Keweenaw County, in Michigan, sits in USDA hardiness zone 5b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
The conditions favor cabbage, cranberry, lavender, and collard greens, among others — though every individual site edits that list with its own soil, sun, and drainage.
Keweenaw County lies within the Upper Peninsula — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Keweenaw County holds more than one microclimate.
Soils and elevations shift across Keweenaw 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 Keweenaw County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Keweenaw County — the short answer
Keweenaw County, Michigan: USDA zone 5b, about 176 days between hard freezes, across 346K acres.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 30
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 23
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~176
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 346K 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 Keweenaw County's average, not your lot's — a low corner or a tree line moves it. Against Keweenaw County's 176-day season, see what your own ground reads.
Heat in Keweenaw County
Across a year, Keweenaw County accumulates about 1,441 growing degree days above 50°F, about 659 fewer than the middle Michigan county — ahead of 1 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 Keweenaw County
Across Keweenaw County, the ground is predominantly Spodosols, where Montreal, Arcadian, and Michigamme are the most extensive named soil series. The soil is generally well drained with a fine sandy loam surface. Topsoil pH runs about 4.7–5.3, very strongly acidic. Rainfall drains through hydrologic group D soils.
Soil order
Spodosols
Drainage
Well drained
Hydric soils
24%
Soil still varies lot by lot — soil types explained.
How the ground varies across Keweenaw County
The USDA soil survey maps 17% of Keweenaw County as well drained — but another 29% drains differently: 14% moderately well drained, 7% very poorly drained.
Montreal is the most extensive named soil at 11% of mapped acres, then Arcadian (9%) and Michigamme (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 Keweenaw County
Each reading below is measured for Keweenaw 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 Keweenaw County are well drained, in hydrologic group D — 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 Keweenaw County runs about pH 4.7–5.3, on the acidic side.
Blueberries, potatoes, and rhododendrons thrive in it, but most vegetables start locking out nutrients below about pH 6.0 and grow pale and stunted no matter how much you feed them.
A measured lime application raises pH for the crops that need it — but test first, because the right rate depends on your own soil, not the county average.
USDA NRCS SSURGO
Wet ground
MeasuredAbout 24% of Keweenaw 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
MeasuredKeweenaw County runs about 176 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 Keweenaw County is in
Keweenaw County sits in the Northern Lakes and Forests — EPA Level III, inside the wider Northern Forests. One consistent ecological setting across the whole county.
What Grows in Keweenaw County
We scored all 1,086 plants against Keweenaw County's own USDA zone 5b and its own 176-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 Keweenaw County?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Apr 2; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 30 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 23 — long-season crops need about 90 days of runway, quick greens only 30. The tail of the season still works: sixty-day crops into late summer, quick greens after, garlic last of all.
Documented around Keweenaw County
- monarch butterfly27 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Keweenaw County
USGS estimates 6 lb of Carbaryl on Keweenaw County farmland in 2019, its largest by weight, ahead of 2,4-d (3 lb) and Glyphosate (2 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 Keweenaw County — and how to grow with it.
We checked the federal record across Keweenaw County — 195 documented sites across 6 of the 9 source types we track.
The most significant on record: 5 Superfund sites (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 Keweenaw 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 Keweenaw County
Closest first, across Keweenaw County. Listing isn't leaking, and distance isn't exposure.
- SenecaMining · 1.0 mi
- Seneca No. 2 MineMining · 1.0 mi
- Unnamed Copper ProspectMining · 1.0 mi
- Fissure MinesMining · 1.3 mi
- Manhattan ExplorationMining · 1.4 mi
- North American MineMining · 1.6 mi
- North CliffMining · 1.8 mi
- CliffMining · 1.8 mi
- Cliff FissureMining · 1.8 mi
- Cliff Copper MineMining · 1.8 mi
- Cliff Mining Co.Mining · 2.5 mi
- OjibwayMining · 2.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Keweenaw 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 Keweenaw County.
Total Sites
195
across Keweenaw County
Risk Level
Elevated
Highest-severity
5 Superfund sites (none NPL-listed)
Sources Checked
across Keweenaw County
Severity Distribution
across Keweenaw County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Keweenaw County, two things run higher than the national average across Keweenaw County — Mining (154 sites) and Superfund (5 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check your specific parcel in Keweenaw 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 Keweenaw County average
Your land is one point inside Keweenaw County
Everything above resolves to Keweenaw County as a whole — one PHZM band and one county frost record, read across 346K 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 Keweenaw County Average
Keweenaw County Average
- ●USDA Zones 5b, averaged across Keweenaw County
- ●One soil character for all of Keweenaw County
- ●Frost dates read at Keweenaw County's scale: Apr 30 to Oct 23
YOUR Parcel
- ✓Your exact zone, not Keweenaw County's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Keweenaw County
Pull a site-specific report for your exact address in Keweenaw County, Michigan — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Keweenaw County averages can't show:
We read public map data around Keweenaw County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Keweenaw County average
How we know this about Keweenaw 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 Keweenaw County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Keweenaw County
When does frost risk typically end in Keweenaw County?
The last hard freeze (28°F) in Keweenaw County typically lands around Apr 30, 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 21.
How long is the growing season in Keweenaw County?
Measured between 28°F hard freezes, Keweenaw County sees about 176 frost-free days — roughly Apr 30 through Oct 23, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 21 to Oct 9, about 141 days.
Is the soil safe to grow vegetables in Keweenaw County?
The federal record around Keweenaw County is a meaningful one — 195 documented sites, mostly Mining entries (154), the nearest Mining record about 1.0 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 Keweenaw County's scale — its 5b band and its 176-day season. Your yard writes its own version of Keweenaw 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 Keweenaw County’s own scale
9 of the readings below were taken at Keweenaw County's own scale — its own ~176-day span between 28°F freezes, the 3 most extensive soil series mapped here and 195 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Keweenaw County's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Keweenaw County's own 28°F hard-freeze dates and its ~176-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Keweenaw CountyUSDA NRCS SSURGO
- 195 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Mining record about 1.0 miles outFederal environmental registers
- Keweenaw County's boundary and the 345,671 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~176-day seasonGrowable Ground crop-matching engine
- Keweenaw County sitting wholly inside the Northern Lakes and ForestsUS EPA Level III Ecoregions
- Open occurrence records documented in Keweenaw County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Keweenaw 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 Keweenaw County — the ~176 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 Keweenaw County's 345,671 acreswhy one lot differs from the next →
- Which of those 195 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 Keweenaw Countyread your own land →