The Driftless Area spans USDA hardiness zones 4b-5a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
An unglaciated landscape of steep ridges, deep valleys, and spring-fed coulees in the Upper Midwest — a stronghold of diversified small farms and cold-hardy fruit. Well-matched crops include sweet corn, tomato, cranberry, and potato, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
The Driftless Area spans Illinois, Iowa, Minnesota and Wisconsin. Its footprint follows the EPA Level III ecoregion boundary; the counties linked below are representative of the region, not an exhaustive list.
Your yard isn't all of the Driftless Area.
The Driftless Area spans USDA zones 4b-5a, but your parcel sits in exactly one — and slope, tree cover, and low spots nudge it further. 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 Driftless Area — soil, climate, flood, and parcel records. How we handle your address.
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The Driftless Area — the short answer
The Driftless Area: USDA zones 4b-5a, 165–189 frost-free days, across 4 states.
- USDA zones
- 4b-5a
- USDA PHZM 2023, aggregated over the footprint
- Frost-free season
- 165–189 days
- NOAA Regional Climate Centers ACIS, 1991-2020
- Counties
- 26
- US Census TIGER/Line 2025
- Region type
- EPA ecoregion
- Growable Ground growing-region registry
Region boundary: Growable Ground growing-region registry — curated county clusters, EPA Level III ecoregions, and town clusters drawn finer than any county. Where a region publishes no measured season, no season figure is shown.
Hardiness Zone Range
What Grows in the Driftless Area
Plants matched to the Driftless Area's USDA zones 4b-5a, ordered by how much hardiness margin each has across the region — the ones with room to spare at both ends of this band lead. Each links to its full growing profile.
Native Plants of the Driftless Area
Plants the USDA PLANTS Database documents as native and present in all 4 states this region crosses, kept only where the published hardiness range meets the Driftless Area’s USDA zones 4b-5a — closest range match first. Presence is recorded by state, so a plant can be documented across the state and still be scarce in your corner of the region.
The ground across the Driftless Area
The USDA soil survey maps this ground county by county. These are those records weighted by land area across 26 member counties — this region’s own profile, not a state figure.
The ground is predominantly Alfisols, at 63% of mapped acres, followed by Mollisols (19%), Entisols (13%) and Inceptisols (3%). Seven soil orders appear somewhere inside the footprint, which is the honest reason a regional soil answer only goes so far. The most extensive named soils are Fayette, Downs, and Seaton.
70% of those acres are well drained, and another 10% moderately well drained, 6% somewhat poorly drained. Topsoil pH runs 5.5–6.7 between the lowest and the highest county on record. 22% of the footprint is classed prime farmland.
Soil order
Alfisols
Drainage
Well drained
Topsoil pH
5.5–6.7
Hydric soils
6%
Soil changes across a driveway, so which of these your own ground sits on is a parcel question rather than a regional one. Eau Claire County holds the most wetland ground here, at 13% — soil types explained.
USDA NRCS SSURGO via Soil Data Access
What this means for growing in the Driftless Area
The soil survey reads this ground county by county, and the readings above are those records summed across the Driftless Area. Here is what they mean for a garden here — and the move an experienced grower makes about each one.
Drainage
From county records70% of the mapped acres across the Driftless Area are well drained — ground that drains quickly. That is area-weighted across all 26 of its mapped counties.
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
From county recordsTopsoil across the Driftless Area runs pH 5.5–6.7 — near neutral in 24 of its 26 counties.
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
Safe to Grow Here?
What the federal record shows across the Driftless Area — and how to grow with it.
Across the Driftless Area's 26 counties the federal record holds 13,237 documented sites, mostly Underground Storage Tanks (6,243), Brownfields (2,997) and Nitrate (2,122). The heaviest single county is Olmsted County, with 1,085.
That is a regional count, not a reading of any one lot — proximity to a documented site is information, not a diagnosis. Open the map outlined to the Driftless Area to see which records sit where you actually grow.
Sources Checked
Summed across the 26 counties in the Driftless Area
A note from Gnorman
What an experienced grower watches for around here
In and around the Driftless Area, two things run higher than the national average across the 26 counties in the Driftless Area — Mining (1,268 sites) and CAFO (134 sites). That's not a problem with your land — it's information about 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.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Your land is one point inside the Driftless Area
Everything above resolves to the Driftless Area as a whole — a footprint spanning USDA zones 4b-5a. Your parcel sits in exactly one of them. 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 region 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 regional average.
