Thomasboro, Illinois, sits in USDA hardiness zone 6a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
A short list that earns its place here — cabbage, hazelnut, lavender, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Even in Thomasboro, 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 Thomasboro 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 Thomasboro — soil, climate, flood, and parcel records. How we handle your address.
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Thomasboro — the short answer
Thomasboro, Illinois: USDA zone 6a, about 208 days between hard freezes, across 640 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)
- Oct 30
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~208
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 640 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 Thomasboro's average, not your lot's — a low corner or a tree line moves it. Against Thomasboro's 208-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Thomasboro
Each reading below is measured for Thomasboro itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredThomasboro runs about 208 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
MeasuredThomasboro 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 Thomasboro is in
Thomasboro sits in the Central Corn Belt Plains — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Thomasboro's own centroid rather than borrowed from Champaign County.
What Grows in Thomasboro
Every plant below cleared Thomasboro's own zone 6a and its 208-day season. Each card opens that plant's Illinois profile. How we score.
Is it too late to plant in Thomasboro?
Almost never — the real question is what to plant next. 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 Oct 30 — 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 Thomasboro
Closest first, within ~10 miles of Thomasboro. Listing isn't leaking, and distance isn't exposure.
- Illini Fs IncUnderground Storage Tanks · 550 ft
- Thomasboro Gas StationUnderground Storage Tanks · 750 ft
- Alltel Il IncUnderground Storage Tanks · 900 ft
- Thomasboro School Dist 130Underground Storage Tanks · 1500 ft
- ALTAMONT COBrownfields · 1600 ft
- Rantoul Township Road DistUnderground Storage Tanks · 1600 ft
- Immanuel Lutheran ChurchUnderground Storage Tanks · 1600 ft
- Casey's General Store #1492Underground Storage Tanks · 2000 ft
- Royal Crown Bottling CoUnderground Storage Tanks · 2300 ft
- Thomasboro Village OfUnderground Storage Tanks · 2300 ft
- Flatville Grade SchoolUnderground Storage Tanks · 1.1 mi
- HALLS BROSBrownfields · 1.7 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Thomasboro'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 Thomasboro.
Total Sites
555
within ~10 miles of Thomasboro
Risk Level
Elevated
Highest-severity
2 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Thomasboro
Severity Distribution
within ~10 miles of Thomasboro
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.
- •TRI facilities report what they release. Check the wind — downwind beds catch more of it.
Check your specific parcel in Thomasboro
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 Thomasboro average
Your land is one point inside Thomasboro
Everything above resolves to Thomasboro as a whole — one PHZM band and one 28°F frost record, read across 640 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 Thomasboro Average
Thomasboro Average
- ●USDA Zones 6a, averaged across Thomasboro
- ●One soil character for all of Thomasboro
- ●Frost dates read at Thomasboro's scale: Apr 5 to Oct 30
YOUR Parcel
- ✓Your exact zone, not Thomasboro's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Thomasboro
Pull a site-specific report for your exact address in Thomasboro, Illinois — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Thomasboro averages can't show:
We read public map data around Thomasboro — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Thomasboro average
How we know this about Thomasboro
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 Thomasboro’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 Thomasboro
When does frost risk typically end in Thomasboro?
The last hard freeze (28°F) in Thomasboro 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 Thomasboro?
The first hard freeze (28°F) in Thomasboro typically arrives around Oct 30, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 16, so the watching starts about Sep 30 — about 208 days after the spring freeze cleared.
How long is the growing season in Thomasboro?
Measured between 28°F hard freezes, Thomasboro sees about 208 frost-free days — roughly Apr 5 through Oct 30, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 26 to Oct 16, about 173 days.
Is the soil safe to grow vegetables in Thomasboro?
The federal record around Thomasboro is a meaningful one — 555 documented sites, mostly Underground Storage Tanks entries (292), 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 Thomasboro?
From about Sep 30 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 30 (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 30. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Thomasboro's scale — its 6a band and its 208-day season. Your yard writes its own version of Thomasboro'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 Thomasboro’s own scale
6 of the readings below were taken at Thomasboro's own scale — its own ~208-day season between 28°F freezes, the 640 acres it covers and 555 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Thomasboro's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Thomasboro's own 28°F hard-freeze dates, about Apr 5 and Oct 30 and the ~208-day span between themNOAA 1991–2020 Climate Normals
- 555 documented contamination sites on the federal record near Thomasboro, the closest Underground Storage Tanks record about 0.1 miles out from the town centreFederal environmental registers
- Thomasboro's boundary and the 640 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~208-day seasonGrowable Ground crop-matching engine
- The ecoregion at Thomasboro's own centroid, the Central Corn Belt PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Thomasboro's 640 acres read through its county's SSURGO summaryfrom Champaign County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Champaign 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 Champaign County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Thomasboro's 640 acreswhy one lot differs from the next →
- Which side of Thomasboro you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 640 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 Thomasboro-wide figureread your own land →
More in Illinois
Wider growing context
What grows across IllinoisThomasboro sits outside our named growing regions, so Illinois as a whole is its closest context here.