Sanilac County, in Michigan, sits in USDA hardiness zone 6a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
The conditions favor cabbage, hazelnut, lavender, and collard greens, among others — though every individual site edits that list with its own soil, sun, and drainage.
Sanilac County lies within the Michigan Thumb — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Sanilac County holds more than one microclimate.
Soils and elevations shift across Sanilac 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 Sanilac County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Sanilac County — the short answer
Sanilac County, Michigan: USDA zone 6a, about 200 days between hard freezes, across 616K acres.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 19
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Nov 5
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~200
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 616K 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 6a is Sanilac County's average, not your lot's — a low corner or a tree line moves it. Against Sanilac County's 200-day season, see what your own ground reads.
Heat in Sanilac County
Across a year, Sanilac County accumulates about 2,166 growing degree days above 50°F, about 66 more than the middle Michigan county — ahead of 46 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 Sanilac County
Across Sanilac County, the ground is predominantly Alfisols, where Parkhill, Guelph, and Conover are the most extensive named soil series. The soil is generally poorly drained with a loam surface. Topsoil pH runs about 6.5–7.3, neutral. Rainfall drains through hydrologic group C/D soils.
Soil order
Alfisols
Drainage
Poorly drained
Prime farmland
13%
Hydric soils
49%
Soil still varies lot by lot — soil types explained.
How the ground varies across Sanilac County
The USDA soil survey maps 38% of Sanilac County as poorly drained — but another 62% drains differently: 29% somewhat poorly drained, 22% well drained.
Parkhill is the most extensive named soil at 33% of mapped acres, then Guelph (11%) and Conover (11%).
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 Sanilac County
Each reading below is measured for Sanilac 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 Sanilac County are 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 Sanilac County runs about pH 6.5–7.3, 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
MeasuredSanilac County runs about 200 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
MeasuredSanilac County sits in USDA hardiness zone 6a.
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 Sanilac County is in
Sanilac 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 Sanilac County
We scored all 1,086 plants against Sanilac County's own USDA zone 6a and its own 200-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 Sanilac 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 22; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 19 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 5 — long-season crops need about 90 days of runway, quick greens only 30. There is slack in a calendar like this — late plantings, second rounds of favorites, and a fall bench that keeps beds working.
Documented around Sanilac County
Survey cells within 31 miles of Sanilac County checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 66 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 Sanilac County
USGS estimates 298,389 lb of Glyphosate on Sanilac County farmland in 2019, its largest by weight, ahead of Metolachlor & Metolachlor-s (68,318 lb) and Metolachlor-s (61,210 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 Sanilac County — and how to grow with it.
We checked the federal record across Sanilac County — 350 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 Sanilac 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 Sanilac County
Closest first, across Sanilac County. Listing isn't leaking, and distance isn't exposure.
- CARSONVILLE-PT SANILAC SCHOOLSBrownfields · 1.5 mi
- Carsonville-port Sanilac SchoolsUnderground Storage Tanks · 2.0 mi
- MI DEPT/TRANSPORTATION B01-74062Brownfields · 2.1 mi
- Carsonville TireUnderground Storage Tanks · 2.1 mi
- Backus Oil Self-serveUnderground Storage Tanks · 2.1 mi
- WILSON SITESuperfund · 2.1 mi
- Village Of CarsonvilleUnderground Storage Tanks · 2.2 mi
- Backus Oil CoUnderground Storage Tanks · 2.3 mi
- Asher Oil & Gas Co IncUnderground Storage Tanks · 2.4 mi
- Sanilac Ct Rd Comm Garage #6Underground Storage Tanks · 2.4 mi
- Salmon Enterprises IncUnderground Storage Tanks · 2.6 mi
- TOTAL PETROLEUM (NORTH AMERICA) LTDBrownfields · 2.9 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Sanilac 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 Sanilac County.
Total Sites
350
across Sanilac County
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
across Sanilac County
Severity Distribution
across Sanilac County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Sanilac County, PFAS runs higher than the national average — 4 sites across Sanilac County. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
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 Sanilac 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 Sanilac County average
Your land is one point inside Sanilac County
Everything above resolves to Sanilac County as a whole — one PHZM band and one county frost record, read across 616K 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 Sanilac County Average
Sanilac County Average
- ●USDA Zones 6a, averaged across Sanilac County
- ●One soil character for all of Sanilac County
- ●Frost dates read at Sanilac County's scale: Apr 19 to Nov 5
YOUR Parcel
- ✓Your exact zone, not Sanilac County's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Sanilac County
Pull a site-specific report for your exact address in Sanilac County, Michigan — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Sanilac County averages can't show:
We read public map data around Sanilac County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Sanilac County average
How we know this about Sanilac 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 Sanilac County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Sanilac County
When does frost risk typically end in Sanilac County?
The last hard freeze (28°F) in Sanilac County typically lands around Apr 19, 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 10.
How long is the growing season in Sanilac County?
Measured between 28°F hard freezes, Sanilac County sees about 200 frost-free days — roughly Apr 19 through Nov 5, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 10 to Oct 22, about 165 days.
Is the soil safe to grow vegetables in Sanilac County?
The federal record around Sanilac County is a meaningful one — 350 documented sites, mostly Underground Storage Tanks entries (214), the nearest Brownfields record about 1.5 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 Sanilac County's scale — its 6a band and its 200-day season. Your yard writes its own version of Sanilac 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 Sanilac County’s own scale
9 of the readings below were taken at Sanilac County's own scale — its own ~200-day span between 28°F freezes, the 3 most extensive soil series mapped here and 350 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Sanilac County's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Sanilac County's own 28°F hard-freeze dates and its ~200-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Sanilac CountyUSDA NRCS SSURGO
- 350 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Brownfields record about 1.5 miles outFederal environmental registers
- Sanilac County's boundary and the 616,045 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~200-day seasonGrowable Ground crop-matching engine
- Sanilac County sitting wholly inside the Huron/Erie Lake PlainsUS EPA Level III Ecoregions
- Open occurrence records documented in Sanilac County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Sanilac 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 Sanilac County — the ~200 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 Sanilac County's 616,045 acreswhy one lot differs from the next →
- Which of those 350 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 Sanilac Countyread your own land →