Your Lot vs the Driftless Area Average
Driftless Area Average
- ●USDA Zones 4b-5a, averaged across Driftless Area
- ●One soil character for all of Driftless Area
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not Driftless Area's 4b-5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in the Driftless Area
Pull a site-specific report for your exact address in the Driftless Area — soil, sun, drainage, frost risk, contamination, and scored plant recommendations.
Three things about your lot that Driftless Area averages can't show:
We read public map data around The Driftless Area — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Driftless Area average
How we know this about the Driftless Area
The boundary: an EPA Level III ecoregion (an area sharing climate, soils, and vegetation). Growing regions have no official boundary, so this footprint is our published one, and every figure on this page was measured over the counties inside it rather than borrowed from the state around it.
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, aggregated across the footprint; the growing season from NOAA Regional Climate Centers ACIS 1991–2020 28°F normals, read at each member’s own record; boundaries from US Census TIGER/Line 2025; the contamination record from the federal sources named in that beat above; the soil from the USDA NRCS SSURGO survey, read at each member county’s own record and weighted to this footprint by land area. Where a member carries no record of its own, it is absent from the figure rather than filled in.
Common questions about the Driftless Area
What hardiness zone is the Driftless Area?
The Driftless Area spans USDA hardiness zones 4b-5a, aggregated from the USDA Agricultural Research Service Plant Hardiness Zone Map 2023 across the region's counties. Zones reflect average annual extreme minimum temperatures from 1991–2020 data.
How long is the growing season in the Driftless Area?
Measured between 28°F hard freezes, the Driftless Area's counties mostly run 173 to 185 frost-free days, median 180 (NOAA Regional Climate Centers ACIS, 1991–2020, over 26 member counties). That 12-day spread is the honest read — no single season describes 26 counties, and each county guide below carries its own.
When does frost risk end in the Driftless Area?
Across the Driftless Area, the middle half of member counties see their last 28°F hard freeze between Apr 16 and Apr 25 (median Apr 22), and their first fall freeze between Oct 15 and Oct 19. Those are hard freezes, not the last light frost: tender transplants wait for about May 13, and elevation decides which end of a 9-day spread you garden in.
What grows well in the Driftless Area?
The Driftless Area's conditions suit plants such as Sweet Corn, Tomato, Cranberry, Potato, Pumpkin, Apple. What actually thrives on any one site still turns on its specific soil, sun, and drainage — we score each plant against the real conditions at your address.
How is the Driftless Area defined?
The Driftless Area's footprint follows an EPA Level III ecoregion — a boundary drawn where climate, soils, and vegetation actually change rather than where a state line falls. It covers 26 counties, and the counties linked on this page are representative of the region, not an exhaustive list.
Which states does the Driftless Area cover?
The Driftless Area spans Illinois, Iowa, Minnesota, and Wisconsin. Each state's full growing guide is linked on this page.
What other growing regions cover the same states?
Red River Valley, Northwoods (Northern Wisconsin), Shawnee Hills / Southern Illinois (Little Egypt), Southeast Iowa / Great River Region (Mississippi–Des Moines river corner), Loess Hills, and Southeastern Wisconsin Lakeshore (Milwaukee Metro) share at least one state with the Driftless Area. Growing regions overlap and interlock — a single address can sit inside more than one, which is why the precise read is always the parcel, not the region.
What this page reads at the Driftless Area’s own scale
6 of the readings below were taken at the Driftless Area's own scale — the zone 4b-5a band across its footprint, a median 180-day season across its 26 counties and 13,237 documented federal contamination records across its 26 counties, 1,085 of them in Olmsted County alone; one is borrowed from a wider read, named and linked below.
