Prairie du Rocher, Illinois, sits in USDA hardiness zone 7a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Reliable performers under these conditions include cabbage, hazelnut, california poppy, and collard greens; what your own ground favors still comes down to its soil, sun, and drainage.
Even in Prairie du Rocher, 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 Prairie du Rocher 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 Prairie du Rocher — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Prairie du Rocher — the short answer
Prairie du Rocher, Illinois: USDA zone 7a, about 224 days between hard freezes, across 365 acres of town.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 26
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 5
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~224
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 365 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 Prairie du Rocher's average, not your lot's — a low corner or a tree line moves it. Against Prairie du Rocher's 224-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Prairie du Rocher
Each reading below is measured for Prairie du Rocher itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredPrairie du Rocher runs about 224 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
MeasuredPrairie du Rocher 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 Prairie du Rocher is in
Prairie du Rocher sits in the Interior River Valleys and Hills — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Prairie du Rocher's own centroid rather than borrowed from Randolph County.
What Grows in Prairie du Rocher
Every plant below cleared Prairie du Rocher's own zone 7a and its 224-day season. Each card opens that plant's Illinois profile. How we score.
Is it too late to plant in Prairie du Rocher?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Feb 26; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 26 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 5 — 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 Prairie du Rocher
Closest first, within ~10 miles of Prairie du Rocher. Listing isn't leaking, and distance isn't exposure.
- Klemp EugeneUnderground Storage Tanks · 750 ft
- Prairie Du Rocher StationUnderground Storage Tanks · 750 ft
- Vern's AutomotiveUnderground Storage Tanks · 1000 ft
- Braun Oil Co.Underground Storage Tanks · 1200 ft
- Prairie Du RocherUnderground Storage Tanks · 1400 ft
- Gateway FS, Inc. - Fuel 24Underground Storage Tanks · 1700 ft
- Gateway FS, Inc.Underground Storage Tanks · 1900 ft
- Maple Hollow and Stamm Hollow RdsNitrate · 3.5 mi
- Mississippi Lime CoUnderground Storage Tanks · 4.3 mi
- KINDER MORGANBrownfields · 4.9 mi
- TOWER ROCK STONE COUnderground Storage Tanks · 4.9 mi
- LHOIST NORTH AMERICA OF MISSOURI STE. GENEVIEVEToxics Release Inventory · 5.1 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Prairie du Rocher'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 Prairie du Rocher.
Total Sites
100
within ~10 miles of Prairie du Rocher
Risk Level
Moderate
Highest-severity
5 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Prairie du Rocher
Severity Distribution
within ~10 miles of Prairie du Rocher
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 Prairie du Rocher
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 Prairie du Rocher average
Your land is one point inside Prairie du Rocher
Everything above resolves to Prairie du Rocher as a whole — one PHZM band and one 28°F frost record, read across 365 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 Prairie du Rocher Average
Prairie du Rocher Average
- ●USDA Zones 7a, averaged across Prairie du Rocher
- ●One soil character for all of Prairie du Rocher
- ●Frost dates read at Prairie du Rocher's scale: Mar 26 to Nov 5
YOUR Parcel
- ✓Your exact zone, not Prairie du Rocher's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Prairie du Rocher
Pull a site-specific report for your exact address in Prairie du Rocher, Illinois — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Prairie du Rocher averages can't show:
We read public map data around Prairie du Rocher — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Prairie du Rocher average
How we know this about Prairie du Rocher
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 Prairie du Rocher’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 Prairie du Rocher
When does frost risk typically end in Prairie du Rocher?
The last hard freeze (28°F) in Prairie du Rocher typically lands around Mar 26, 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 16.
When is the first frost in Prairie du Rocher?
The first hard freeze (28°F) in Prairie du Rocher typically arrives around Nov 5, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 22, so the watching starts about Oct 6 — about 224 days after the spring freeze cleared.
How long is the growing season in Prairie du Rocher?
Measured between 28°F hard freezes, Prairie du Rocher sees about 224 frost-free days — roughly Mar 26 through Nov 5, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 16 to Oct 22, about 189 days.
Is the soil safe to grow vegetables in Prairie du Rocher?
The federal record around Prairie du Rocher shows 100 documented sites, mostly Underground Storage Tanks entries (56), the nearest Underground Storage Tanks record about 0.1 miles out — a typical footprint for a growing area, and proximity to a documented site is information, not a diagnosis of any one yard. It's worth seeing which recorded sites sit closest to where you grow, and testing the soil before new food beds near any of them.
How do I protect my plants from frost in Prairie du Rocher?
From about Oct 6 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 5 (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 5. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Prairie du Rocher's scale — its 7a band and its 224-day season. Your yard writes its own version of Prairie du Rocher'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 Prairie du Rocher’s own scale
6 of the readings below were taken at Prairie du Rocher's own scale — its own ~224-day season between 28°F freezes, the 365 acres it covers and 100 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Prairie du Rocher's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Prairie du Rocher's own 28°F hard-freeze dates, about Mar 26 and Nov 5 and the ~224-day span between themNOAA 1991–2020 Climate Normals
- 100 documented contamination sites on the federal record near Prairie du Rocher, the closest Underground Storage Tanks record about 0.1 miles out from the town centreFederal environmental registers
- Prairie du Rocher's boundary and the 365 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~224-day seasonGrowable Ground crop-matching engine
- The ecoregion at Prairie du Rocher'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 Prairie du Rocher's 365 acres read through its county's SSURGO summaryfrom Randolph County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Randolph 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 Randolph County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Prairie du Rocher's 365 acreswhy one lot differs from the next →
- Which side of Prairie du Rocher you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 365 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 Prairie du Rocher-wide figureread your own land →
More in Illinois
Wider growing context
What grows across IllinoisPrairie du Rocher sits outside our named growing regions, so Illinois as a whole is its closest context here.
Nearby growing guides