Yes — Strong Match
black-eyed Susan (zones 3-7) covers every zone Illinois contains (5a-7b), so hardiness is not what limits it anywhere in the state.
Black Eyed Susan in Illinois — the short answer
Black Eyed Susan in Illinois: hardy in zones 3–7, full sun, against a state median of ~212 frost-free days.
- Plant zones
- 3-7
- Not verified — NC State Extension Gardener Plant Toolbox lists zones 3a–8b
- 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 has its own microclimate — slope, trees, and low spots shift frost and sun across a single parcel. Enter your address and we'll score black eyed susan 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.
No card required · your parcel report in seconds — read in full free for your first 14 days
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 black eyed susan 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 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 black eyed susan (USDA PHZM 2023):
Zone Comparison
Black Eyed Susan Needs
- USDA Zones: 3-7
- Sun: Full SunWe haven't confirmed this against a published source yet.
- Mature size: 1 ft tall
- Picking window: ~45 days of harvestWe haven't confirmed this against a published source yet.
- 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 3-7)
Preferred Soil pH
We haven't confirmed this against a published source yet.
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 Black Eyed Susan 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
Black Eyed Susan is frost-tender — its killing temperature is 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. We haven't confirmed this against a published source yet.
When to start the seed
Those dates are when black eyed susan 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.
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.
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 black eyed susan survives winter here. Whether the season is long enough — and warm enough — is a different question.
Days to maturity
Black Eyed Susan matures in ~120 days. We haven't confirmed this against a published source yet. A typical Illinois site has ~212 frost-free days, so plenty of room for a second succession.
Growing degree days
Black Eyed Susan needs ~1000 GDD (base 50°F) to ripen. We haven't confirmed this against a published source yet. 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
Black Eyed Susan likes near-neutral soil (pH 5.5-8). That's the common-ground band across Illinois's prairie loam and silt loam — a soil test confirms it for your site. It will grow across that whole span, but it does best between pH 6.5 and 7.5 — 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, a raised bed lifts the roots above wet ground, or work in compost. pH range, preferred pH and drainage need: We haven't confirmed this against a published source yet.
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 Black Eyed Susan 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
What to actually do about these — and the constraints that apply to every Illinois grower, not just black eyed susan — is covered on the Illinois growing guide.
Timing shifts within Illinois
Black Eyed Susan 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 black eyed susan 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"). Black Eyed Susan'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
Black Eyed Susan draws honeybees, native bees, and butterflies (high value). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, black eyed susan 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. Pollinator value: We haven't confirmed this against a published source yet.
Illinois Cooperative Extension
For Illinois-specific cultivar recommendations, planting calendars, and pest pressure for black eyed susan, the canonical source is University of Illinois Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Black Eyed Susan native to Illinois?
The USDA PLANTS Database (accessed 2026-10-19) lists Black Eyed Susan as native to the Lower 48 and records it growing in Illinois, but it does not say whether those Illinois plants are native or introduced. Your state's native plant society or Cooperative Extension can tell you whether it is part of the local flora.
State records: USDA PLANTS Database state-distribution data (presence, not state-level nativity), accessed 2026-10-19.
Common Questions About Growing Black Eyed Susan in Illinois
When can I plant Black Eyed Susan 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). 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 Black Eyed Susan mature before first frost in Illinois?
Yes — Black Eyed Susan 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 Black Eyed Susan grown in across Illinois?
Illinois spans USDA hardiness zones 5a-7b (USDA ARS PHZM 2023). Black Eyed Susan carries a range of zones 3-7, 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). Black Eyed Susan 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 Black Eyed Susan native to Illinois?
The USDA PLANTS Database (accessed 2026-10-19) lists Black Eyed Susan as native to the Lower 48 and records it growing in Illinois, but it does not say whether those Illinois plants are native or introduced. Your state's native plant society or Cooperative Extension can tell you whether it is part of the local flora.
How should I amend the soil for Black Eyed Susan in Illinois?
Black Eyed Susan prefers pH 5.5-8 and well (dry spells) drainage. We haven't confirmed this against a published source yet. 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 Black Eyed Susan actually grow on my specific land in Illinois?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores black eyed susan against your address's mapped 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 black eyed susan against your land's mapped soil, modelled sun, drainage, and frost data — not zone averages.
Three things about your lot that Illinois black eyed susan 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 black eyed susan average
Explore More
Growing guides for black eyed susan
Explore Illinois county by county
Illinois carries 102 counties with their own USDA zone — a sample of the growing pages for black eyed susan there:
Where else black eyed susan grows
Black Eyed Susan'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 889 plants — a rotating sample of the rest of the shelf.
Last updated: