Yes — Strong Match
Roman chamomile (zones 3-9) covers every zone Illinois contains (5a-7b), so hardiness is not what limits it anywhere in the state.
Roman Chamomile in Illinois — the short answer
Roman Chamomile in Illinois: hardy in zones 3–9, full 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
- 90 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 roman chamomile 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 roman chamomile 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 roman chamomile (USDA PHZM 2023):
Zone Comparison
Roman Chamomile Needs
- USDA Zones: 3-9
- Frost-Free Days: 180+
- Sun: Full Sun
- Mature size: 6 in tall
- Picking window: ~60 days of harvest
- 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 3-9)
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 Roman Chamomile 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 roman chamomile 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.
Establishment timing
As a long-lived plant, roman chamomile isn't racing the calendar to a harvest date. Plant it in spring once the last hard-freeze window passes so roots settle in through the full season, or in early fall while the soil still holds summer warmth.
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 roman chamomile survives winter here. Whether the season is long enough — and warm enough — is a different question.
Frost-free days
Roman Chamomile wants 180+ frost-free days; a typical Illinois site sees ~212 (NOAA Regional Climate Centers ACIS, 1991-2020). That leaves a workable window — start indoors to bank time.
Growing degree days
Roman Chamomile needs ~700 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
Roman Chamomile 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 and 7 — 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. Roman Chamomile 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.
Before you plant roman chamomile 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 roman chamomile 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.
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 Roman Chamomile 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 roman chamomile here specifically
Roman Chamomile roots run shallow and prefer pH 5.5–8.0, but drainage comes first here: SSURGO maps about 52.0% of Illinois as poorly or somewhat-poorly drained, and wet ground rots its crown before pH ever matters.
Plant roman chamomile on a raised, gravel-amended berm so water drains fast and the crown stays dry. How to handle it →
What to actually do about these — and the constraints that apply to every Illinois grower, not just roman chamomile — 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 roman chamomile to your county's window, not the statewide date.
Roman Chamomile needs about 180 days of frost-free season to complete its cycle. 100 of Illinois’s 102 counties give it that outright. The tightest that does is Stephenson County at 188 frost-free days — 8 to spare. Below that line you are transplanting or extending the season, not direct-sowing.
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 roman chamomile about 32 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"). Roman Chamomile's 180-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
Roman Chamomile draws honeybees and native bees (moderate value, Growable Ground Plant Database). Planting it near vegetable beds can lift fruit set on neighboring crops. Outdoors, roman chamomile 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 Roman Chamomile Varieties for Illinois
Illinois publishes no state variety trial for roman chamomile, 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 roman chamomile, the canonical source is University of Illinois Extension. Their fact sheets carry the local trial data we can't generalize across 50 states.
Is Roman Chamomile native to Illinois?
No — the USDA PLANTS Database lists Roman Chamomile 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 Roman Chamomile in Illinois
When can I plant Roman Chamomile 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). Roman Chamomile is a long-lived planting, so target spring just after your local last hard freeze — or early fall while the soil holds warmth — and let it establish through the season.
What hardiness zone is Roman Chamomile grown in across Illinois?
Illinois spans USDA hardiness zones 5a-7b (USDA ARS PHZM 2023). Roman Chamomile 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). Roman Chamomile needs 180+ 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 Roman Chamomile native to Illinois?
No — the USDA PLANTS Database lists Roman Chamomile 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 Roman Chamomile in Illinois?
Roman Chamomile prefers pH 5.5-8 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 Roman Chamomile actually grow on my specific land in Illinois?
State-level zone + climate data is a sketch. A Growable Ground parcel report scores roman chamomile 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 roman chamomile against your parcel's exact soil, sun, drainage, and frost data — not zone averages.
Three things about your lot that Illinois roman chamomile 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 roman chamomile average
Explore More
Growing guides for roman chamomile
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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