Unlikely — Zone Mismatch
velvet bean (zones 9-13) does not overlap with Illinois's zone range (5a-7b). Growing outdoors is unlikely without significant protection.
2 zones short — what would close it
Velvet Bean is hardy to zone 9, and the warmest ground in Illinois is zone 7 — 2 zones short. Planted in open ground it will not survive a Illinois winter. To grow it here, grow velvet bean in an earth-sheltered greenhouse — its modeled 2.5-zone lift covers this gap.
An earth-sheltered greenhouse is the lift this needs. How a greenhouse changes what you can grow →
Zone math from 9-13 (plant) against 5-7 (Illinois). Lift modeled by crop_engine.GREENHOUSE_ZONE_MODIFIER_BY_SUBTYPE['earth_sheltered'] (+2.5 zones) via api/fast_sections.py Unlock Engine v2.
Velvet Bean in Illinois — the short answer
Velvet Bean in Illinois: hardy in zones 9–13, full sun, against a state median of ~212 frost-free days.
- Plant zones
- 9-13
- 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
- Illinois zones
- 5a-7b
- USDA PHZM 2023
- Frost window
- Mar 29 - Apr 8 – Oct 28 - Nov 5
- NOAA RCC ACIS 1991-2020, 28°F
- Shortest county season
- 177 days
- NOAA Regional Climate Centers ACIS, 1991-2020, county 28°F killing freeze
- Days to maturity
- 120 days
- Growable Ground Plant Database
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.
Velvet Bean is grown as an annual, so your winter zone isn't the deciding factor — your frost-free window is. A typical Illinois site runs ~212 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 velvet bean against your land's actual frost dates, sun, and soil.
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Illinois is not one climate
A single Illinois answer averages 102 counties whose growing seasons are 67 days apart — from 177 frost-free days in Jo Daviess County to 244 in Alexander County. Which end of that your land sits nearer changes what velvet bean can finish before the first hard freeze.
The middle half of 102 counties runs 203–221 days, with a median of 212 days — a 67-day span end to end.
Measured across 102 Illinois 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 Velvet Bean Stands in Illinois
Velvet Bean is rated for zones 9–13 — a cold floor USDA puts at 20 to 30°F. No Illinois county sits inside it, so in open ground this is a grown-under-cover plant here rather than a bed plant — which is a statement about Illinois winters, not about velvet bean.
Below the zone 9 floor
102 counties
- Carroll County · zone 5a
- Jo Daviess County · zone 5a
- Stephenson County · zone 5a
3 of 102 shown
Winter cold is the limit here — the same plant works in a container that comes under cover.
County hardiness zones: USDA Plant Hardiness Zone Map (PHZM) 2023, per county. A zone is a 10°F band of average annual extreme minimum temperature, so the floor above is the band the plant's rating denotes, not a single measured kill point. Slope, shelter and cold-air drainage routinely move a site half a zone either way from its county figure — which is the part only your address resolves.
Zone Comparison
Velvet Bean Needs
- USDA Zones: 9-13
- Sun: Full Sun
- Mature size: 5 ft tall
- Drought tolerance: Medium
Illinois Has
- USDA Zones: 5a-7b
- Last Hard Freeze (28°F): Mar 29 - Apr 8
- First Hard Freeze (28°F): Oct 28 - Nov 5
- Annual Rainfall: 34-48 inches
- Common Soils: Prairie loam, Silt loam, Clay loam
Plant Zone Range (zones 9-13)
Preferred Soil pH
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 Velvet Bean in Illinois
The frost window
Across Illinois, the last spring hard freeze (28°F) clears between Mar 29 and Apr 8, and the first fall hard freeze lands between Oct 28 and Nov 5 (NOAA Regional Climate Centers ACIS, 1991-2020). Counting from the latest last freeze to the earliest first freeze, that's a 203-day window you can count on — up to 221 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.
Frost tenderness
Velvet Bean is frost-tender — FAO ECOCROP puts its killing temperature at 32°F — so set plants out two to three weeks PAST your local last hard freeze, not on it and not on the state's earliest date. The 28°F marker above is when killing freezes stop, not when light frost does. That is the point where cold damages growing tissue, not a winter-survival floor — an established perennial comes through far colder while dormant, which is what its hardiness zone tells you.
When to start the seed
Velvet Bean is direct-sown where it grows rather than started under cover, so there is no seed-tray head start to bank — Illinois'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 (Growable Ground Plant Database), counting from the last hard freeze it ripens with 83 days to spare even in Illinois's tightest freeze scenario — room for a later start or a second sowing.
Timing tuned to sub-state frost dates — Jo Daviess County, not the statewide average.
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.
Growing Season Fit
The zone check says velvet bean does not survive a Illinois winter in the ground. The season figures below measure a different question — whether it could finish a season here at all — and they only bear on Illinois under protection.
Days to maturity
Velvet Bean matures in ~120 days (Growable Ground Plant Database). A typical Illinois site has ~212 frost-free days, so plenty of room for a second succession.
Growing degree days
Velvet Bean needs ~2500 GDD (base 50°F) to ripen. The state median runs ~3352 GDD (from PRISM 1991-2020 climate normals), so Illinois's typical season clears that easily.
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
Velvet Bean tolerates a wide pH range (pH 4-7.5) — 3.5 units, acid ground through alkaline — so soil acidity is rarely what limits it in Illinois. 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 and 6.5 — worth knowing before you decide whether a Illinois soil test result is a problem or just a number. Drainage matters: this plant wants well (dry spells). If your Illinois site is heavier clay or sits in a low spot, raised beds or amendment with compost solve it.
