Marshall County, in Illinois, sits in USDA hardiness zone 5b — a zone band wide enough that plant choice, not possibility, is the interesting question.
Expect cabbage, cranberry, 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
Marshall County holds more than one microclimate.
Soils and elevations shift across Marshall 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 Marshall County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Marshall County — the short answer
Marshall County, Illinois: USDA zone 5b, about 203 days between hard freezes, across 248K acres.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 10
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 30
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~203
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 248K 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 Marshall County's average, not your lot's — a low corner or a tree line moves it. Against Marshall County's 203-day season, see what your own ground reads.
Heat in Marshall County
Across a year, Marshall County accumulates about 3,031 growing degree days above 50°F, about 352 fewer than the middle Illinois county — ahead of 21 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 Marshall County
Across Marshall County, the ground is predominantly Mollisols, where Harco, Sable, and Rutland are the most extensive named soil series. The soil is generally well drained with a silt loam surface. Topsoil pH runs about 6.2–6.8, slightly acidic. Rainfall drains through hydrologic group C soils.
Soil order
Mollisols
Drainage
Well drained
Prime farmland
59%
Hydric soils
16%
Soil still varies lot by lot — soil types explained.
How the ground varies across Marshall County
The USDA soil survey maps 31% of Marshall County as well drained — but another 66% drains differently: 28% somewhat poorly drained, 22% moderately well drained.
Harco is the most extensive named soil at 7% of mapped acres, then Sable (6%) and Rutland (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 Marshall County
Each reading below is measured for Marshall 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 Marshall County are well drained, in hydrologic group C — 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 Marshall County runs about pH 6.2–6.8, 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 16% of Marshall 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
MeasuredMarshall County runs about 203 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 Marshall County is in
Marshall County spans 2 EPA Level III ecoregions — Central Corn Belt Plains (67%) and Interior River Valleys and Hills (33%). 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 Marshall County
We scored all 1,086 plants against Marshall County's own USDA zone 5b and its own 203-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 Marshall County?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Mar 13; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 10 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 30 — 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.
Documented around Marshall County
- monarch butterfly1 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Marshall County
USGS estimates 208,052 lb of Glyphosate on Marshall County farmland in 2019, its largest by weight, ahead of Atrazine (98,114 lb) and Metolachlor & Metolachlor-s (88,534 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 Marshall County — and how to grow with it.
We checked the federal record across Marshall County — 127 documented sites across 6 of the 9 source types we track.
The most significant on record: 1 Superfund site (none NPL-listed). 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 Marshall 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 Marshall County
Closest first, across Marshall County. Listing isn't leaking, and distance isn't exposure.
- RUPIPER EQUIPMENT COBrownfields · 1.4 mi
- Marshall County AirportUnderground Storage Tanks · 1.4 mi
- OBRIEN STEEL META TECH DIVBrownfields · 2.8 mi
- Lacon Minit Mart #631Underground Storage Tanks · 2.8 mi
- Stickel Ray LUnderground Storage Tanks · 2.9 mi
- MIDWEST MATERIAL COBrownfields · 3.0 mi
- FERRELL BODY SHOPBrownfields · 3.4 mi
- Jerome GreenUnderground Storage Tanks · 3.4 mi
- Marshall County Sheriff DeptUnderground Storage Tanks · 3.4 mi
- NORCO FUELS 6Brownfields · 3.5 mi
- Casey's General StoreUnderground Storage Tanks · 3.5 mi
- St Josephs Nursing Home IncUnderground Storage Tanks · 3.5 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Marshall 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 Marshall County.
Total Sites
127
across Marshall County
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
across Marshall County
Severity Distribution
across Marshall County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Marshall County, two things run higher than the national average across Marshall County — CAFO (3 sites) and Underground Storage Tanks (86 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Marshall 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 Marshall County average
Your land is one point inside Marshall County
Everything above resolves to Marshall County as a whole — one PHZM band and one county frost record, read across 248K 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 Marshall County Average
Marshall County Average
- ●USDA Zones 5b, averaged across Marshall County
- ●One soil character for all of Marshall County
- ●Frost dates read at Marshall County's scale: Apr 10 to Oct 30
YOUR Parcel
- ✓Your exact zone, not Marshall County's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Marshall County
Pull a site-specific report for your exact address in Marshall County, Illinois — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Marshall County averages can't show:
We read public map data around Marshall County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Marshall County average
How we know this about Marshall 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 Marshall County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Marshall County
When does frost risk typically end in Marshall County?
The last hard freeze (28°F) in Marshall County typically lands around Apr 10, 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 1.
How long is the growing season in Marshall County?
Measured between 28°F hard freezes, Marshall County sees about 203 frost-free days — roughly Apr 10 through Oct 30, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 1 to Oct 16, about 168 days.
Is the soil safe to grow vegetables in Marshall County?
The federal record around Marshall County is a meaningful one — 127 documented sites, mostly Underground Storage Tanks entries (86), the nearest Brownfields record about 1.4 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 Marshall County's scale — its 5b band and its 203-day season. Your yard writes its own version of Marshall 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 Marshall County’s own scale
9 of the readings below were taken at Marshall County's own scale — its own ~203-day span between 28°F freezes, the 3 most extensive soil series mapped here and 127 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Marshall County's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Marshall County's own 28°F hard-freeze dates and its ~203-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Marshall CountyUSDA NRCS SSURGO
- 127 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Brownfields record about 1.4 miles outFederal environmental registers
- Marshall County's boundary and the 247,566 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~203-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Marshall County spans, Central Corn Belt Plains the largestUS EPA Level III Ecoregions
- Open occurrence records documented in Marshall County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Marshall 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 Marshall County — the ~203 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 Marshall County's 247,566 acreswhy one lot differs from the next →
- Which of those 127 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 Marshall Countyread your own land →