Measured here
- The USDA hardiness band 4b-5a aggregated across all 26 counties in the footprintUSDA PHZM 2023
- The boundary itself — the EPA Level III ecoregion its 26 counties sit inside, drawn where climate and soils changeEPA Level III Ecoregions
- The growing character that makes this region distinct from the states it crossesGrowable Ground subregion registry
- The 28°F season across the footprint — the middle half of its 26 counties run 173 to 185 frost-free days, median 180NOAA Regional Climate Centers ACIS, 1991-2020
- The federal contamination record over the whole footprint — 13,237 documented federal contamination records across its 26 counties, 1,085 of them in Olmsted County aloneEPA, USGS and USDA federal site records
- The soil order mix across the footprint — 63% Alfisols, topsoil pH 5.5–6.7, area-weighted across its 26 mapped countiesUSDA NRCS SSURGO
Inherited from a wider read
- The candidate plant list — all 4 member states' curated sets, merged and filtered to zones 4b-5afrom Illinois, Iowa, Minnesota and Wisconsin
What this page can’t tell you
- Which end of the 12-day range your ground sits at — 173 days at one extreme, 185 at the other, decided mostly by elevationfrost dates explained →
- Which of those soils your own ground sits on — the survey maps them county-wide, and they change across a drivewaysoil types explained →
- The soil pH, drainage, sun hours, and frost pockets on one specific lotwhy one lot differs from the next →
Explore the Driftless Area
State growing guides
Representative counties
Other growing regions across Illinois, Iowa, Minnesota, and Wisconsin
The flat floor of glacial Lake Agassiz along the Red River of the North — deep, dark lakebed clays and one of the coldest, shortest northern seasons on the platform (USDA zones 3b-4b) behind classic sugar-beet, potato, and spring-wheat country.
Wisconsin's coldest, shortest-season tier: the interior forest counties sit at hardiness zones 4a-4b with only 140-158 frost-free days (Florence 140, Sawyer 142, Vilas 143) — roughly two months shorter than the Milwaukee lakeshore. On glaciated northern soils where winter lows reach the -30F floor of zone 4a, Northwoods growers can't inherit the state page's averaged planting dates, variety lists, or perennial ratings — the short interior season sets a different rulebook than the driftless coulees or the lake-warmed Door peninsula to the south.
Illinois's warmest, longest-season ground — and the only unglaciated, hilly corner of the state. Below the Ohio–Mississippi confluence, all 11 counties sit in USDA zone 7a with 220–244 frost-free days (Alexander reaches 244), roughly a full zone warmer and a month longer than the central-Illinois 5b–6a prairie averaged onto the state page. The Shawnee Hills terrain — sandstone ridges, Shawnee National Forest, and the Shawnee Hills AVA (27 CFR §9.206) — trades flat row-crop prairie for slopes, orchards, and vineyards: Union County's Cobden–Anna peach and apple belt and the Shawnee Hills wine trail. Growers here plant weeks earlier and can carry crops that fail statewide — figs, longer-season melons, and tree peaches.
Southeast Iowa's Mississippi–Des Moines river corner is the warm anchor of the state: Lee and Des Moines counties are Iowa's ONLY 6a ground, and the eight-county cluster runs 204–216 frost-free days — roughly 15–27 days past the Iowa median of 189 and up to 48 days longer than the coldest far-north counties (168). That extra window is the length of a real second planting: growers here can genuinely finish sweet potatoes, okra, and long-season melons, and overwinter peach and fig that struggle upstate. So this refines Iowa's 4b–6a state compromise calendar — which sits about three weeks short of Lee County's actual window — rather than restating it.
Western Iowa's Loess Hills are a narrow ridge of wind-blown silt piled up to roughly 200 feet deep along the Missouri River — among the deepest loess deposits on Earth, rivaled only by China's Loess Plateau. That soil grows differently from the rest of Iowa: it drains fast, warms early in spring, and leaves ridgetops droughty while eroding hard on steep south- and west-facing slopes. It's distinctive enough that the TTB drew the Loess Hills District wine region across it in 2016 (27 CFR § 9.255), and cold-hardy grapes now share the slopes with orchards, dry prairie remnants, and terraced market gardens. These seven river-edge counties run zone 5a in the north to 5b in the south, roughly a 180–205 day season — so the calendar below is your honest western-Iowa county window, and the growing notes lean into what loess actually asks of you: cover the slopes, watch the drought on the ridges, and let the fast drainage work for your earliest crops.
Wisconsin's warmest, longest-season corner — and its only zone 6a. Lake Michigan's thermal mass holds the immediate Milwaukee–Racine shore at USDA zone 6a with 216–217 frost-free days (USDA PHZM 2023 + county climate normals), roughly two extra months over the state's northern zone-4 country. The lake buffers spring and fall alike, so a metro or suburban grower here can run warm-season varieties and a planting calendar the statewide "short-season Wisconsin" page never delivers — grading honestly from 6a on the shore to 5b (188–210 frost-free days) across the inland metro and up the Sheboygan–Manitowoc coast. Distinct from Door County's cherry peninsula further north on the same shore.