEUnderground Storage Tanks · 650 ft
- JOHN AND GLENNS CLASSIC MOTORSBrownfields · 700 ft
- Swantz How IncUnderground Storage Tanks · 750 ft
- ASCENSION ALL SAINTS - UNION GROVEBrownfields · 800 ft
- RA-03/21E/30-0057Nitrate · 1200 ft
- UNION GROVE EXPRESS LANEUnderground Storage Tanks · 1300 ft
- Rasul Mart LLCUnderground Storage Tanks · 1400 ft
- Bob's Mobil Service IncUnderground Storage Tanks · 1600 ft
- UNION GROVE AUTO PARTS INCBrownfields · 1600 ft
- ROBERT KATTERHAGENUnderground Storage Tanks · 1700 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Union Grove'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 Union Grove.
Total Sites
704
within ~10 miles of Union Grove
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of Union Grove
Severity Distribution
within ~10 miles of Union Grove
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 Union Grove
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 Union Grove average
Your land is one point inside Union Grove
Everything above resolves to Union Grove as a whole — one PHZM band and one 28°F frost record, read across 2K 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 town 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 local average.
Your Lot vs the Union Grove Average
Union Grove Average
- ●USDA Zones 5b, averaged across Union Grove
- ●One soil character for all of Union Grove
- ●Frost dates read at Union Grove's scale: Apr 20 to Oct 20
YOUR Parcel
- ✓Your exact zone, not Union Grove's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Union Grove
Pull a site-specific report for your exact address in Union Grove, Wisconsin — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Union Grove averages can't show:
We read public map data around Union Grove — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Union Grove average
How we know this about Union Grove
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this town’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Union Grove’s own record; boundaries and acreage from US Census TIGER/Line 2025; the contamination records from the federal sources named in their beats above. Soil is not read at town grain anywhere on this page — there is no town-resolution survey in our data, which is why you will find no soil grid here rather than a statewide one wearing a local label. The resolution ledger below names every figure this page inherited.
Common questions about Union Grove
When does frost risk typically end in Union Grove?
The last hard freeze (28°F) in Union Grove typically lands around Apr 20, 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 11.
When is the first frost in Union Grove?
The first hard freeze (28°F) in Union Grove typically arrives around Oct 20, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 6, so the watching starts about Sep 20 — about 183 days after the spring freeze cleared.
How long is the growing season in Union Grove?
Measured between 28°F hard freezes, Union Grove sees about 183 frost-free days — roughly Apr 20 through Oct 20, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 11 to Oct 6, about 148 days.
Is the soil safe to grow vegetables in Union Grove?
The federal record around Union Grove is a meaningful one — 704 documented sites, mostly Underground Storage Tanks entries (372), the nearest Underground Storage Tanks record under a tenth of a mile 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.
How do I protect my plants from frost in Union Grove?
From about Sep 20 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Oct 20 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Oct 20. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Union Grove's scale — its 5b band and its 183-day season. Your yard writes its own version of Union Grove's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
What this page reads at Union Grove’s own scale
6 of the readings below were taken at Union Grove's own scale — its own ~183-day season between 28°F freezes, the 1,658 acres it covers and 704 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Union Grove's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Union Grove's own 28°F hard-freeze dates, about Apr 20 and Oct 20 and the ~183-day span between themNOAA 1991–2020 Climate Normals
- 704 documented contamination sites on the federal record near Union Grove, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Union Grove's boundary and the 1,658 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~183-day seasonGrowable Ground crop-matching engine
- Union Grove sits in the Central Corn Belt Plains — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Union Grove's 1,658 acres read through its county's SSURGO summaryfrom Racine County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Racine County
- The growing challenges every Wisconsin grower plans around — written at state scale, so they stay on the state guidefrom Wisconsin
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Racine County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Union Grove's 1,658 acreswhy one lot differs from the next →
- Which side of Union Grove you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,658 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record under a tenth of a mile out, measured from the town centrehow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — measured at your address, and averaged away by any Union Grove-wide figureread your own land →