Monroe County, in Michigan, sits in USDA hardiness zone 6b — 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, lavender, and collard greens — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Monroe County lies within Metro Detroit & Southeast Michigan — a regional growing area with its own character.
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, Michigan: USDA zone 6b, about 207 days between hard freezes, across 352K acres.
- USDA zone
- 6b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 9
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Nov 2
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~207
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 352K 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 6b is Monroe County's average, not your lot's — a low corner or a tree line moves it. Against Monroe County's 207-day season, see what your own ground reads.
Heat in Monroe County
Across a year, Monroe County accumulates about 2,750 growing degree days above 50°F, about 650 more than the middle Michigan county — ahead of 80 of Michigan’s 83 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 Pewamo, Selfridge, and Lenawee are the most extensive named soil series. The soil is generally somewhat poorly drained with a loamy sand surface. Topsoil pH runs about 6.5–6.7, neutral. Rainfall drains through hydrologic group C/D soils.
Soil order
Alfisols
Drainage
Somewhat poorly drained
Prime farmland
7%
Hydric soils
50%
Soil still varies lot by lot — soil types explained.
How the ground varies across Monroe County
The USDA soil survey maps 42% of Monroe County as somewhat poorly drained — but another 53% drains differently: 35% poorly drained, 10% very poorly drained.
Pewamo is the most extensive named soil at 15% of mapped acres, then Selfridge (10%) and Lenawee (8%).
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 somewhat poorly drained, in hydrologic group C/D — ground that sheds water slowly.
Beds can stay saturated for days after heavy rain, and the roots of most vegetables, berries, and fruit trees suffocate or rot in soil that never drains.
Raised beds or mounded rows lift roots above the wet zone; choose water-tolerant crops for the lowest spots.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Monroe County runs about pH 6.5–6.7, 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
Season length
MeasuredMonroe County runs about 207 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
MeasuredMonroe County sits in USDA hardiness zone 6b.
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 Monroe County is in
Monroe County sits in the Huron/Erie Lake Plains — 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 6b and its own 207-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 Michigan 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 Mar 12; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 9 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 2 — 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
Spotted lanternfly documented 14 miles from Monroe County, first recorded 2023. What to watch for.
- monarch butterfly484 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Monroe County
USGS estimates 138,838 lb of Glyphosate on Monroe County farmland in 2019, its largest by weight, ahead of Metolachlor & Metolachlor-s (25,365 lb) and Atrazine (24,245 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 — 928 documented sites across 7 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 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.
- M.c. Eipperle, IncUnderground Storage Tanks · 0.6 mi
- MONROE COUNTY COMMUNITY COLLEGEBrownfields · 0.8 mi
- Monroe County Community CollegeUnderground Storage Tanks · 0.8 mi
- US ENVIRONMENTAL PROTECTION AGENCYBrownfields · 1.0 mi
- Monroe County Intermediate SchUnderground Storage Tanks · 1.1 mi
- GENOA HEALTHCARE LLCBrownfields · 1.2 mi
- Richard VeniaUnderground Storage Tanks · 1.3 mi
- Mabel Fanning TrustUnderground Storage Tanks · 1.4 mi
- Monroe County Fair AssocUnderground Storage Tanks · 1.7 mi
- Monroe County Library SystemUnderground Storage Tanks · 1.7 mi
- Monroe Public SchoolUnderground Storage Tanks · 2.5 mi
- Monroe Custer AirportUnderground Storage Tanks · 2.6 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.
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, PFAS runs higher than the national average — 8 sites across Monroe County. 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.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
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 352K 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 6b, averaged across Monroe County
- ●One soil character for all of Monroe County
- ●Frost dates read at Monroe County's scale: Apr 9 to Nov 2
YOUR Parcel
- ✓Your exact zone, not Monroe County's 6b
- ✓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, Michigan — 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 Apr 9, 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 30.
How long is the growing season in Monroe County?
Measured between 28°F hard freezes, Monroe County sees about 207 frost-free days — roughly Apr 9 through Nov 2, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 30 to Oct 19, about 172 days.
Is the soil safe to grow vegetables in Monroe County?
The federal record around Monroe County is a meaningful one — 928 documented sites, mostly Underground Storage Tanks entries (380), the nearest Underground Storage Tanks record about 0.6 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 6b band and its 207-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 Michigan'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 ~207-day span between 28°F freezes, the 3 most extensive soil series mapped here and 928 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 6bUSDA PHZM 2023
- Monroe County's own 28°F hard-freeze dates and its ~207-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
- 928 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 0.6 miles outFederal environmental registers
- Monroe County's boundary and the 351,589 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6b and a ~207-day seasonGrowable Ground crop-matching engine
- Monroe County sitting wholly inside the Huron/Erie Lake PlainsUS 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 Michigan grower plans around — written at state scale, so they stay on the state guidefrom Michigan
What this page can’t tell you
- How the season shifts across Monroe County — the ~207 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 351,589 acreswhy one lot differs from the next →
- Which of those 928 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 →