Dupo, Illinois, sits in USDA hardiness zone 7a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Well-matched crops include cabbage, hazelnut, california poppy, 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 Dupo, 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 Dupo 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 Dupo — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Dupo — the short answer
Dupo, Illinois: USDA zone 7a, about 234 days between hard freezes, across 4K acres of town.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 22
- 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
- ~234
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 4K 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 Dupo's average, not your lot's — a low corner or a tree line moves it. Against Dupo's 234-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Dupo
Each reading below is measured for Dupo itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredDupo runs about 234 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
MeasuredDupo 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 Dupo is in
Dupo sits in the Interior River Valleys and Hills — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Dupo's own centroid rather than borrowed from St. Clair County.
What Grows in Dupo
Every plant below cleared Dupo's own zone 7a and its 234-day season. Each card opens that plant's Illinois profile. How we score.
Is it too late to plant in Dupo?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Feb 22; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 22 (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. Here the season winds down slowly: late sowings, a real autumn harvest, and garlic in the ground before the first hard freeze.
Documented around Dupo
Survey cells within 31 miles of Dupo checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 248 miles off. What to watch for.
What's on the federal record near Dupo
Closest first, within ~10 miles of Dupo. Listing isn't leaking, and distance isn't exposure.
- UNION PACIFIC RR DUPO FACILITYBrownfields · 1500 ft
- Dupo Fire Prot DistUnderground Storage Tanks · 1800 ft
- Hucks #310Underground Storage Tanks · 2200 ft
- STERLING PHARMACEUTICAL SERVICE LLCBrownfields · 2400 ft
- VERTEX CHEMICAL CORPToxics Release Inventory · 0.5 mi
- HAWKINS INC DBA VERTEX CHEMICAL CORPToxics Release Inventory · 0.5 mi
- Sugar Loaf Township Rd DistUnderground Storage Tanks · 0.6 mi
- Dupo School Dist #196Underground Storage Tanks · 0.6 mi
- KNJ Liquor and LotteryUnderground Storage Tanks · 0.6 mi
- Union Pacific Railroad Dupo YardUnderground Storage Tanks · 0.6 mi
- UP TRAIN DERAILMENTSuperfund · 0.6 mi
- PETRA COLOR INCBrownfields · 0.7 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Dupo'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 Dupo.
Sources Checked
within ~10 miles of Dupo
Severity Distribution
within ~10 miles of Dupo
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Dupo, two things run higher than the national average within ~10 miles of Dupo — Superfund (58 sites) and Toxics Release Inventory (195 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.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Check your specific parcel in Dupo
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 Dupo average
Your land is one point inside Dupo
Everything above resolves to Dupo as a whole — one PHZM band and one 28°F frost record, read across 4K 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 Dupo Average
Dupo Average
- ●USDA Zones 7a, averaged across Dupo
- ●One soil character for all of Dupo
- ●Frost dates read at Dupo's scale: Mar 22 to Nov 11
YOUR Parcel
- ✓Your exact zone, not Dupo's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Dupo
Pull a site-specific report for your exact address in Dupo, Illinois — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Dupo averages can't show:
We read public map data around Dupo — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Dupo average
How we know this about Dupo
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 Dupo’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 Dupo
When does frost risk typically end in Dupo?
The last hard freeze (28°F) in Dupo typically lands around Mar 22, 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 12.
When is the first frost in Dupo?
The first hard freeze (28°F) in Dupo 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 234 days after the spring freeze cleared.
How long is the growing season in Dupo?
Measured between 28°F hard freezes, Dupo sees about 234 frost-free days — roughly Mar 22 through Nov 11, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 12 to Oct 28, about 199 days.
Is the soil safe to grow vegetables in Dupo?
The federal record around Dupo is a meaningful one — 2,710 documented sites, mostly Underground Storage Tanks entries (1,650), the nearest Brownfields record about 0.3 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 Dupo?
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 Dupo's scale — its 7a band and its 234-day season. Your yard writes its own version of Dupo'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 Dupo’s own scale
7 of the readings below were taken at Dupo's own scale — its own ~234-day season between 28°F freezes, the 4,098 acres it covers and 2,710 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Dupo's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Dupo's own 28°F hard-freeze dates, about Mar 22 and Nov 11 and the ~234-day span between themNOAA 1991–2020 Climate Normals
- 2,710 documented contamination sites on the federal record near Dupo, the closest Brownfields record about 0.3 miles out from the town centreFederal environmental registers
- Dupo's boundary and the 4,098 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~234-day seasonGrowable Ground crop-matching engine
- The ecoregion at Dupo's own centroid, the Interior River Valleys and HillsUS EPA Level III Ecoregions
- Lanternfly survey cells around Dupo 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 Dupo's 4,098 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 Dupo's 4,098 acreswhy one lot differs from the next →
- Which side of Dupo you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 4,098 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.3 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 Dupo-wide figureread your own land →
More in Illinois
Wider growing context
What grows across IllinoisDupo sits outside our named growing regions, so Illinois as a whole is its closest context here.
Nearby growing guides