Generally — Most Areas
annual lespedeza (zones 5-9) suits most of Wisconsin (3b-6a) — zones 5-6 are in range, and the rest of the state is the exception.
Your yard isn't the whole zone.
Annual Lespedeza is grown as an annual, so your winter zone isn't the deciding factor — your frost-free window is. A typical Wisconsin site runs ~173 frost-free days, but that is a state median, not your yard: slope, trees, and low spots move the last-frost date across a single parcel. Enter your address and we'll score annual lespedeza against your land's actual frost dates, sun, and soil.
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Zone Comparison
Annual Lespedeza Needs
- USDA Zones: 5-9
- Frost-Free Days: 120+
- Sun: Full Sun
- Mature size: 1.5 ft tall
- Drought tolerance: High
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 5-9)
Preferred Soil pH
Plant data: USDA PLANTS Database / Growable Ground plant catalog. State data: USDA ARS PHZM 2023, NOAA Climate Normals, NRCS SSURGO.
When to Plant Annual Lespedeza 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
Annual Lespedeza is direct-sown where it grows rather than started under cover, so there is no seed-tray head start to bank — Wisconsin's dates above are the whole calendar for it. That makes the last-freeze date the binding constraint, and a warmer pocket of your own yard is worth more to this crop than it is to a transplanted one.
Days to maturity vs. the window
At 120 days to maturity (USDA PLANTS Database), counting from the last hard freeze it ripens with 40 days to spare even in Wisconsin's tightest freeze scenario — room for a later start or a second sowing.
Timing tuned to sub-state frost dates — Florence County, not the statewide average.
Frost window: NOAA Climate Normals 1991-2020. Plant timing fields: USDA PLANTS Database. Your site's own frost dates can run earlier or later than the state range — a parcel report pins them down.
Growing Season Fit
The zone check says annual lespedeza survives winter in part of Wisconsin, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Annual Lespedeza wants 120+ frost-free days; a typical Wisconsin site sees ~173 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves a workable window — start indoors to bank time.
Growing degree days
Annual Lespedeza needs ~1800 GDD (base 50°F) to ripen. The state median runs ~2102 GDD (from PRISM 1991-2020 climate normals), so Wisconsin sits right at the threshold — pay attention to siting and microclimate.
GDD and chill-hour figures are computed from PRISM 1991-2020 monthly climate normals; frost-free days from NOAA Regional Climate Centers ACIS, 1991-2020. Each is the state median across its counties (P25/P75 span the within-state spread). Hardiness-zone range is USDA PHZM 2023.
Soil + Drainage Fit
Annual Lespedeza tolerates a wide pH range (pH 5-8) — 3 units, acid ground through alkaline — so soil acidity is rarely what limits it in Wisconsin. A soil test is still worth having, but for what else it tells you about this site, not to clear this plant. It will grow across that whole span, but it does best between pH 5.5 and 6 — worth knowing before you decide whether a Wisconsin soil test result is a problem or just a number. 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.
Your land, not the state average
Wisconsin's soils run mostly silt loam, but SSURGO maps the series, texture, and drainage under your exact parcel. What matters for annual lespedeza is the horizon its roots actually work, not the surface. That map unit, not the state average, decides how annual lespedeza performs.
Check your parcel → Source: USDA NRCS SSURGO.
Plant pH and drainage requirements from USDA PLANTS Database. Wisconsin soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
Annual Lespedeza in Wisconsin — Quick Answer
- Verdict: Generally — Most Areas
- Plant Zones: 5-9 (USDA PLANTS Database)
- State Zones: 3b-6a (USDA ARS PHZM 2023)
- Growing Season: 28°F hard freezes about Apr 17 - May 2 to Oct 9 - Oct 21 (NOAA Regional Climate Centers ACIS, 1991-2020)
- Days to Maturity: 120 days
What Else to Consider for Annual Lespedeza 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
Growing annual lespedeza here specifically
Annual Lespedeza needs pH 5.0–8.0; Wisconsin's dominant silt loam soils may or may not deliver that, so your parcel's SSURGO map unit is the real test.
Start with a soil test on your own ground and adjust pH and texture to fit annual lespedeza's 5.0–8.0 range. How to handle it →
What to actually do about these — and the constraints that apply to every Wisconsin grower, not just annual lespedeza — is covered on the Wisconsin growing guide.
Timing shifts within Wisconsin
Wisconsin isn't one climate. In Florence County, the last hard freeze (28°F) holds until about May 16 — roughly 21 days later than the recorded state median — so plant annual lespedeza to your county's window, not the statewide date.
Annual Lespedeza needs about 120 days of frost-free season to complete its cycle. Even Florence County — Wisconsin’s shortest season at 140 frost-free days — clears that by 20 days, so season length isn’t the constraint anywhere in Wisconsin. What varies is your own parcel.
Across Wisconsin’s 72 counties the frost-free season runs from 140 days in Florence County to 217 days in Milwaukee County — a spread of 77 days, which is why a single statewide planting date misleads. The median Wisconsin county sees 173 frost-free days, leaving annual lespedeza about 53 days of slack on a typical parcel — room for a second sowing where the season runs long.
County last-freeze dates and frost-free day counts: NOAA Regional Climate Centers ACIS (1991-2020), county 28°F freeze (earlier than the folk 32°F "last frost"). Annual Lespedeza's 120-day requirement: USDA PLANTS / Growable Ground plant database (minimum frost-free days). A parcel report resolves your address's own frost dates.
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 annual lespedeza (USDA PHZM 2023):
Pollinator + Wildlife Value
Annual Lespedeza draws honeybees and native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, annual lespedeza 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 annual lespedeza, 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 Annual Lespedeza native to Wisconsin?
No — the USDA PLANTS Database lists Annual Lespedeza 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 Annual Lespedeza in Wisconsin
When can I plant Annual Lespedeza 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.
Can Annual Lespedeza mature before first frost in Wisconsin?
Yes — Annual Lespedeza matures in 120 days (USDA PLANTS Database), and Wisconsin's dependable hard-freeze-free window runs 160 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 40 days of margin. Plant once the last hard freeze has passed — two to three weeks later for anything tender — and it ripens ahead of the first fall freeze.
What hardiness zone is Annual Lespedeza grown in across Wisconsin?
Wisconsin spans USDA hardiness zones 3b-6a (USDA ARS PHZM 2023). Annual Lespedeza carries a range of zones 5-9, 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). Annual Lespedeza needs 120+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date. In cooler counties like Florence, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Annual Lespedeza native to Wisconsin?
No — the USDA PLANTS Database lists Annual Lespedeza 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.
How should I amend the soil for Annual Lespedeza in Wisconsin?
Annual Lespedeza tolerates pH 5-8 and well (dry spells) drainage (Growable Ground Plant Database). That is a 3-unit span, acid ground through alkaline, so pH is rarely what limits this plant on a Wisconsin site — amend for drainage and organic matter first.
Will Annual Lespedeza actually grow on my specific land in Wisconsin?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores annual lespedeza 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 annual lespedeza against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Wisconsin annual lespedeza 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 annual lespedeza average
Explore More
Growing guides for annual lespedeza
Analysis by the Growable Ground research team, grounded in USDA PLANTS, USDA NRCS SSURGO, NOAA Climate Normals (1991-2020), and named Cooperative Extension sources. How we know →
Cite this dataset
Kirchick, M. (2026). Growable Ground Plant Database [Data set]. Zenodo. https://doi.org/10.5281/zenodo.21435643
Licensed CC BY-NC 4.0. DOI 10.5281/zenodo.21435643
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