Lake Mills, Iowa, sits in USDA hardiness zone 5a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
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 Lake 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 Lake 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 Lake Mills — soil, climate, flood, and parcel records. How we handle your address.
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Lake Mills — the short answer
Lake Mills, Iowa: USDA zone 5a, about 182 days between hard freezes, across 2K acres of city.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 18
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 17
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~182
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City 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 5a is Lake Mills's average, not your lot's — a low corner or a tree line moves it. Against Lake Mills's 182-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Lake Mills
Each reading below is measured for Lake Mills itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredLake Mills runs about 182 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
MeasuredLake Mills 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 Lake Mills is in
Lake Mills sits in the Western Corn Belt Plains — EPA Level III, inside the wider Great Plains. That is read at Lake Mills's own centroid rather than borrowed from Winnebago County.
What Grows in Lake Mills
Every plant below cleared Lake Mills's own zone 5a and its 182-day season. Each card opens that plant's Iowa profile. How we score.
Is it too late to plant in Lake Mills?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Mar 21; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 18 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 17 — long-season crops need about 90 days of runway, quick greens only 30. As the window narrows, the plantings just get faster — fall brassicas, then greens, then garlic to finish.
What's on the federal record near Lake Mills
Closest first, within ~10 miles of Lake Mills. Listing isn't leaking, and distance isn't exposure.
- JAMES RENSHAW FARMUnderground Storage Tanks · 200 ft
- MILFORD HELGESON FARMS INCUnderground Storage Tanks · 200 ft
- RONS LP GASUnderground Storage Tanks · 200 ft
- 099N23W02CCDB 25699 1979Lake Mills 3Nitrate · 500 ft
- LAKE MILLS COMMUNITY SCHOOLBrownfields · 550 ft
- COOPERATIVE SERVICES INCUnderground Storage Tanks · 800 ft
- DAVE''S 66 SERVICEUnderground Storage Tanks · 850 ft
- AGVANTAGE FS INC LAKE MILLS CARDTROLUnderground Storage Tanks · 900 ft
- 099N23W03DDD 00035 1914Lake Mills 1Nitrate · 900 ft
- NORTHERN COOP SERVICESBrownfields · 950 ft
- CASEY''S GENERAL STORE 1705Underground Storage Tanks · 950 ft
- LAKE MILLS COMM SCHOOL BUS GARAGEUnderground Storage Tanks · 1300 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Lake 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 Lake Mills.
Total Sites
58
within ~10 miles of Lake Mills
Risk Level
Moderate
Highest-severity
4 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Lake Mills
Severity Distribution
within ~10 miles of Lake Mills
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Lake Mills, Toxics Release Inventory runs higher than the national average — 4 sites within ~10 miles of Lake Mills. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Check your specific parcel in Lake 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 Lake Mills average
Your land is one point inside Lake Mills
Everything above resolves to Lake Mills 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 city 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 Lake Mills Average
Lake Mills Average
- ●USDA Zones 5a, averaged across Lake Mills
- ●One soil character for all of Lake Mills
- ●Frost dates read at Lake Mills's scale: Apr 18 to Oct 17
YOUR Parcel
- ✓Your exact zone, not Lake Mills's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Lake Mills
Pull a site-specific report for your exact address in Lake Mills, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Lake Mills averages can't show:
We read public map data around Lake Mills — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Lake Mills average
How we know this about Lake Mills
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Lake 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 city grain anywhere on this page — there is no city-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 Lake Mills
When does frost risk typically end in Lake Mills?
The last hard freeze (28°F) in Lake Mills typically lands around Apr 18, 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 9.
When is the first frost in Lake Mills?
The first hard freeze (28°F) in Lake Mills typically arrives around Oct 17, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 3, so the watching starts about Sep 17 — about 182 days after the spring freeze cleared.
How long is the growing season in Lake Mills?
Measured between 28°F hard freezes, Lake Mills sees about 182 frost-free days — roughly Apr 18 through Oct 17, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 9 to Oct 3, about 147 days.
Is the soil safe to grow vegetables in Lake Mills?
The federal record around Lake Mills shows 58 documented sites, mostly Underground Storage Tanks entries (30), the nearest Underground Storage Tanks record under a tenth of a mile out — a typical footprint for a growing area, and proximity to a documented site is information, not a diagnosis of any one yard. It's worth seeing which recorded sites sit closest to where you grow, and testing the soil before new food beds near any of them.
How do I protect my plants from frost in Lake Mills?
From about Sep 17 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 17 (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 17. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Lake Mills's scale — its 5a band and its 182-day season. Your yard writes its own version of Lake 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 Lake Mills’s own scale
6 of the readings below were taken at Lake Mills's own scale — its own ~182-day season between 28°F freezes, the 1,737 acres it covers and 58 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Lake Mills's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Lake Mills's own 28°F hard-freeze dates, about Apr 18 and Oct 17 and the ~182-day span between themNOAA 1991–2020 Climate Normals
- 58 documented contamination sites on the federal record near Lake Mills, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Lake Mills's boundary and the 1,737 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~182-day seasonGrowable Ground crop-matching engine
- The ecoregion at Lake Mills's own centroid, the Western Corn Belt PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Lake Mills's 1,737 acres read through its county's SSURGO summaryfrom Winnebago County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Winnebago County
- The growing challenges every Iowa grower plans around — written at state scale, so they stay on the state guidefrom Iowa
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Winnebago County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Lake Mills's 1,737 acreswhy one lot differs from the next →
- Which side of Lake 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 1,737 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 Lake Mills-wide figureread your own land →
More in Iowa
Wider growing context
What grows across IowaLake Mills sits outside our named growing regions, so Iowa as a whole is its closest context here.
Nearby growing guides