Clarendon Hills, 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.
Well-matched crops include cabbage, hazelnut, lavender, and collard greens, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
Even in Clarendon Hills, 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 Clarendon Hills 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 Clarendon Hills — soil, climate, flood, and parcel records. How we handle your address.
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Clarendon Hills — the short answer
Clarendon Hills, Illinois: USDA zone 6a, about 213 days between hard freezes, across 1K 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
- 1K 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 Clarendon Hills's average, not your lot's — a low corner or a tree line moves it. Against Clarendon Hills's 213-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Clarendon Hills
Each reading below is measured for Clarendon Hills itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredClarendon Hills 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
MeasuredClarendon Hills 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 Clarendon Hills is in
Clarendon Hills sits in the Central Corn Belt Plains — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Clarendon Hills's own centroid rather than borrowed from DuPage County.
What Grows in Clarendon Hills
Every plant below cleared Clarendon Hills'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 Clarendon Hills?
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 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. Here the season winds down slowly: late sowings, a real autumn harvest, and garlic in the ground before the first hard freeze.
Documented around Clarendon Hills
Spotted lanternfly documented 8 miles from Clarendon Hills, first recorded 2023. What to watch for.
What's on the federal record near Clarendon Hills
Closest first, within ~10 miles of Clarendon Hills. Listing isn't leaking, and distance isn't exposure.
- Public Works GarageUnderground Storage Tanks · 550 ft
- CLARENDON HILLS POLICE DEPTBrownfields · 700 ft
- Ahw ConstructionUnderground Storage Tanks · 900 ft
- Yard 44Underground Storage Tanks · 1300 ft
- Avenue 66 ServiceUnderground Storage Tanks · 1300 ft
- Hinsdale Auto RepairUnderground Storage Tanks · 1400 ft
- Keller Family TrustUnderground Storage Tanks · 1500 ft
- CLARENDON HILLSPFAS · 1500 ft
- Prairie Path Water Co. - ClarendonPFAS · 1500 ft
- Concrete Specialties CoUnderground Storage Tanks · 1700 ft
- Hinsdale Golf ClubUnderground Storage Tanks · 1800 ft
- AR SUPPLY INCBrownfields · 1900 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Clarendon Hills'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 Clarendon Hills.
Total Sites
4,105
within ~10 miles of Clarendon Hills
Risk Level
Elevated
Highest-severity
30 Superfund sites
Sources Checked
within ~10 miles of Clarendon Hills
Severity Distribution
within ~10 miles of Clarendon Hills
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Clarendon Hills, two things run higher than the national average within ~10 miles of Clarendon Hills — PFAS (49 sites) and Toxics Release Inventory (345 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 Clarendon Hills
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 Clarendon Hills average
Your land is one point inside Clarendon Hills
Everything above resolves to Clarendon Hills as a whole — one PHZM band and one 28°F frost record, read across 1K 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 Clarendon Hills Average
Clarendon Hills Average
- ●USDA Zones 6a, averaged across Clarendon Hills
- ●One soil character for all of Clarendon Hills
- ●Frost dates read at Clarendon Hills's scale: Apr 5 to Nov 4
YOUR Parcel
- ✓Your exact zone, not Clarendon Hills's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Clarendon Hills
Pull a site-specific report for your exact address in Clarendon Hills, Illinois — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Clarendon Hills averages can't show:
We read public map data around Clarendon Hills — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Clarendon Hills average
How we know this about Clarendon Hills
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 Clarendon Hills’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 Clarendon Hills
When does frost risk typically end in Clarendon Hills?
The last hard freeze (28°F) in Clarendon Hills 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 Clarendon Hills?
The first hard freeze (28°F) in Clarendon Hills 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 Clarendon Hills?
Measured between 28°F hard freezes, Clarendon Hills 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 Clarendon Hills?
The federal record around Clarendon Hills is a meaningful one — 4,105 documented sites, mostly Underground Storage Tanks entries (2,027), the nearest Underground Storage Tanks record about 0.1 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 Clarendon Hills?
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 Clarendon Hills's scale — its 6a band and its 213-day season. Your yard writes its own version of Clarendon Hills'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 Clarendon Hills’s own scale
7 of the readings below were taken at Clarendon Hills's own scale — its own ~213-day season between 28°F freezes, the 1,158 acres it covers and 4,105 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Clarendon Hills's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Clarendon Hills's own 28°F hard-freeze dates, about Apr 5 and Nov 4 and the ~213-day span between themNOAA 1991–2020 Climate Normals
- 4,105 documented contamination sites on the federal record near Clarendon Hills, the closest Underground Storage Tanks record about 0.1 miles out from the town centreFederal environmental registers
- Clarendon Hills's boundary and the 1,158 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 Clarendon Hills's own centroid, the Central Corn Belt PlainsUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of Clarendon Hillslydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Clarendon Hills's 1,158 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 Clarendon Hills's 1,158 acreswhy one lot differs from the next →
- Which side of Clarendon Hills you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,158 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.1 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 Clarendon Hills-wide figureread your own land →
More in Illinois
Wider growing context
What grows across IllinoisClarendon Hills sits outside our named growing regions, so Illinois as a whole is its closest context here.
Nearby growing guides