McHenry County, in Illinois, sits in USDA hardiness zone 5b — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Crops well matched to these conditions include cabbage, cranberry, lavender, 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
McHenry County holds more than one microclimate.
Soils and elevations shift across McHenry 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 McHenry County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
McHenry County — the short answer
McHenry County, Illinois: USDA zone 5b, about 190 days between hard freezes, across 386K acres.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 15
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 22
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~190
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 386K 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 5b is McHenry County's average, not your lot's — a low corner or a tree line moves it. Against McHenry County's 190-day season, see what your own ground reads.
Heat in McHenry County
Across a year, McHenry County accumulates about 2,576 growing degree days above 50°F, about 807 fewer than the middle Illinois county — ahead of 2 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 McHenry County
Across McHenry County, the ground is predominantly Mollisols, where Kidder, Kidami, and Pella are the most extensive named soil series. The soil is generally well drained with a silt loam surface. Topsoil pH runs about 6.4–7.0, neutral. Rainfall drains through hydrologic group B soils.
Soil order
Mollisols
Drainage
Well drained
Prime farmland
57%
Hydric soils
26%
Soil still varies lot by lot — soil types explained.
How the ground varies across McHenry County
The USDA soil survey maps 42% of McHenry County as well drained — but another 55% drains differently: 20% poorly drained, 13% somewhat poorly drained.
Kidder is the most extensive named soil at 7% of mapped acres, then Kidami (6%) and Pella (6%).
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 McHenry County
Each reading below is measured for McHenry 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 McHenry 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 McHenry County runs about pH 6.4–7.0, 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 26% of McHenry 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
MeasuredMcHenry County runs about 190 days between hard freezes — a moderate growing season.
There is room for the full run of cool-season crops plus a warm-season main crop, but the calendar is tight enough that a late spring or early fall frost still decides how much finishes.
Time warm-season transplants to your last hard freeze, and a few weeks of season extension turns a near-miss harvest into a sure one.
NOAA 1991–2020 Climate Normals
The kind of country McHenry County is in
McHenry County spans 2 EPA Level III ecoregions — Southeastern Wisconsin Till Plains (51%) and Central Corn Belt Plains (49%). Which one your land falls in changes what grows wild there and how the ground behaves, and a county-wide answer cannot tell you which.
What Grows in McHenry County
We scored all 1,086 plants against McHenry County's own USDA zone 5b and its own 190-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 McHenry County?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Mar 18; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 15 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 22 — long-season crops need about 90 days of runway, quick greens only 30. Even past midsummer there is room for a true fall garden here, and garlic planted near the close carries the momentum into next year.
Documented around McHenry County
Spotted lanternfly documented 30 miles from McHenry County, first recorded 2023. What to watch for.
- Japanese beetle7 documented records
- monarch butterfly631 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in McHenry County
USGS estimates 178,503 lb of Glyphosate on McHenry County farmland in 2019, its largest by weight, ahead of Acetochlor (93,864 lb) and Atrazine (89,729 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 McHenry County — and how to grow with it.
We checked the federal record across McHenry County — 1,237 documented sites across 8 of the 9 source types we track.
The most significant on record: 11 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
There's a meaningful federal record across McHenry 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 McHenry County
Closest first, across McHenry County. Listing isn't leaking, and distance isn't exposure.
- WOODSTOCK, ILPFAS · 900 ft
- WOODSTOCK CITY OFBrownfields · 2000 ft
- Peter Baker & Sons Co.Underground Storage Tanks · 2000 ft
- City of WoodstockUnderground Storage Tanks · 2100 ft
- WOODSTOCK DIE CAST INCToxics Release Inventory · 2100 ft
- WOODSTOCK DIE CAST INCBrownfields · 2100 ft
- WOODSTOCK DIE CAST INCSuperfund · 2100 ft
- MobilUnderground Storage Tanks · 2400 ft
- Law OfficeUnderground Storage Tanks · 2400 ft
- Woodstock MobilUnderground Storage Tanks · 0.5 mi
- Gavers Asphalt Paving & ExcavatingUnderground Storage Tanks · 0.5 mi
- NOODLES RESTAURANTBrownfields · 0.5 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from McHenry 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 McHenry County.
Severity Distribution
across McHenry County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around McHenry County, two things run higher than the national average across McHenry County — PFAS (14 sites) and Toxics Release Inventory (97 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.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Check your specific parcel in McHenry 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 McHenry County average
Your land is one point inside McHenry County
Everything above resolves to McHenry County as a whole — one PHZM band and one county frost record, read across 386K 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 McHenry County Average
McHenry County Average
- ●USDA Zones 5b, averaged across McHenry County
- ●One soil character for all of McHenry County
- ●Frost dates read at McHenry County's scale: Apr 15 to Oct 22
YOUR Parcel
- ✓Your exact zone, not McHenry County's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in McHenry County
Pull a site-specific report for your exact address in McHenry County, Illinois — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that McHenry County averages can't show:
We read public map data around McHenry County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the McHenry County average
How we know this about McHenry 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 McHenry County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about McHenry County
When does frost risk typically end in McHenry County?
The last hard freeze (28°F) in McHenry County typically lands around Apr 15, 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 May 6.
How long is the growing season in McHenry County?
Measured between 28°F hard freezes, McHenry County sees about 190 frost-free days — roughly Apr 15 through Oct 22, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 6 to Oct 8, about 155 days.
Is the soil safe to grow vegetables in McHenry County?
The federal record around McHenry County is a meaningful one — 1,237 documented sites, mostly Underground Storage Tanks entries (536), the nearest PFAS 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.
Everything above is measured at McHenry County's scale — its 5b band and its 190-day season. Your yard writes its own version of McHenry 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 McHenry County’s own scale
9 of the readings below were taken at McHenry County's own scale — its own ~190-day span between 28°F freezes, the 3 most extensive soil series mapped here and 1,237 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- McHenry County's own USDA hardiness band, zones 5bUSDA PHZM 2023
- McHenry County's own 28°F hard-freeze dates and its ~190-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in McHenry CountyUSDA NRCS SSURGO
- 1,237 documented contamination sites inside the county boundary, distance-sorted from its center — the closest PFAS record about 0.2 miles outFederal environmental registers
- McHenry County's boundary and the 386,177 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~190-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions McHenry County spans, Southeastern Wisconsin Till Plains the largestUS EPA Level III Ecoregions
- Open occurrence records documented in McHenry County for 2 tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto McHenry 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 McHenry County — the ~190 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 McHenry County's 386,177 acreswhy one lot differs from the next →
- Which of those 1,237 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 McHenry Countyread your own land →