Conditional — Some Areas
chiltepin pepper (zones 7-11) reaches only part of Illinois (5a-7b): zone 7 are in range, so where you are in the state decides it.
Chiltepin Pepper in Illinois — the short answer
Chiltepin Pepper in Illinois: hardy in zones 7–11, full sun, against a state median of ~212 frost-free days.
- Plant zones
- 7-11
- 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 has its own microclimate — slope, trees, and low spots shift frost and sun across a single parcel. Enter your address and we'll score chiltepin pepper 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.
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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 chiltepin pepper 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
Chiltepin Pepper is rated for zones 7–11 — a cold floor USDA puts at 0 to 10°F. Against Illinois’s 102 counties that band holds in 18 of them, and the line runs at Alexander County (zone 7a), the coldest county still inside it.
Inside zones 7–11
18 counties
- Franklin County · zone 7a
- Gallatin County · zone 7a
- Hardin County · zone 7a
3 of 18 shown
Below the zone 7 floor
84 counties
- Carroll County · zone 5a
- Jo Daviess County · zone 5a
- Stephenson County · zone 5a
3 of 84 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.
Even within Illinois's zones 5a-7b, county microclimates differ enough to change what thrives. These counties carry the closest zone match for chiltepin pepper (USDA PHZM 2023):
Zone Comparison
Chiltepin Pepper Needs
- USDA Zones: 7-11
- Frost-Free Days: 60+
- Sun: Full Sun
- Mature size: 3 ft tall
- Picking window: ~60 days of harvest
- Drought tolerance: High
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 7-11)
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 Chiltepin Pepper 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 chiltepin pepper goes out, not when it starts. It is sown under cover about 10 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 chiltepin pepper survives winter in part of Illinois, not across all of it. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Chiltepin Pepper wants 60+ 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
Chiltepin Pepper 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
Chiltepin Pepper likes near-neutral soil (pH 4.5-7). 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 5.5 and 6.8 — 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.
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.
Before you plant chiltepin pepper for food
Anything you grow to eat takes up what is in the ground it grows in, so what is on record near you is worth knowing before chiltepin pepper goes in. What follows is Illinois’s documented federal record at state scale — a screening signal, not a soil test, and not a statement about any one lot.
Safe to Grow Here?
What the federal record shows across Illinois — and how to grow with it.
We checked the federal record across Illinois — 52,971 documented sites across 8 of the 9 source types we track.
The most significant on record: 622 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Illinois carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Sources Checked
across Illinois
Severity Distribution
across Illinois
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Illinois, two things run higher than the national average across Illinois — PFAS (482 sites) and Toxics Release Inventory (3,504 sites). That's not a problem with your land — it's information about it.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What Else to Consider for Chiltepin Pepper 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 chiltepin pepper — is covered on the Illinois growing guide.
Timing shifts within Illinois
Chiltepin Pepper needs about 60 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 117 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 chiltepin pepper about 152 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"). Chiltepin Pepper's 60-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
Chiltepin Pepper draws honeybees and native bees (low value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, chiltepin pepper 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.
Illinois Cooperative Extension
For Illinois-specific cultivar recommendations, planting calendars, and pest pressure for chiltepin pepper, the canonical source is University of Illinois Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Common Questions About Growing Chiltepin Pepper in Illinois
When can I plant Chiltepin Pepper 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 Chiltepin Pepper mature before first frost in Illinois?
Yes — Chiltepin Pepper 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 Chiltepin Pepper grown in across Illinois?
Illinois spans USDA hardiness zones 5a-7b (USDA ARS PHZM 2023). Chiltepin Pepper carries a range of zones 7-11, 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). Chiltepin Pepper needs 60+ frost-free days, so check whether your local microclimate runs above or below the state average before settling on a planting date.
How should I amend the soil for Chiltepin Pepper in Illinois?
Chiltepin Pepper prefers pH 4.5-7 and well (dry spells) drainage (FAO ECOCROP). 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 Chiltepin Pepper actually grow on my specific land in Illinois?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores chiltepin pepper 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 chiltepin pepper against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Illinois chiltepin pepper 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 chiltepin pepper average
Explore More
Growing guides for chiltepin pepper
Explore Illinois county by county
Illinois carries 102 counties with their own USDA zone — a sample of the growing pages for chiltepin pepper there:
Where else chiltepin pepper grows
Chiltepin Pepper'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.
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