Yes — Strong Match
hardy geranium (zones 3-9) covers every zone Wisconsin contains (3b-6a), so hardiness is not what limits it anywhere in the state.
Hardy Geranium in Wisconsin — the short answer
Hardy Geranium in Wisconsin: hardy in zones 3–9, part sun, against a state median of ~173 frost-free days.
- Plant zones
- 3-9
- Manual horticultural correction (source not retained); NC State Extension and Missouri Botanical Garden, with the remaining rows from other published sources or Growable Ground compilation
- Wisconsin zones
- 3b-6a
- USDA PHZM 2023
- Frost window
- Apr 17 - May 2 – Oct 9 - Oct 21
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 140 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS and university Extension sources — per-field provenance varies and is published with the dataset.
Your yard isn't the whole zone.
Wisconsin spans zones 3b-6a, but your yard has its own microclimate — slope, trees, and low spots shift frost and sun across a single parcel. Enter your address and we'll score hardy geranium against your land's actual soil, sun, and frost.
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Wisconsin is not one climate
A single Wisconsin answer averages 72 counties whose growing seasons are 77 days apart — from 140 frost-free days in Florence County to 217 in Milwaukee County. Which end of that your land sits nearer changes what hardy geranium can finish before the first hard freeze.
The middle half of 72 counties runs 158–187 days, with a median of 173 days — a 77-day span end to end.
Measured across 72 Wisconsin counties. NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze. Quartiles are order statistics — every figure shown is a value a real county recorded, not an interpolation. Your own site sits somewhere inside this range; a parcel report resolves where.
Where in Wisconsin Fits Best
Even within Wisconsin's zones 3b-6a, county microclimates differ enough to change what thrives. These counties carry the closest zone match for hardy geranium (USDA PHZM 2023):
Zone Comparison
Hardy Geranium Needs
- USDA Zones: 3-9
- Sun: Part Sun
- Mature size: 1.5 ft tall
- Picking window: ~45 days of harvest
- Drought tolerance: Medium
Wisconsin Has
- USDA Zones: 3b-6a
- Last Hard Freeze (28°F): Apr 17 - May 2
- First Hard Freeze (28°F): Oct 9 - Oct 21
- Annual Rainfall: 28-34 inches
- Common Soils: Silt loam, Clay loam, Sandy outwash
Plant Zone Range (zones 3-9)
Plant data: Growable Ground Plant Database, compiled from FAO ECOCROP, USDA PLANTS, and university Extension sources — per-field provenance varies and is published with the dataset. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Hardy Geranium in Wisconsin
The frost window
Across Wisconsin, the last spring hard freeze (28°F) clears between Apr 17 and May 2, and the first fall hard freeze lands between Oct 9 and Oct 21 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 160-day window you can count on — up to 187 days on a mild site in a kind year. That marks the hard freeze, not the last light frost, so tender transplants usually wait another 2-3 weeks.
When to start the seed
Those dates are when hardy geranium goes out, not when it starts. It is sown under cover about 8 weeks ahead, so counting back from Wisconsin's late-side last freeze of May 2 is what fixes your sowing date — and a yard that clears frost earlier than the state's late date starts earlier still.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: Growable Ground Plant Database — frost-free days from FAO ECOCROP, days to harvest from university Extension production guides, and growing-degree-day and chill-hour minimums that are compilation estimates rather than published figures. Your site's own frost dates can run earlier or later than the state range — a parcel report pins them down.
Soil + Drainage Fit
Drainage matters: this plant wants well (dry spells). If your Wisconsin site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Plant pH requirements: FAO ECOCROP and USDA PLANTS, with the remaining rows from other published sources or Growable Ground compilation. Drainage: FAO ECOCROP, with the remaining rows from other published sources or Growable Ground compilation. Wisconsin soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
What Else to Consider for Hardy Geranium in Wisconsin
Zone compatibility tells you about winter cold survival — but Wisconsin growers also need to think about:
Cold winters (-30F in northern WI)
Short growing season (110-140 frost-free days)
Sandy central soils drain too quickly
What to actually do about these — and the constraints that apply to every Wisconsin grower, not just hardy geranium — is covered on the Wisconsin growing guide.
