Union Mills, Indiana, sits in USDA hardiness zone 5b — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Reliable performers under these conditions include cabbage, cranberry, lavender, and collard greens; what your own ground favors still comes down to its soil, sun, and drainage.
Even in Union Mills, 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 Mills 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 Mills — soil, climate, flood, and parcel records. How we handle your address.
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Union Mills — the short answer
Union Mills, Indiana: USDA zone 5b, about 199 days between hard freezes, across 388 acres of town.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 14
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 30
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~199
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 388 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 Mills's average, not your lot's — a low corner or a tree line moves it. Against Union Mills's 199-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Union Mills
Each reading below is measured for Union Mills itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredUnion Mills runs about 199 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 Mills 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 Mills is in
Union Mills sits in the Southern Michigan/Northern Indiana Drift Plains — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Union Mills's own centroid rather than borrowed from LaPorte County.
What Grows in Union Mills
Every plant below cleared Union Mills's own zone 5b and its 199-day season. Each card opens that plant's Indiana profile. How we score.
Is it too late to plant in Union Mills?
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 17; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 14 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 30 — 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.
Documented around Union Mills
Spotted lanternfly documented 17 miles from Union Mills, first recorded 2023. What to watch for.
What's on the federal record near Union Mills
Closest first, within ~10 miles of Union Mills. Listing isn't leaking, and distance isn't exposure.
- VerizonUnderground Storage Tanks · 0.8 mi
- FLATROCK ENVIR SVC INCBrownfields · 1.3 mi
- BANG UPSUnderground Storage Tanks · 1.9 mi
- FAA COMMUNICATION SITEUnderground Storage Tanks · 2.6 mi
- SOUTH CENTRAL COMMUNITY SCHOOL CORPORATIONUnderground Storage Tanks · 2.7 mi
- B & E MINI MARTUnderground Storage Tanks · 2.7 mi
- CSX TRANSPORTATIONUnderground Storage Tanks · 2.8 mi
- MINICH FARMSToxics Release Inventory · 3.2 mi
- Amerigas Propane Limited PartnershipUnderground Storage Tanks · 3.9 mi
- PERFORMIX TECHNOLOGIESToxics Release Inventory · 4.6 mi
- PLAZA 30 RESTAURANT & TRUCK STOPUnderground Storage Tanks · 4.7 mi
- KINGSBURY US ARMY RESERVE CTRBrownfields · 4.7 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Union Mills'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 Mills.
Sources Checked
within ~10 miles of Union Mills
Severity Distribution
within ~10 miles of Union Mills
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Union Mills, two things run higher than the national average within ~10 miles of Union Mills — Superfund (9 sites) and Toxics Release Inventory (37 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Check your specific parcel in Union Mills
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 Mills average
Your land is one point inside Union Mills
Everything above resolves to Union Mills as a whole — one PHZM band and one 28°F frost record, read across 388 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 Mills Average
Union Mills Average
- ●USDA Zones 5b, averaged across Union Mills
- ●One soil character for all of Union Mills
- ●Frost dates read at Union Mills's scale: Apr 14 to Oct 30
YOUR Parcel
- ✓Your exact zone, not Union Mills's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Union Mills
Pull a site-specific report for your exact address in Union Mills, Indiana — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Union Mills averages can't show:
We read public map data around Union Mills — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Union Mills average
How we know this about Union Mills
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 Mills’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 Mills
When does frost risk typically end in Union Mills?
The last hard freeze (28°F) in Union Mills typically lands around Apr 14, 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 5.
When is the first frost in Union Mills?
The first hard freeze (28°F) in Union Mills typically arrives around Oct 30, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 16, so the watching starts about Sep 30 — about 199 days after the spring freeze cleared.
How long is the growing season in Union Mills?
Measured between 28°F hard freezes, Union Mills sees about 199 frost-free days — roughly Apr 14 through Oct 30, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 5 to Oct 16, about 164 days.
Is the soil safe to grow vegetables in Union Mills?
The federal record around Union Mills is a meaningful one — 321 documented sites, mostly Underground Storage Tanks entries (179), the nearest Underground Storage Tanks record about 0.8 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.
How do I protect my plants from frost in Union Mills?
From about Sep 30 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 30 (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 30. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Union Mills's scale — its 5b band and its 199-day season. Your yard writes its own version of Union Mills'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 Mills’s own scale
7 of the readings below were taken at Union Mills's own scale — its own ~199-day season between 28°F freezes, the 388 acres it covers and 321 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Union Mills's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Union Mills's own 28°F hard-freeze dates, about Apr 14 and Oct 30 and the ~199-day span between themNOAA 1991–2020 Climate Normals
- 321 documented contamination sites on the federal record near Union Mills, the closest Underground Storage Tanks record about 0.8 miles out from the town centreFederal environmental registers
- Union Mills's boundary and the 388 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~199-day seasonGrowable Ground crop-matching engine
- The ecoregion at Union Mills's own centroid, the Southern Michigan/Northern Indiana Drift PlainsUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of Union Millslydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Union Mills's 388 acres read through its county's SSURGO summaryfrom LaPorte County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom LaPorte County
- The growing challenges every Indiana grower plans around — written at state scale, so they stay on the state guidefrom Indiana
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom LaPorte County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Union Mills's 388 acreswhy one lot differs from the next →
- Which side of Union Mills you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 388 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.8 miles 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 Mills-wide figureread your own land →