Smithton, Illinois, sits in USDA hardiness zone 7a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
A short list that earns its place here — cabbage, hazelnut, california poppy, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Even in Smithton, 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 Smithton 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 Smithton — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Smithton — the short answer
Smithton, Illinois: USDA zone 7a, about 232 days between hard freezes, across 3K acres of town.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 24
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 11
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~232
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 3K 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 7a is Smithton's average, not your lot's — a low corner or a tree line moves it. Against Smithton's 232-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Smithton
Each reading below is measured for Smithton itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredSmithton runs about 232 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
MeasuredSmithton sits in USDA hardiness zone 7a.
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 Smithton is in
Smithton sits in the Interior River Valleys and Hills — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Smithton's own centroid rather than borrowed from St. Clair County.
What Grows in Smithton
Every plant below cleared Smithton's own zone 7a and its 232-day season. Each card opens that plant's Illinois profile. How we score.
Is it too late to plant in Smithton?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Feb 24; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 24 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 11 — 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.
Documented around Smithton
Survey cells within 31 miles of Smithton checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 240 miles off. What to watch for.
What's on the federal record near Smithton
Closest first, within ~10 miles of Smithton. Listing isn't leaking, and distance isn't exposure.
- Mertz BillUnderground Storage Tanks · 850 ft
- Caseys General StoreUnderground Storage Tanks · 850 ft
- DOLLAR GENERAL STORE 6963Brownfields · 1300 ft
- Industrial Roller CoUnderground Storage Tanks · 1300 ft
- INDUSTRIAL ROLLER COBrownfields · 1300 ft
- B & J MarketUnderground Storage Tanks · 1300 ft
- SMITHTON, VILLAGE OFBrownfields · 1900 ft
- Smithton Township Road DistUnderground Storage Tanks · 2200 ft
- Hy-Dac Rubber Mfg DivUnderground Storage Tanks · 0.6 mi
- HY-DACBrownfields · 0.6 mi
- Smithton PlazaUnderground Storage Tanks · 0.7 mi
- Stehls Trenching ServiceUnderground Storage Tanks · 0.7 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Smithton'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 Smithton.
Total Sites
469
within ~10 miles of Smithton
Risk Level
Elevated
Highest-severity
2 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Smithton
Severity Distribution
within ~10 miles of Smithton
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
Check your specific parcel in Smithton
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 Smithton average
Your land is one point inside Smithton
Everything above resolves to Smithton as a whole — one PHZM band and one 28°F frost record, read across 3K 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 Smithton Average
Smithton Average
- ●USDA Zones 7a, averaged across Smithton
- ●One soil character for all of Smithton
- ●Frost dates read at Smithton's scale: Mar 24 to Nov 11
YOUR Parcel
- ✓Your exact zone, not Smithton's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Smithton
Pull a site-specific report for your exact address in Smithton, Illinois — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Smithton averages can't show:
We read public map data around Smithton — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Smithton average
How we know this about Smithton
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 Smithton’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 Smithton
When does frost risk typically end in Smithton?
The last hard freeze (28°F) in Smithton typically lands around Mar 24, 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 14.
When is the first frost in Smithton?
The first hard freeze (28°F) in Smithton typically arrives around Nov 11, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 28, so the watching starts about Oct 12 — about 232 days after the spring freeze cleared.
How long is the growing season in Smithton?
Measured between 28°F hard freezes, Smithton sees about 232 frost-free days — roughly Mar 24 through Nov 11, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 14 to Oct 28, about 197 days.
Is the soil safe to grow vegetables in Smithton?
The federal record around Smithton is a meaningful one — 469 documented sites, mostly Underground Storage Tanks entries (283), 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 Smithton?
From about Oct 12 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 11 (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 11. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Smithton's scale — its 7a band and its 232-day season. Your yard writes its own version of Smithton'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 Smithton’s own scale
7 of the readings below were taken at Smithton's own scale — its own ~232-day season between 28°F freezes, the 2,886 acres it covers and 469 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Smithton's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Smithton's own 28°F hard-freeze dates, about Mar 24 and Nov 11 and the ~232-day span between themNOAA 1991–2020 Climate Normals
- 469 documented contamination sites on the federal record near Smithton, the closest Underground Storage Tanks record about 0.2 miles out from the town centreFederal environmental registers
- Smithton's boundary and the 2,886 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~232-day seasonGrowable Ground crop-matching engine
- The ecoregion at Smithton's own centroid, the Interior River Valleys and HillsUS EPA Level III Ecoregions
- Lanternfly survey cells around Smithton checked, none carrying a detectionlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Smithton's 2,886 acres read through its county's SSURGO summaryfrom St. Clair County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom St. Clair 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 St. Clair County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Smithton's 2,886 acreswhy one lot differs from the next →
- Which side of Smithton you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 2,886 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 Smithton-wide figureread your own land →
More in Illinois
Wider growing context
What grows across IllinoisSmithton sits outside our named growing regions, so Illinois as a whole is its closest context here.
Nearby growing guides