Walnut Hill, Illinois, sits in USDA hardiness zone 6b — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
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 Walnut Hill, 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 Walnut Hill 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 Walnut Hill — soil, climate, flood, and parcel records. How we handle your address.
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Walnut Hill — the short answer
Walnut Hill, Illinois: USDA zone 6b, about 218 days between hard freezes, across 243 acres of town.
- USDA zone
- 6b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 29
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 2
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~218
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 243 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 6b is Walnut Hill's average, not your lot's — a low corner or a tree line moves it. Against Walnut Hill's 218-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Walnut Hill
Each reading below is measured for Walnut Hill itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredWalnut Hill runs about 218 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
MeasuredWalnut Hill sits in USDA hardiness zone 6b.
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 Walnut Hill is in
Walnut Hill sits in the Interior River Valleys and Hills — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Walnut Hill's own centroid rather than borrowed from Marion County.
What Grows in Walnut Hill
Every plant below cleared Walnut Hill's own zone 6b and its 218-day season. Each card opens that plant's Illinois profile. How we score.
Is it too late to plant in Walnut Hill?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 1; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 29 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 2 — long-season crops need about 90 days of runway, quick greens only 30. With a season this long, “too late” mostly means “switch crops” — second sowings and a full fall garden are the norm, with garlic closing the year.
What's on the federal record near Walnut Hill
Closest first, within ~10 miles of Walnut Hill. Listing isn't leaking, and distance isn't exposure.
- RACCOON WATER COMPANYPFAS · 1.1 mi
- Raccoon Super K ShellUnderground Storage Tanks · 3.1 mi
- CMCIBrownfields · 3.2 mi
- Centralia Municipal AirportUnderground Storage Tanks · 3.7 mi
- Dix Car & Truck StopUnderground Storage Tanks · 3.8 mi
- Centralia Pepsi ColaUnderground Storage Tanks · 4.3 mi
- Centralia Township Road DeptUnderground Storage Tanks · 4.5 mi
- T. W. Associates, Inc.Underground Storage Tanks · 4.7 mi
- Meadow Woods Country ClubUnderground Storage Tanks · 4.7 mi
- AMEREN ILLINOIS CENTRALIA GAS STORAGE FIELDBrownfields · 4.8 mi
- UNITED PARCEL SERVICEBrownfields · 4.8 mi
- United Parcel SerUnderground Storage Tanks · 4.9 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Walnut Hill'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 Walnut Hill.
Sources Checked
within ~10 miles of Walnut Hill
Severity Distribution
within ~10 miles of Walnut Hill
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Walnut Hill, two things run higher than the national average within ~10 miles of Walnut Hill — Superfund (5 sites) and PFAS (3 sites). That's not a problem with your land — it's information about it.
Superfund: Superfund sites represent the most severe contamination in the federal system.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Check your specific parcel in Walnut Hill
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 Walnut Hill average
Your land is one point inside Walnut Hill
Everything above resolves to Walnut Hill as a whole — one PHZM band and one 28°F frost record, read across 243 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 Walnut Hill Average
Walnut Hill Average
- ●USDA Zones 6b, averaged across Walnut Hill
- ●One soil character for all of Walnut Hill
- ●Frost dates read at Walnut Hill's scale: Mar 29 to Nov 2
YOUR Parcel
- ✓Your exact zone, not Walnut Hill's 6b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Walnut Hill
Pull a site-specific report for your exact address in Walnut Hill, Illinois — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Walnut Hill averages can't show:
We read public map data around Walnut Hill — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Walnut Hill average
How we know this about Walnut Hill
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 Walnut Hill’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 Walnut Hill
When does frost risk typically end in Walnut Hill?
The last hard freeze (28°F) in Walnut Hill typically lands around Mar 29, 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 19.
When is the first frost in Walnut Hill?
The first hard freeze (28°F) in Walnut Hill typically arrives around Nov 2, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 19, so the watching starts about Oct 3 — about 218 days after the spring freeze cleared.
How long is the growing season in Walnut Hill?
Measured between 28°F hard freezes, Walnut Hill sees about 218 frost-free days — roughly Mar 29 through Nov 2, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 19 to Oct 19, about 183 days.
Is the soil safe to grow vegetables in Walnut Hill?
The federal record around Walnut Hill is a meaningful one — 179 documented sites, mostly Underground Storage Tanks entries (109), the nearest PFAS record about 1.1 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 Walnut Hill?
From about Oct 3 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 2 (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 2. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Walnut Hill's scale — its 6b band and its 218-day season. Your yard writes its own version of Walnut Hill'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 Walnut Hill’s own scale
6 of the readings below were taken at Walnut Hill's own scale — its own ~218-day season between 28°F freezes, the 243 acres it covers and 179 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Walnut Hill's own USDA hardiness band, zones 6bUSDA PHZM 2023
- Walnut Hill's own 28°F hard-freeze dates, about Mar 29 and Nov 2 and the ~218-day span between themNOAA 1991–2020 Climate Normals
- 179 documented contamination sites on the federal record near Walnut Hill, the closest PFAS record about 1.1 miles out from the town centreFederal environmental registers
- Walnut Hill's boundary and the 243 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6b and a ~218-day seasonGrowable Ground crop-matching engine
- The ecoregion at Walnut Hill's own centroid, the Interior River Valleys and HillsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Walnut Hill's 243 acres read through its county's SSURGO summaryfrom Marion County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Marion 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 Marion County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Walnut Hill's 243 acreswhy one lot differs from the next →
- Which side of Walnut Hill you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 243 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest PFAS record about 1.1 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 Walnut Hill-wide figureread your own land →
More in Illinois
Wider growing context
What grows across IllinoisWalnut Hill sits outside our named growing regions, so Illinois as a whole is its closest context here.
Nearby growing guides