Warren, Illinois, sits in USDA hardiness zone 5a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
On paper, cabbage, cranberry, lavender, and collard greens all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Even in Warren, 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 Warren 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 Warren — soil, climate, flood, and parcel records. How we handle your address.
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Warren — the short answer
Warren, Illinois: USDA zone 5a, about 185 days between hard freezes, across 661 acres of town.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 17
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 19
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~185
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 661 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 Warren's average, not your lot's — a low corner or a tree line moves it. Against Warren's 185-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Warren
Each reading below is measured for Warren itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredWarren runs about 185 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
MeasuredWarren 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 Warren is in
Warren sits in the Driftless Area — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Warren's own centroid rather than borrowed from Jo Daviess County.
What Grows in Warren
Every plant below cleared Warren's own zone 5a and its 185-day season. Each card opens that plant's Illinois profile. How we score.
Is it too late to plant in Warren?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 20; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 17 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 19 — long-season crops need about 90 days of runway, quick greens only 30. The tail of the season still works: sixty-day crops into late summer, quick greens after, garlic last of all.
What's on the federal record near Warren
Closest first, within ~10 miles of Warren. Listing isn't leaking, and distance isn't exposure.
- Warren School Dist 205Underground Storage Tanks · 400 ft
- Krupke StandardUnderground Storage Tanks · 750 ft
- Travaille Leonard CUnderground Storage Tanks · 800 ft
- Casey's General Store #1292Underground Storage Tanks · 800 ft
- Long ElecUnderground Storage Tanks · 1000 ft
- Stagecoach Fast StopUnderground Storage Tanks · 1000 ft
- Zekes Country StoreUnderground Storage Tanks · 1000 ft
- Saunders Oil Co., Inc.Underground Storage Tanks · 1200 ft
- Warren Village OfUnderground Storage Tanks · 1200 ft
- Neff Oil, Inc.Underground Storage Tanks · 1300 ft
- Brown DonaldUnderground Storage Tanks · 1300 ft
- V.S. Balbac & SonUnderground Storage Tanks · 1400 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Warren'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 Warren.
Total Sites
97
within ~10 miles of Warren
Risk Level
Moderate
Highest-severity
4 mining sites (prospects, none worked)
Sources Checked
within ~10 miles of Warren
Severity Distribution
within ~10 miles of Warren
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Warren, two things run higher than the national average within ~10 miles of Warren — CAFO (5 sites) and Underground Storage Tanks (73 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
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 Warren
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 Warren average
Your land is one point inside Warren
Everything above resolves to Warren as a whole — one PHZM band and one 28°F frost record, read across 661 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 Warren Average
Warren Average
- ●USDA Zones 5a, averaged across Warren
- ●One soil character for all of Warren
- ●Frost dates read at Warren's scale: Apr 17 to Oct 19
YOUR Parcel
- ✓Your exact zone, not Warren's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Warren
Pull a site-specific report for your exact address in Warren, Illinois — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Warren averages can't show:
We read public map data around Warren — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Warren average
How we know this about Warren
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 Warren’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 Warren
When does frost risk typically end in Warren?
The last hard freeze (28°F) in Warren typically lands around Apr 17, 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 8.
When is the first frost in Warren?
The first hard freeze (28°F) in Warren typically arrives around Oct 19, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 5, so the watching starts about Sep 19 — about 185 days after the spring freeze cleared.
How long is the growing season in Warren?
Measured between 28°F hard freezes, Warren sees about 185 frost-free days — roughly Apr 17 through Oct 19, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 8 to Oct 5, about 150 days.
Is the soil safe to grow vegetables in Warren?
The federal record around Warren shows 97 documented sites, mostly Underground Storage Tanks entries (73), 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 Warren?
From about Sep 19 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 19 (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 19. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Warren's scale — its 5a band and its 185-day season. Your yard writes its own version of Warren'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 Warren’s own scale
6 of the readings below were taken at Warren's own scale — its own ~185-day season between 28°F freezes, the 661 acres it covers and 97 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Warren's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Warren's own 28°F hard-freeze dates, about Apr 17 and Oct 19 and the ~185-day span between themNOAA 1991–2020 Climate Normals
- 97 documented contamination sites on the federal record near Warren, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Warren's boundary and the 661 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~185-day seasonGrowable Ground crop-matching engine
- The ecoregion at Warren's own centroid, the Driftless AreaUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Warren's 661 acres read through its county's SSURGO summaryfrom Jo Daviess County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Jo Daviess 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 Jo Daviess County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Warren's 661 acreswhy one lot differs from the next →
- Which side of Warren you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 661 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 Warren-wide figureread your own land →
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