Delta County, in Michigan, sits in USDA hardiness zone 5a — a zone band wide enough that plant choice, not possibility, is the interesting question.
Well-matched crops include cabbage, cranberry, lavender, and collard greens, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
Delta 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
Delta County holds more than one microclimate.
Soils and elevations shift across Delta 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 Delta County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Delta County — the short answer
Delta County, Michigan: USDA zone 5a, about 159 days between hard freezes, across 750K acres.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- May 8
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 14
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~159
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 750K 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 5a is Delta County's average, not your lot's — a low corner or a tree line moves it. Against Delta County's 159-day season, see what your own ground reads.
Heat in Delta County
Across a year, Delta County accumulates about 1,611 growing degree days above 50°F, about 489 fewer than the middle Michigan county — ahead of 12 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 Delta County
Across Delta County, the ground is predominantly Spodosols, where Kalkaska, Lupton, and Charlevoix are the most extensive named soil series. The soil is generally very poorly drained with a sand surface. Topsoil pH runs about 4.8–6.7, moderately acidic. Rainfall drains through hydrologic group A/D soils.
Soil order
Spodosols
Drainage
Very poorly drained
Prime farmland
5%
Hydric soils
45%
Soil still varies lot by lot — soil types explained.
How the ground varies across Delta County
The USDA soil survey maps 25% of Delta County as very poorly drained — but another 70% drains differently: 19% well drained, 17% poorly drained.
Kalkaska is the most extensive named soil at 9% of mapped acres, then Lupton (8%) and Charlevoix (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 Delta County
Each reading below is measured for Delta 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 Delta County are very poorly drained, in hydrologic group A/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 Delta County runs about pH 4.8–6.7, 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
Season length
MeasuredDelta County runs about 159 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
Winter hardiness
MeasuredDelta County sits in USDA hardiness zone 5a.
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 Delta County is in
Delta 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 Delta County
We scored all 1,086 plants against Delta County's own USDA zone 5a and its own 159-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 Delta 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 Apr 10; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near May 8 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 14 — long-season crops need about 90 days of runway, quick greens only 30. Even past midsummer there is room for a true fall garden here, and garlic planted near the close carries the momentum into next year.
Documented around Delta County
- monarch butterfly187 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Delta County
USGS estimates 5,303 lb of Glyphosate on Delta County farmland in 2019, its largest by weight, ahead of Metolachlor & Metolachlor-s (2,450 lb) and Metolachlor-s (1,983 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 Delta County — and how to grow with it.
We checked the federal record across Delta County — 406 documented sites across 6 of the 9 source types we track.
The most significant on record: 11 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 Delta 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 Delta County
Closest first, across Delta County. Listing isn't leaking, and distance isn't exposure.
- 39N 21W 28BAA 01Nitrate · 3.7 mi
- 39N 21W 23DD 01Nitrate · 4.0 mi
- 40N 21W 10DC 01Nitrate · 4.6 mi
- Lit-l-noc Cash MarketUnderground Storage Tanks · 4.8 mi
- 40N 22W 22DBA 01Nitrate · 5.6 mi
- K&M INDUSTRIAL LLCBrownfields · 5.8 mi
- CONSTRUCTION RESOURCES MANAGEMENT, INC. - GLADSTONE TANK FARMBrownfields · 5.9 mi
- Bay De Noc OilUnderground Storage Tanks · 6.0 mi
- Gladstone Municipal HarborUnderground Storage Tanks · 6.1 mi
- City of GladstoneUnderground Storage Tanks · 6.1 mi
- CITY OF GLADSTONEBrownfields · 6.1 mi
- State Police Post-gladstolneUnderground Storage Tanks · 6.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Delta 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 Delta County.
Total Sites
406
across Delta County
Risk Level
Elevated
Highest-severity
11 Superfund sites (none NPL-listed)
Sources Checked
across Delta County
Severity Distribution
across Delta County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Delta County, Superfund runs higher than the national average — 11 sites across Delta County. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check your specific parcel in Delta 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 Delta County average
Your land is one point inside Delta County
Everything above resolves to Delta County as a whole — one PHZM band and one county frost record, read across 750K 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 Delta County Average
Delta County Average
- ●USDA Zones 5a, averaged across Delta County
- ●One soil character for all of Delta County
- ●Frost dates read at Delta County's scale: May 8 to Oct 14
YOUR Parcel
- ✓Your exact zone, not Delta County's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Delta County
Pull a site-specific report for your exact address in Delta County, Michigan — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Delta County averages can't show:
We read public map data around Delta County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Delta County average
How we know this about Delta 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 Delta County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Delta County
When does frost risk typically end in Delta County?
The last hard freeze (28°F) in Delta County typically lands around May 8, 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 29.
How long is the growing season in Delta County?
Measured between 28°F hard freezes, Delta County sees about 159 frost-free days — roughly May 8 through Oct 14, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 29 to Sep 30, about 124 days.
Is the soil safe to grow vegetables in Delta County?
The federal record around Delta County is a meaningful one — 406 documented sites, mostly Underground Storage Tanks entries (188), the nearest Nitrate record about 3.7 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 Delta County's scale — its 5a band and its 159-day season. Your yard writes its own version of Delta 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 Delta County’s own scale
9 of the readings below were taken at Delta County's own scale — its own ~159-day span between 28°F freezes, the 3 most extensive soil series mapped here and 406 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Delta County's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Delta County's own 28°F hard-freeze dates and its ~159-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Delta CountyUSDA NRCS SSURGO
- 406 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Nitrate record about 3.7 miles outFederal environmental registers
- Delta County's boundary and the 749,500 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~159-day seasonGrowable Ground crop-matching engine
- Delta County sitting wholly inside the Northern Lakes and ForestsUS EPA Level III Ecoregions
- Open occurrence records documented in Delta County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Delta 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 Delta County — the ~159 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 Delta County's 749,500 acreswhy one lot differs from the next →
- Which of those 406 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 Delta Countyread your own land →