Windsor, Illinois, 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.
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 Windsor, 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 Windsor 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 Windsor — soil, climate, flood, and parcel records. How we handle your address.
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Windsor — the short answer
Windsor, Illinois: USDA zone 5b, about 199 days between hard freezes, across 280 acres of town.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 11
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 27
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~199
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 280 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 Windsor's average, not your lot's — a low corner or a tree line moves it. Against Windsor's 199-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Windsor
Each reading below is measured for Windsor itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredWindsor 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
MeasuredWindsor 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 Windsor is in
Windsor sits in the Central Corn Belt Plains — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Windsor's own centroid, and it is not what its county reads: Mercer County is mostly Interior River Valleys and Hills. The wider page above you is answering a different question about different ground.
What Grows in Windsor
Every plant below cleared Windsor's own zone 5b and its 199-day season. Each card opens that plant's Illinois profile. How we score.
Is it too late to plant in Windsor?
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 14; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 11 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 27 — 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 Windsor
Closest first, within ~10 miles of Windsor. Listing isn't leaking, and distance isn't exposure.
- New Windsor Compressor StaUnderground Storage Tanks · 300 ft
- At&T CommunicationsUnderground Storage Tanks · 300 ft
- New Windsor General StoreUnderground Storage Tanks · 400 ft
- Sams 66Underground Storage Tanks · 500 ft
- Winola Jr High SchlUnderground Storage Tanks · 1200 ft
- GobensUnderground Storage Tanks · 1500 ft
- Allen Oil Co Inc.Underground Storage Tanks · 1500 ft
- ALLEN OIL COBrownfields · 1500 ft
- ANR PIPELINE COMPRESSOR STATIONBrownfields · 0.7 mi
- SG SWINE - NEW WINDSORCAFO · 1.1 mi
- TY STEAD FARM AND WSB, LLCCAFO · 3.1 mi
- Alpha Ready Mix CorpUnderground Storage Tanks · 3.3 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Windsor'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 Windsor.
Total Sites
87
within ~10 miles of Windsor
Risk Level
Moderate
Highest-severity
1 Toxics Release Inventory facility
Sources Checked
within ~10 miles of Windsor
Severity Distribution
within ~10 miles of Windsor
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Windsor, two things run higher than the national average within ~10 miles of Windsor — CAFO (14 sites) and Underground Storage Tanks (56 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Windsor
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 Windsor average
Your land is one point inside Windsor
Everything above resolves to Windsor as a whole — one PHZM band and one 28°F frost record, read across 280 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 Windsor Average
Windsor Average
- ●USDA Zones 5b, averaged across Windsor
- ●One soil character for all of Windsor
- ●Frost dates read at Windsor's scale: Apr 11 to Oct 27
YOUR Parcel
- ✓Your exact zone, not Windsor's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Windsor
Pull a site-specific report for your exact address in Windsor, Illinois — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Windsor averages can't show:
We read public map data around Windsor — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Windsor average
How we know this about Windsor
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 Windsor’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 Windsor
When does frost risk typically end in Windsor?
The last hard freeze (28°F) in Windsor typically lands around Apr 11, 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 2.
When is the first frost in Windsor?
The first hard freeze (28°F) in Windsor typically arrives around Oct 27, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 13, so the watching starts about Sep 27 — about 199 days after the spring freeze cleared.
How long is the growing season in Windsor?
Measured between 28°F hard freezes, Windsor sees about 199 frost-free days — roughly Apr 11 through Oct 27, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 2 to Oct 13, about 164 days.
Is the soil safe to grow vegetables in Windsor?
The federal record around Windsor shows 87 documented sites, mostly Underground Storage Tanks entries (56), 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 Windsor?
From about Sep 27 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 27 (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 27. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Windsor's scale — its 5b band and its 199-day season. Your yard writes its own version of Windsor'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 Windsor’s own scale
6 of the readings below were taken at Windsor's own scale — its own ~199-day season between 28°F freezes, the 280 acres it covers and 87 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Windsor's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Windsor's own 28°F hard-freeze dates, about Apr 11 and Oct 27 and the ~199-day span between themNOAA 1991–2020 Climate Normals
- 87 documented contamination sites on the federal record near Windsor, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Windsor's boundary and the 280 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~199-day seasonGrowable Ground crop-matching engine
- Windsor 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 Windsor's 280 acres read through its county's SSURGO summaryfrom Mercer County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Mercer County
- The growing challenges every Illinois grower plans around — written at state scale, so they stay on the state guidefrom Illinois
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Mercer County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Windsor's 280 acreswhy one lot differs from the next →
- Which side of Windsor you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 280 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 Windsor-wide figureread your own land →
More in Illinois
Wider growing context
What grows across IllinoisWindsor sits outside our named growing regions, so Illinois as a whole is its closest context here.