Henderson 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.
Expect cabbage, blueberry, lavender, and collard greens to be strong candidates here; the deciding factors on any one parcel stay local — soil, sun, and drainage.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Henderson County holds more than one microclimate.
Soils and elevations shift across Henderson 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 Henderson County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Henderson County — the short answer
Henderson County, Illinois: USDA zone 5b, about 211 days between hard freezes, across 242K acres.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 4
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Nov 1
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~211
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 242K 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 Henderson County's average, not your lot's — a low corner or a tree line moves it. Against Henderson County's 211-day season, see what your own ground reads.
Heat in Henderson County
Across a year, Henderson County accumulates about 3,239 growing degree days above 50°F, about 144 fewer than the middle Illinois county — ahead of 40 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 Henderson County
Across Henderson County, the ground is predominantly Mollisols, where Muscatune, Seaton, and Coloma 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
Mollisols
Drainage
Well drained
Prime farmland
40%
Hydric soils
18%
Soil still varies lot by lot — soil types explained.
How the ground varies across Henderson County
The USDA soil survey maps 45% of Henderson County as well drained — but another 50% drains differently: 20% somewhat poorly drained, 18% poorly drained.
Muscatune is the most extensive named soil at 15% of mapped acres, then Seaton (14%) and Coloma (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 Henderson County
Each reading below is measured for Henderson 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 Henderson 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 Henderson 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 18% of Henderson 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
MeasuredHenderson County runs about 211 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 Henderson County is in
Henderson 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 Henderson County
We scored all 1,086 plants against Henderson County's own USDA zone 5b and its own 211-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 Henderson County?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 7; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 4 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 1 — 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 Henderson County
- Japanese beetle2 documented records
- monarch butterfly341 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Henderson County
USGS estimates 149,525 lb of Glyphosate on Henderson County farmland in 2019, its largest by weight, ahead of Atrazine (68,230 lb) and Acetochlor (60,271 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 Henderson County — and how to grow with it.
We checked the federal record across Henderson County — 53 documented sites across 5 of the 9 source types we track.
The most significant on record: 2 concentrated animal feeding operations. Large-scale animal operations that can contaminate soil and groundwater with nitrates and pathogens.
The federal record across Henderson County is a modest one — a typical footprint for a growing area. Nothing here calls for alarm; it's worth knowing which recorded sites sit closest to where you grow, and each one on the map carries its type and location. If one turns out to be a near neighbor, a one-time soil test settles the question.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Henderson County
Closest first, across Henderson County. Listing isn't leaking, and distance isn't exposure.
- Wanda Holford FillmanUnderground Storage Tanks · 3.5 mi
- Gladstone Township OfUnderground Storage Tanks · 3.5 mi
- Lock & Dam 18Underground Storage Tanks · 3.6 mi
- Former Gladstone Grain Co.Underground Storage Tanks · 3.7 mi
- Union School Dist 115Underground Storage Tanks · 3.7 mi
- Gibbs ConvenienceUnderground Storage Tanks · 4.8 mi
- Tri-County Agro IncUnderground Storage Tanks · 4.8 mi
- County Highway DeptUnderground Storage Tanks · 4.9 mi
- IDOTBrownfields · 4.9 mi
- Crop Production SerUnderground Storage Tanks · 5.0 mi
- STRONGHURST AUTOBODYBrownfields · 5.0 mi
- Stronghurst Fast StopUnderground Storage Tanks · 5.0 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Henderson 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 Henderson County.
Total Sites
53
across Henderson County
Risk Level
Moderate
Highest-severity
2 concentrated animal feeding operations
Sources Checked
across Henderson County
Severity Distribution
across Henderson County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Henderson County, Underground Storage Tanks runs higher than the national average — 38 sites across Henderson County. That's not a problem with your land — it's information about it.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Henderson 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 Henderson County average
Your land is one point inside Henderson County
Everything above resolves to Henderson County as a whole — one PHZM band and one county frost record, read across 242K 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 Henderson County Average
Henderson County Average
- ●USDA Zones 5b, averaged across Henderson County
- ●One soil character for all of Henderson County
- ●Frost dates read at Henderson County's scale: Apr 4 to Nov 1
YOUR Parcel
- ✓Your exact zone, not Henderson County's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Henderson County
Pull a site-specific report for your exact address in Henderson County, Illinois — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Henderson County averages can't show:
We read public map data around Henderson County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Henderson County average
How we know this about Henderson 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 Henderson County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Henderson County
When does frost risk typically end in Henderson County?
The last hard freeze (28°F) in Henderson County typically lands around Apr 4, 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 25.
How long is the growing season in Henderson County?
Measured between 28°F hard freezes, Henderson County sees about 211 frost-free days — roughly Apr 4 through Nov 1, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 25 to Oct 18, about 176 days.
Is the soil safe to grow vegetables in Henderson County?
The federal record around Henderson County shows 53 documented sites, mostly Underground Storage Tanks entries (38), the nearest Underground Storage Tanks record about 3.5 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.
Everything above is measured at Henderson County's scale — its 5b band and its 211-day season. Your yard writes its own version of Henderson 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 Henderson County’s own scale
9 of the readings below were taken at Henderson County's own scale — its own ~211-day span between 28°F freezes, the 3 most extensive soil series mapped here and 53 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Henderson County's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Henderson County's own 28°F hard-freeze dates and its ~211-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Henderson CountyUSDA NRCS SSURGO
- 53 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 3.5 miles outFederal environmental registers
- Henderson County's boundary and the 242,427 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~211-day seasonGrowable Ground crop-matching engine
- Henderson County sitting wholly inside the Interior River Valleys and HillsUS EPA Level III Ecoregions
- Open occurrence records documented in Henderson County for 2 tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Henderson 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 Henderson County — the ~211 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 Henderson County's 242,427 acreswhy one lot differs from the next →
- Which of those 53 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 Henderson Countyread your own land →