Yes — Strong Match
wild bergamot (zones 3-9) covers every zone Illinois contains (5a-7b), so hardiness is not what limits it anywhere in the state.
Wild Bergamot in Illinois — the short answer
Wild Bergamot in Illinois: hardy in zones 3–9, part sun, against a state median of ~212 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
- 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.
Illinois spans zones 5a-7b, but your yard sits in exactly one — and slope, tree cover, and cold-air pockets nudge it further. Enter your address and we'll score wild bergamot against your parcel's actual hardiness, soil, and sun.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Illinois is not one climate
Illinois’s winter-low ladder runs across 102 counties, from zone 5 in Carroll County to zone 7 in Williamson County. That is 20°F between the two counties’ average coldest night — the difference between wild bergamot overwintering in the ground and coming under cover.
The middle half of 102 counties runs 5.5–6.5 zones, with a median of 6 zones — a 2-zone span end to end.
Measured across 102 Illinois counties. USDA PHZM 2023, per county. 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 Illinois Fits Best
Even within Illinois's zones 5a-7b, county microclimates differ enough to change what thrives. These counties carry the closest zone match for wild bergamot (USDA PHZM 2023):
Zone Comparison
Wild Bergamot Needs
- USDA Zones: 3-9
- Frost-Free Days: 110+
- Sun: Part Sun
- Mature size: 3.5 ft tall
- Picking window: ~45 days of harvest
- Drought tolerance: Low
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 3-9)
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 Wild Bergamot 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.
When to start the seed
Those dates are when wild bergamot goes out, not when it starts. It is sown under cover about 8 weeks ahead, so counting back from Illinois's late-side last freeze of Apr 8 is what fixes your sowing date — and a yard that clears frost earlier than the state's late date starts earlier still.
Winter standing
Illinois runs as cold as USDA zone 5, and no sourced winter-hardiness floor is on record for wild bergamot, so this page does not state whether it overwinters here — and gives no fall establishment date on the strength of a guess. Whether wild bergamot is a permanent planting or a replant-every-spring crop for you turns on your own zone within Illinois; check its hardiness range against that before treating it as long-lived ground.
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 wild bergamot survives winter here. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Wild Bergamot wants 110+ frost-free days; a typical Illinois site sees ~212 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves comfortable headroom for succession planting.
Growing degree days
Wild Bergamot needs ~1000 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
Wild Bergamot likes near-neutral soil (pH 6.5-8.5). That's the common-ground band across Illinois's prairie loam and silt loam — a soil test confirms it for your site.
Your land, not the state average
Illinois's soils run mostly silt loam, but SSURGO maps the series, texture, and drainage under your exact parcel. What matters for wild bergamot is the horizon its roots actually work, not the surface. That map unit, not the state average, decides how wild bergamot performs.
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 Wild Bergamot 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 wild bergamot here specifically
Illinois's soils run mostly silt loam (Alfisols), and whether that suits wild bergamot's pH 6.5–8.5 preference comes down to your exact parcel, not the statewide picture.
Pull your parcel's SSURGO map unit, test pH, and amend toward wild bergamot's 6.5–8.5 target before planting. How to handle it →
What to actually do about these — and the constraints that apply to every Illinois grower, not just wild bergamot — 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 wild bergamot to your county's window, not the statewide date.
Wild Bergamot needs about 110 days of frost-free season to complete its cycle. Even Jo Daviess County — Illinois’s shortest season at 177 frost-free days — clears that by 67 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 wild bergamot about 102 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"). Wild Bergamot's 110-day requirement: USDA PLANTS / Growable Ground plant database (minimum frost-free days). A parcel report resolves your address's own frost dates.
Pollinator + Wildlife Value
Wild Bergamot draws honeybees, native bees, butterflies, and hummingbirds (high value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, wild bergamot 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.
Recommended Wild Bergamot Varieties for Illinois
Illinois publishes no state variety trial for wild bergamot, so we won't invent a "best for Illinois" list. Choose types rated to your USDA hardiness zone (5a-7b), and confirm winter survival and drainage against your own parcel.
Illinois Cooperative Extension
For Illinois-specific cultivar recommendations, planting calendars, and pest pressure for wild bergamot, the canonical source is University of Illinois Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Wild Bergamot native to Illinois?
Yes — the USDA PLANTS Database (accessed 2026-07-01) documents Wild Bergamot as native to Illinois. Planting it supports the pollinators and wildlife that evolved alongside it.
Native-range data: USDA PLANTS Database state-distribution records, accessed 2026-07-01.
Common Questions About Growing Wild Bergamot in Illinois
When can I plant Wild Bergamot 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). No sourced winter-hardiness floor is on record for Wild Bergamot, so this page does not state whether it overwinters in Illinois and publishes no fall establishment date for it — check its hardiness range against your own zone before treating it as a permanent planting.
What hardiness zone is Wild Bergamot grown in across Illinois?
Illinois spans USDA hardiness zones 5a-7b (USDA ARS PHZM 2023). Wild Bergamot 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 Illinois site have?
A typical Illinois site sees ~212 frost-free days per year (derived from NOAA Regional Climate Centers ACIS, 1991-2020). Wild Bergamot needs 110+ 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 Jo Daviess, the freeze-free season runs shorter than the state average, so verify your own county's window.
Is Wild Bergamot native to Illinois?
Yes — the USDA PLANTS Database (accessed 2026-07-01) documents Wild Bergamot as native to Illinois. Planting it supports the pollinators and wildlife that evolved alongside it.
How should I amend the soil for Wild Bergamot in Illinois?
Wild Bergamot prefers pH 6.5-8.5 (USDA PLANTS). That sits in the common-ground band across Illinois soils — a 30-minute soil test from a local Extension lab confirms it for your specific site.
Will Wild Bergamot actually grow on my specific land in Illinois?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores wild bergamot 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 wild bergamot against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Illinois wild bergamot 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 wild bergamot average
Explore More
Growing guides for wild bergamot
Explore Illinois county by county
Illinois carries 102 counties with their own USDA zone — a sample of the growing pages for wild bergamot there:
Where else wild bergamot grows
Wild Bergamot'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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