Monroe County, in 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.
Crops well matched to these conditions include cabbage, hazelnut, california poppy, and collard greens — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Monroe County holds more than one microclimate.
Soils and elevations shift across Monroe County, so your frost dates and drainage aren't the county average. 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 Monroe County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Monroe County — the short answer
Monroe County, Illinois: USDA zone 7a, about 235 days between hard freezes, across 247K acres.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 24
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Nov 14
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~235
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 247K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 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 Monroe County's average, not your lot's — a low corner or a tree line moves it. Against Monroe County's 235-day season, see what your own ground reads.
Heat in Monroe County
Across a year, Monroe County accumulates about 4,012 growing degree days above 50°F, about 629 more than the middle Illinois county — ahead of 92 of Illinois’s 102 counties. Degree days are the heat a crop actually gets to work with — more of them is more room to ripen a long-season crop before the freeze closes the window.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in Monroe County
Across Monroe County, the ground is predominantly Alfisols, where Menfro, Bunkum, and Homen are the most extensive named soil series. The soil is generally well drained with a silt loam surface. Topsoil pH runs about 6.2–6.5, slightly acidic. Rainfall drains through hydrologic group B soils.
Soil order
Alfisols
Drainage
Well drained
Prime farmland
25%
Hydric soils
17%
Soil still varies lot by lot — soil types explained.
How the ground varies across Monroe County
The USDA soil survey maps 35% of Monroe County as well drained — but another 62% drains differently: 31% somewhat poorly drained, 14% moderately well drained.
Menfro is the most extensive named soil at 19% of mapped acres, then Bunkum (11%) and Homen (7%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in Monroe County
Each reading below is measured for Monroe County itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across Monroe County are well drained, in hydrologic group B — ground that drains quickly.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Monroe County runs about pH 6.2–6.5, close to neutral.
This is the range most vegetables prefer — one correction you probably do not have to make, which is genuinely good news for a new bed.
Keep it there with compost rather than lime or sulfur, and only amend if your own soil test says otherwise.
USDA NRCS SSURGO
Wet ground
MeasuredAbout 17% of Monroe County is mapped as hydric — wetland — soil.
If your lot falls in one of those pockets, a standard in-ground bed will fight waterlogging all season, and roots that need air will struggle.
Check how your own ground drains before you dig; raised beds or moisture-loving plantings turn a wet corner from a problem into a niche.
USDA NRCS SSURGO
Season length
MeasuredMonroe County runs about 235 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
The kind of country Monroe County is in
Monroe County sits in the Interior River Valleys and Hills — EPA Level III, inside the wider Eastern Temperate Forests. One consistent ecological setting across the whole county.
What Grows in Monroe County
We scored all 1,086 plants against Monroe County's own USDA zone 7a and its own 235-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's Illinois profile.
Is it too late to plant in Monroe County?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. 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 14 — 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 Monroe County
Survey cells within 31 miles of Monroe County checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 242 miles off. What to watch for.
- monarch butterfly7 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Monroe County
USGS estimates 120,177 lb of Glyphosate on Monroe County farmland in 2019, its largest by weight, ahead of Metolachlor & Metolachlor-s (118,370 lb) and Metolachlor-s (93,032 lb).
Farmland across the whole county, not any one lot. Check your address for the site-by-site record.
Safe to Grow Here?
What the federal record shows across Monroe County — and how to grow with it.
We checked the federal record across Monroe County — 139 documented sites across 6 of the 9 source types we track.
The most significant on record: 1 Toxics Release Inventory facility. Active industrial facilities reporting chemical releases to air, water, and land.
There's a meaningful federal record across Monroe County — worth a look before you plant food, not a reason to hold back from growing. Proximity to a documented site is information, not a diagnosis of any one yard. A soil test before new food beds is the sensible precaution here, and the map shows exactly which sites sit where, so you can see what's actually near you.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Monroe County
Closest first, across Monroe County. Listing isn't leaking, and distance isn't exposure.
- SYDENSTRICKER NOBBE PARTNERSBrownfields · 2.3 mi
- IL AMERICAN-EAST ST LOUISPFAS · 2.7 mi
- WATERLOOPFAS · 2.7 mi
- VALMEYERPFAS · 2.7 mi
- FOUNTAIN WATER DISTRICTPFAS · 2.7 mi
- Bushy Prairie and Fisher RdsNitrate · 2.8 mi
- Huebner Concrete Contracting CoUnderground Storage Tanks · 2.9 mi
- Herberer EquipUnderground Storage Tanks · 3.1 mi
- KEN VALENTINE AUTOBODYBrownfields · 3.4 mi
- WHEATS AUTO BODY INCBrownfields · 3.5 mi
- Koerber Dist CoUnderground Storage Tanks · 3.7 mi
- Gateway FS, Inc.Underground Storage Tanks · 3.9 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Monroe County'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 Monroe County.
Total Sites
139
across Monroe County
Risk Level
Elevated
Highest-severity
1 Toxics Release Inventory facility
Sources Checked
across Monroe County
Severity Distribution
across Monroe County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Monroe County, two things run higher than the national average across Monroe County — PFAS (4 sites) and CAFO (3 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Check your specific parcel in Monroe County
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 Monroe County average
Your land is one point inside Monroe County
Everything above resolves to Monroe County as a whole — one PHZM band and one county frost record, read across 247K 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 county 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 county average.
Your Lot vs the Monroe County Average
Monroe County Average
- ●USDA Zones 7a, averaged across Monroe County
- ●One soil character for all of Monroe County
- ●Frost dates read at Monroe County's scale: Mar 24 to Nov 14
YOUR Parcel
- ✓Your exact zone, not Monroe County's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Monroe County
Pull a site-specific report for your exact address in Monroe County, Illinois — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Monroe County averages can't show:
We read public map data around Monroe County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Monroe County average
How we know this about Monroe County
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where Monroe County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Monroe County
When does frost risk typically end in Monroe County?
The last hard freeze (28°F) in Monroe County 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.
How long is the growing season in Monroe County?
Measured between 28°F hard freezes, Monroe County sees about 235 frost-free days — roughly Mar 24 through Nov 14, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 14 to Oct 31, about 200 days.
Is the soil safe to grow vegetables in Monroe County?
The federal record around Monroe County is a meaningful one — 139 documented sites, mostly Underground Storage Tanks entries (80), the nearest Brownfields record about 2.3 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.
Everything above is measured at Monroe County's scale — its 7a band and its 235-day season. Your yard writes its own version of Monroe County's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Illinois's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Monroe County’s own scale
9 of the readings below were taken at Monroe County's own scale — its own ~235-day span between 28°F freezes, the 3 most extensive soil series mapped here and 139 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Monroe County's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Monroe County's own 28°F hard-freeze dates and its ~235-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Monroe CountyUSDA NRCS SSURGO
- 139 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Brownfields record about 2.3 miles outFederal environmental registers
- Monroe County's boundary and the 246,592 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~235-day seasonGrowable Ground crop-matching engine
- Monroe County sitting wholly inside the Interior River Valleys and HillsUS EPA Level III Ecoregions
- Open occurrence records documented in Monroe County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Monroe County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Illinois grower plans around — written at state scale, so they stay on the state guidefrom Illinois
What this page can’t tell you
- How the season shifts across Monroe County — the ~235 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Monroe County's 246,592 acreswhy one lot differs from the next →
- Which of those 139 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over Monroe Countyread your own land →