Where in Wisconsin Hardy Geranium Is Zone-Hardy
Hardy Geranium is rated for USDA zones 3–9. Every one of Wisconsin’s 72 counties sits inside that band — from Bayfield County at zone 4a to Racine County at zone 6a — so winter cold is not what decides this plant anywhere in the state. What is left to vary is your own parcel: slope, shelter and cold-air drainage routinely move a site half a zone either way from the county figure.
Across those 72 counties Wisconsin’s winter-low ladder runs from zone 4a in Bayfield County to zone 6a in Racine County — 2 USDA zones of spread, which is 20°F between the two counties’ average coldest night of the year. That is why a statewide hardiness answer is where you start and not where you finish.
The planting window moves with it. Florence County holds its last hard freeze (28°F) until about May 16, while Milwaukee County is clear by Apr 5 — 41 days apart. Set hardy geranium out on your county’s date, not the state’s.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. County last-freeze dates: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F killing freeze — earlier than the folk 32°F "last frost". Hardy Geranium’s zone 3–9 band: USDA PLANTS / Growable Ground plant database. A parcel report resolves your address’s own zone and frost dates rather than its county’s.
Pollinator + Wildlife Value
Hardy Geranium draws honeybees and native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, hardy geranium can only work that bloom inside Wisconsin's frost window — roughly 173 days, opening after the last 28°F freeze (Apr 17 - May 2) and closing at the first (Oct 9 - Oct 21), per NOAA Regional Climate Centers ACIS, 1991-2020.
Wisconsin Cooperative Extension
For Wisconsin-specific cultivar recommendations, planting calendars, and pest pressure for hardy geranium, the canonical source is UW–Madison Division of Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Hardy Geranium native to Wisconsin?
No — the USDA PLANTS Database lists Hardy Geranium as introduced rather than native in the Lower 48, so it is not part of Wisconsin's native flora. It grows here as a garden plant; pairing it with a few Wisconsin natives keeps local pollinators fed too.
Looking for plants that belong here? The Wisconsin growing guide lists USDA-documented natives for the state.
Native-range data: USDA PLANTS Database state-distribution records, accessed 2026-07-01.
Common Questions About Growing Hardy Geranium in Wisconsin
When can I plant Hardy Geranium in Wisconsin?
Wisconsin's last spring hard freeze (28°F) clears between Apr 17 and May 2, and the first fall hard freeze lands between Oct 9 and Oct 21 (NOAA Regional Climate Centers ACIS, 1991-2020). Time outdoor planting to after the last hard freeze for your specific site — a further two to three weeks for anything tender — and count back from those dates for transplant scheduling.
What hardiness zone is Hardy Geranium grown in across Wisconsin?
Wisconsin spans USDA hardiness zones 3b-6a (USDA ARS PHZM 2023). Hardy Geranium carries a range of zones 3-9, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Wisconsin site have?
A typical Wisconsin site sees ~173 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Hardy Geranium should be matched against that window, so check whether your local microclimate runs above or below the state average before settling on a planting date.
Is Hardy Geranium native to Wisconsin?
No — the USDA PLANTS Database lists Hardy Geranium as introduced rather than native in the Lower 48, so it is not part of Wisconsin's native flora. It grows here as a garden plant; pairing it with a few Wisconsin natives keeps local pollinators fed too.
Will Hardy Geranium actually grow on my specific land in Wisconsin?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores hardy geranium against your address's exact soil pH, drainage, sun, and frost-date data drawn from USDA SSURGO, NOAA, and PRISM — not state averages.
Check your specific parcel in Wisconsin
State-level data is a sketch. Your Growable Ground report scores hardy geranium against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Wisconsin hardy geranium averages can't show:
We read public map data around Wisconsin — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Wisconsin hardy geranium average
Explore More
Growing guides for hardy geranium
Explore Wisconsin county by county
Wisconsin carries 72 counties with their own USDA zone — a sample of the growing pages for hardy geranium there:
Where else hardy geranium grows
Hardy Geranium's zone band crosses state lines — these are the states closest to Wisconsin in winter climate where it also has a page, plus the far ends of its range. Each one re-answers the question with that state's own record.
More to grow in Wisconsin
Wisconsin has a growing page for 806 plants — a rotating sample of the rest of the shelf.
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