Willowbrook, Illinois, sits in USDA hardiness zone 6a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
On paper, cabbage, hazelnut, lavender, and collard greens all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Even in Willowbrook, 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 Willowbrook 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 Willowbrook — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Willowbrook — the short answer
Willowbrook, Illinois: USDA zone 6a, about 213 days between hard freezes, across 2K acres of town.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 5
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 4
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~213
- 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 6a is Willowbrook's average, not your lot's — a low corner or a tree line moves it. Against Willowbrook's 213-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Willowbrook
Each reading below is measured for Willowbrook itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredWillowbrook runs about 213 days between hard freezes — a long growing season.
There is slack for succession plantings and slow-finishing crops: many vegetables can be sown twice, and the heat-lovers have time to ripen fully.
Plan a second sowing of quick crops after the first comes out, and use the fall window most gardeners let sit idle.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredWillowbrook sits in USDA hardiness zone 6a.
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 Willowbrook is in
Willowbrook sits in the Central Corn Belt Plains — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Willowbrook's own centroid rather than borrowed from DuPage County.
What Grows in Willowbrook
Every plant below cleared Willowbrook's own zone 6a and its 213-day season. Each card opens that plant's Illinois profile. How we score.
Is it too late to plant in Willowbrook?
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 8; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 5 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 4 — long-season crops need about 90 days of runway, quick greens only 30. A long window like this one runs successions deep into fall — and even its last weeks take quick greens and garlic.
Documented around Willowbrook
Spotted lanternfly documented 9 miles from Willowbrook, first recorded 2023. What to watch for.
What's on the federal record near Willowbrook
Closest first, within ~10 miles of Willowbrook. Listing isn't leaking, and distance isn't exposure.
- Oil ExpressUnderground Storage Tanks · 1000 ft
- 38N11E-23.5e2Nitrate · 1100 ft
- PEP BOYS 1466Brownfields · 1300 ft
- Minuteman CitgoUnderground Storage Tanks · 1700 ft
- NATIONAL CONTAINER GROUPToxics Release Inventory · 1800 ft
- Kmart #4459Underground Storage Tanks · 2000 ft
- BP Gas StationUnderground Storage Tanks · 2300 ft
- PETCO STORE 2612Brownfields · 2500 ft
- AKZO CHEMICALS INCBrownfields · 2600 ft
- MIDTRONICS INCBrownfields · 0.6 mi
- MIDTRONICS INCToxics Release Inventory · 0.6 mi
- Chateau Village Living CtrUnderground Storage Tanks · 0.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Willowbrook'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 Willowbrook.
Sources Checked
within ~10 miles of Willowbrook
Severity Distribution
within ~10 miles of Willowbrook
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Willowbrook, two things run higher than the national average within ~10 miles of Willowbrook — PFAS (48 sites) and Toxics Release Inventory (264 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Check your specific parcel in Willowbrook
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 Willowbrook average
Your land is one point inside Willowbrook
Everything above resolves to Willowbrook 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 Willowbrook Average
Willowbrook Average
- ●USDA Zones 6a, averaged across Willowbrook
- ●One soil character for all of Willowbrook
- ●Frost dates read at Willowbrook's scale: Apr 5 to Nov 4
YOUR Parcel
- ✓Your exact zone, not Willowbrook's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Willowbrook
Pull a site-specific report for your exact address in Willowbrook, Illinois — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Willowbrook averages can't show:
We read public map data around Willowbrook — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Willowbrook average
How we know this about Willowbrook
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 Willowbrook’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 Willowbrook
When does frost risk typically end in Willowbrook?
The last hard freeze (28°F) in Willowbrook typically lands around Apr 5, 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 Apr 26.
When is the first frost in Willowbrook?
The first hard freeze (28°F) in Willowbrook typically arrives around Nov 4, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 21, so the watching starts about Oct 5 — about 213 days after the spring freeze cleared.
How long is the growing season in Willowbrook?
Measured between 28°F hard freezes, Willowbrook sees about 213 frost-free days — roughly Apr 5 through Nov 4, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 26 to Oct 21, about 178 days.
Is the soil safe to grow vegetables in Willowbrook?
The federal record around Willowbrook is a meaningful one — 3,534 documented sites, mostly Underground Storage Tanks entries (1,774), the nearest Underground Storage Tanks record about 0.2 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 Willowbrook?
From about Oct 5 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 Nov 4 (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 Nov 4. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Willowbrook's scale — its 6a band and its 213-day season. Your yard writes its own version of Willowbrook'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 Willowbrook’s own scale
7 of the readings below were taken at Willowbrook's own scale — its own ~213-day season between 28°F freezes, the 1,648 acres it covers and 3,534 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Willowbrook's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Willowbrook's own 28°F hard-freeze dates, about Apr 5 and Nov 4 and the ~213-day span between themNOAA 1991–2020 Climate Normals
- 3,534 documented contamination sites on the federal record near Willowbrook, the closest Underground Storage Tanks record about 0.2 miles out from the town centreFederal environmental registers
- Willowbrook's boundary and the 1,648 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~213-day seasonGrowable Ground crop-matching engine
- The ecoregion at Willowbrook's own centroid, the Central Corn Belt PlainsUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of Willowbrooklydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Willowbrook's 1,648 acres read through its county's SSURGO summaryfrom DuPage County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom DuPage 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 DuPage County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Willowbrook's 1,648 acreswhy one lot differs from the next →
- Which side of Willowbrook you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,648 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.2 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 Willowbrook-wide figureread your own land →
More in Illinois
Wider growing context
What grows across IllinoisWillowbrook sits outside our named growing regions, so Illinois as a whole is its closest context here.
Nearby growing guides