Portage County, in Wisconsin, sits in USDA hardiness zone 5a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
A short list that earns its place here — cranberry, cherry, potato, and ginseng — with any one site's soil, sun, and drainage making the final cut.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Portage County holds more than one microclimate.
Soils and elevations shift across Portage County, so your frost dates and drainage aren't the county average. Enter your address and we'll score 1,112 plants against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Quick Facts
USDA Zones
5a
Last Hard Freeze (28°F)
Apr 16
County normal — light frosts run a few weeks later
First Hard Freeze (28°F)
Oct 30
County normal — light frosts arrive a few weeks earlier
County Area
513K acres
Hardiness Zone Range
Zone maps are averages across Portage County. Your yard's slope, trees, and frost pockets shift what actually grows — see your land's exact reading.
Soil in Portage County
Across Portage County, the ground is predominantly Alfisols, where Richford, Rosholt, and Newson are the most extensive named soil series. The soil is generally well drained with a loamy sand surface. Topsoil pH runs about 5.3–6.2, moderately acidic. Rainfall drains through hydrologic group A soils.
Soil order
Alfisols
Drainage
Well drained
Prime farmland
18%
Hydric soils
24%
Soil still varies lot by lot — soil types explained.
What Grows in Portage County
Plants matched to Portage County's USDA zones 5a — each links to its full growing profile.
Is it too late to plant in Portage County?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 19; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 16 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 30 — 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.
Growing Challenges in Wisconsin
What an experienced grower plans around here — each one has a move.
Cold winters (-30F in northern WI)
Plant perennials rated for the cold you actually get — northern Wisconsin rewards zone honesty with decades of returns.
Short growing season (110-140 frost-free days)
Indoor starts plus a cold frame stretch the season on both ends — standard practice from Madison to Superior.
Sandy central soils drain too quickly
The Central Sands fix is organic matter — compost and cover crops, every year, until the ground holds its own water.
For cultivar selection, pest pressure, and planting-time guidance specific to Wisconsin, the UW–Madison Division of Extension is the authoritative local source.
Safe to Grow Here?
What the federal record shows across Portage County — and how to grow with it.
We checked the federal record across Portage County — 958 documented sites across 7 of the 9 source types we track.
The most significant on record: 1 Superfund site. 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 Portage 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.
Environmental Intelligence
Understanding what's nearby helps you make informed decisions about where and how to grow.
Sources Checked
across Portage County
Severity Distribution
across Portage County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Portage County, Nitrate runs higher than the national average — 284 sites nearby. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Portage County
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,112 plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Your Specific Parcel Matters
Portage County Average
- ●USDA Zones 5a
- ●Generic soil type for the area
- ●State-average frost dates
YOUR Parcel
- ✓Your exact hardiness zone
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Portage County
Pull a site-specific report for your exact address in Portage County, Wisconsin — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Key Growing Facts for Portage County, Wisconsin
- USDA Hardiness Zones: 5a (USDA PHZM 2023)
- Last Hard Freeze (28°F): Apr 16 (county normal, NOAA 1991–2020 Climate Normals — light frosts can follow for a few weeks)
- First Hard Freeze (28°F): Oct 30 (county normal, NOAA 1991–2020 Climate Normals — light frosts can arrive a few weeks earlier)
- Days Between Hard Freezes: ~197 (county normal, NOAA 1991–2020 Climate Normals)
- County Land Area: 513K acres (US Census TIGER 2025)
Zone data: USDA ARS Plant Hardiness Zone Map 2023. Climate data: NOAA NCEI. County boundaries: US Census TIGER/Line 2025.
Frost dates here are the Portage County average. Low spots and tree cover move them by days on any one yard — see your exact frost windows.
Frequently Asked Questions
What hardiness zone is Portage County, Wisconsin?
Portage County sits in USDA hardiness zone 5a, per the USDA Plant Hardiness Zone Map 2023. Zones reflect average annual extreme minimum temperatures from 1991–2020 weather data.
Is it too late to plant in Portage County?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 19; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 16 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 30 — 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.
When does frost risk typically end in Portage County?
The last hard freeze (28°F) in Portage County typically lands around Apr 16, per NOAA 1991–2020 climate normals — an earlier marker than the light-frost dates many planting charts quote. That marks the hard freeze, not the last light frost — light frosts can still bite for a few more weeks, so tender transplants usually wait another 2–3 weeks.
How long is the growing season in Portage County?
Measured between 28°F hard freezes, Portage County sees about 197 frost-free days — roughly Apr 16 through Oct 30, per NOAA 1991–2020 climate normals. Tender crops get a somewhat shorter practical window, since lighter frosts reach a few weeks past the hard-freeze dates on both ends.
What vegetables grow in Portage County?
Portage County's zone 5a supports a wide range — strong performers include Cranberry, Cherry, Potato, Ginseng, and Sugar Maple. What actually takes on any one site comes down to its soil, sun, and drainage, and we score each plant against the real conditions at your address.
Which hardiness zone is Portage County, really?
Officially, Portage County sits in USDA zone 5a (USDA PHZM 2023) — but a zone is a 30-year average of winter's coldest night across an area, and it can't see any one yard. A south-facing slope, a tree line, or a low frost pocket can shift a single site by half a zone either way, which is why neighboring gardeners often quote different numbers. We read the conditions at your exact address — soil, sun, slope, and frost — and score 1,112 plants against what's actually there.
Is the soil safe to grow vegetables in Portage County?
The federal record around Portage County is a meaningful one — 958 documented sites — 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.
Just moved to Portage County — what should I know before planting?
Start with three facts. Portage County sits in USDA zone 5a, which sets what survives winter; the last 28°F hard freeze typically clears around Apr 16, with about 197 frost-free days to work with (NOAA 1991–2020 climate normals); and 958 documented sites sit on the federal record here, so a soil test before food beds is the smart first step. From there, matching plants to your actual soil and sun is the fun part.
Everything on this page is a Portage County average. Your yard writes its own version — 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 Wisconsin's frost window, season length, and soil profile against the plant's real requirements.