Your land, not the state average
SSURGO maps about 52.0% of Illinois as poorly or somewhat-poorly drained, and the class flips parcel to parcel. Velvet Bean sits mid-range for drought tolerance, so either extreme can cost you — your soil map unit, not the state average, is the real answer.
Check your parcel → Source: USDA NRCS SSURGO.
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. Illinois soil profile from USDA NRCS SSURGO. Site-specific verification: a 30-minute soil test from your local Extension lab.
What Else to Consider for Velvet Bean in Illinois
Zone compatibility tells you about winter cold survival — but Illinois growers also need to think about:
Heavy clay soils in northern IL drain poorly
Extreme temperature swings between summer and winter
Japanese beetles are a major garden pest
Growing velvet bean here specifically
Velvet Bean roots run medium and prefer pH 4.0–7.5, but drainage comes first here: SSURGO maps about 52.0% of Illinois as poorly or somewhat-poorly drained, and wet ground rots its roots before pH ever matters.
Plant velvet bean on a raised, gravel-amended berm so water drains fast and the roots stays dry. How to handle it →
What to actually do about these — and the constraints that apply to every Illinois grower, not just velvet bean — is covered on the Illinois growing guide.
Timing shifts within Illinois
Illinois isn't one climate. In Jo Daviess County, the last hard freeze (28°F) holds until about Apr 22 — roughly 20 days later than the recorded state median — so plant velvet bean to your county's window, not the statewide date.
Velvet Bean needs about 120 days of frost-free season from planting to harvest. Even Jo Daviess County — Illinois’s shortest season at 177 frost-free days — clears that by 57 days, so season length isn’t the constraint anywhere in Illinois. What varies is your own parcel.
Across Illinois’s 102 counties the frost-free season runs from 177 days in Jo Daviess County to 244 days in Alexander County — a spread of 67 days, which is why a single statewide planting date misleads. The median Illinois county sees 212 frost-free days, leaving velvet bean about 92 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"). Velvet Bean's 120-day requirement: USDA PLANTS / Growable Ground plant database (days to maturity). A parcel report resolves your address's own frost dates.
Pollinator + Wildlife Value
Velvet Bean draws native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, velvet bean can only work that bloom inside Illinois's frost window — roughly 212 days, opening after the last 28°F freeze (Mar 29 - Apr 8) and closing at the first (Oct 28 - Nov 5), per NOAA Regional Climate Centers ACIS, 1991-2020.
Good to Know Before You Plant Velvet Bean
Velvet Bean is listed as toxic to dogs, cats (seeds, pods) at a moderate level (Cornell). Most listed plants only cause brief upset — a raised bed or a fenced corner usually keeps curious pets clear. Worth knowing for placement: in Illinois this is a one-season plant and the first hard freeze (Oct 28 - Nov 5) takes it down, so the exposure above is a summer-long one rather than something standing in the bed all year.
Illinois Cooperative Extension
For Illinois-specific cultivar recommendations, planting calendars, and pest pressure for velvet bean, the canonical source is University of Illinois Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Velvet Bean native to Illinois?
No — the USDA PLANTS Database lists Velvet Bean as introduced rather than native in the Lower 48, so it is not part of Illinois's native flora. It grows here as a garden plant; pairing it with a few Illinois natives keeps local pollinators fed too.
Looking for plants that belong here? The Illinois 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 Velvet Bean in Illinois
When can I plant Velvet Bean in Illinois?
Illinois's last spring hard freeze (28°F) clears between Mar 29 and Apr 8, and the first fall hard freeze lands between Oct 28 and Nov 5 (NOAA Regional Climate Centers ACIS, 1991-2020). Velvet Bean is frost-tender — its killing temperature is 32°F (FAO ECOCROP — the point where cold damages growing tissue, not a winter-survival floor) — so wait two to three weeks past your site's last hard freeze, when light frost has also stopped, before planting out.
Can Velvet Bean mature before first frost in Illinois?
Yes — Velvet Bean matures in 120 days (Growable Ground Plant Database), and Illinois's dependable hard-freeze-free window runs 203 days (NOAA Regional Climate Centers ACIS, 1991-2020), leaving 83 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 Velvet Bean grown in across Illinois?
Illinois spans USDA hardiness zones 5a-7b (USDA ARS PHZM 2023). Velvet Bean carries a range of zones 9-13, so the overlap zones are where outdoor growing is most reliable.
How many frost-free days does a typical Illinois site have?
A typical Illinois site sees ~212 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Velvet Bean 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. In cooler counties like Jo Daviess, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Velvet Bean native to Illinois?
No — the USDA PLANTS Database lists Velvet Bean as introduced rather than native in the Lower 48, so it is not part of Illinois's native flora. It grows here as a garden plant; pairing it with a few Illinois natives keeps local pollinators fed too.
How should I amend the soil for Velvet Bean in Illinois?
Velvet Bean tolerates pH 4-7.5 and well (dry spells) drainage (FAO ECOCROP). That is a 3.5-unit span, acid ground through alkaline, so pH is rarely what limits this plant on a Illinois site — amend for drainage and organic matter first.
Will Velvet Bean actually grow on my specific land in Illinois?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores velvet bean 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 Illinois
State-level data is a sketch. Your Growable Ground report scores velvet bean against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Illinois velvet bean averages can't show:
We read public map data around Illinois — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Illinois velvet bean average
Explore More
Growing guides for velvet bean
Explore Illinois county by county
Illinois carries 102 counties with their own USDA zone — a sample of the growing pages for velvet bean there:
Where else velvet bean grows
Velvet Bean's zone band crosses state lines — these are the states closest to Illinois 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 Illinois
Illinois has a growing page for 893 plants — a rotating sample of the rest of the shelf.
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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