Flossmoor, Illinois, sits in USDA hardiness zone 6a — a zone band wide enough that plant choice, not possibility, is the interesting question.
Crops well matched to these conditions include cabbage, hazelnut, lavender, and collard greens — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Even in Flossmoor, no two yards are alike.
A low spot, a south-facing slope, or a stand of trees moves the frost date and sun across a single Flossmoor lot. Enter your address and we'll score 1,086 plants against your land's actual soil, sun, and frost.
We read public map data around Flossmoor — soil, climate, flood, and parcel records. How we handle your address.
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Flossmoor — the short answer
Flossmoor, Illinois: USDA zone 6a, about 216 days between hard freezes, across 2K acres of town.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 5
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 7
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~216
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 2K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 6a is Flossmoor's average, not your lot's — a low corner or a tree line moves it. Against Flossmoor's 216-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Flossmoor
Each reading below is measured for Flossmoor itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredFlossmoor runs about 216 days between hard freezes — a long growing season.
There is slack for succession plantings and slow-finishing crops: many vegetables can be sown twice, and the heat-lovers have time to ripen fully.
Plan a second sowing of quick crops after the first comes out, and use the fall window most gardeners let sit idle.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredFlossmoor sits in USDA hardiness zone 6a.
The zone sets which perennials, shrubs, and fruit trees live through an average winter here — a plant rated for a colder zone is a safe bet, one rated warmer needs winter protection or gets treated as an annual.
Match perennials and fruit to the zone before you buy, so nothing you plant is a gamble against the cold.
USDA PHZM 2023
The kind of country Flossmoor is in
Flossmoor sits in the Central Corn Belt Plains — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Flossmoor's own centroid rather than borrowed from Cook County.
What Grows in Flossmoor
Every plant below cleared Flossmoor's own zone 6a and its 216-day season. Each card opens that plant's Illinois profile. How we score.
Is it too late to plant in Flossmoor?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Mar 8; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 5 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 7 — long-season crops need about 90 days of runway, quick greens only 30. Here the season winds down slowly: late sowings, a real autumn harvest, and garlic in the ground before the first hard freeze.
Documented around Flossmoor
Spotted lanternfly documented 12 miles from Flossmoor, first recorded 2023. What to watch for.
What's on the federal record near Flossmoor
Closest first, within ~10 miles of Flossmoor. Listing isn't leaking, and distance isn't exposure.
- FLOSSMOORPFAS · 400 ft
- Village of FlossmoorUnderground Storage Tanks · 1300 ft
- FLOSSMOOR VILLAGE OFBrownfields · 1300 ft
- Flossmoor Service Station, Inc.Underground Storage Tanks · 1400 ft
- Mike Flossmoor 66 IncUnderground Storage Tanks · 2100 ft
- Cherry Hills CC IncUnderground Storage Tanks · 2600 ft
- CVS CAREMARK #48067Brownfields · 2600 ft
- FLOSSMOR PUBLIC WORKSBrownfields · 0.7 mi
- 35N13E-12.2b1Nitrate · 0.7 mi
- HOMEWOOD FLOSSMOOR PARK DISTRICTBrownfields · 0.7 mi
- Homewood Flossmoor Park DistUnderground Storage Tanks · 0.7 mi
- VOLLMER ROAD RESEVOIRBrownfields · 0.8 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Flossmoor's center, not your beds. Run your own address for what's upwind of you specifically.
Environmental Intelligence
The counts behind that headline — every source type on the record near Flossmoor.
Total Sites
2,505
within ~10 miles of Flossmoor
Risk Level
High
Highest-severity
49 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Flossmoor
Severity Distribution
within ~10 miles of Flossmoor
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Flossmoor, two things run higher than the national average within ~10 miles of Flossmoor — PFAS (38 sites) and Superfund (49 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check your specific parcel in Flossmoor
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,086 plant recommendations.
25+ data sources read at your address, not the Flossmoor average
Your land is one point inside Flossmoor
Everything above resolves to Flossmoor as a whole — one PHZM band and one 28°F frost record, read across 2K acres. Your parcel is one point inside that footprint. Slope, tree cover, a low spot that pools cold air, and what is in the soil are all resolved at the address, and none of them are visible at town scale. That is the honest boundary of this page, and the reason the next step is a reading of your own ground rather than a better local average.
Your Lot vs the Flossmoor Average
Flossmoor Average
- ●USDA Zones 6a, averaged across Flossmoor
- ●One soil character for all of Flossmoor
- ●Frost dates read at Flossmoor's scale: Apr 5 to Nov 7
YOUR Parcel
- ✓Your exact zone, not Flossmoor's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Flossmoor
Pull a site-specific report for your exact address in Flossmoor, Illinois — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Flossmoor averages can't show:
We read public map data around Flossmoor — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Flossmoor average
How we know this about Flossmoor
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this town’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Flossmoor’s own record; boundaries and acreage from US Census TIGER/Line 2025; the contamination records from the federal sources named in their beats above. Soil is not read at town grain anywhere on this page — there is no town-resolution survey in our data, which is why you will find no soil grid here rather than a statewide one wearing a local label. The resolution ledger below names every figure this page inherited.
Common questions about Flossmoor
When does frost risk typically end in Flossmoor?
The last hard freeze (28°F) in Flossmoor typically lands around Apr 5, per NOAA 1991–2020 climate normals — earlier than the light-frost dates most charts quote. That marks the hard freeze, not the last light frost — lighter frosts keep biting past it, which is why tender transplants here wait until about Apr 26.
When is the first frost in Flossmoor?
The first hard freeze (28°F) in Flossmoor typically arrives around Nov 7, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 24, so the watching starts about Oct 8 — about 216 days after the spring freeze cleared.
How long is the growing season in Flossmoor?
Measured between 28°F hard freezes, Flossmoor sees about 216 frost-free days — roughly Apr 5 through Nov 7, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 26 to Oct 24, about 181 days.
Is the soil safe to grow vegetables in Flossmoor?
The federal record around Flossmoor runs heavier than most — 2,505 documented sites, mostly Underground Storage Tanks entries (1,267), the nearest PFAS record under a tenth of a mile out — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
How do I protect my plants from frost in Flossmoor?
From about Oct 8 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Nov 7 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Nov 7. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Flossmoor's scale — its 6a band and its 216-day season. Your yard writes its own version of Flossmoor's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
What this page reads at Flossmoor’s own scale
7 of the readings below were taken at Flossmoor's own scale — its own ~216-day season between 28°F freezes, the 2,346 acres it covers and 2,505 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Flossmoor's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Flossmoor's own 28°F hard-freeze dates, about Apr 5 and Nov 7 and the ~216-day span between themNOAA 1991–2020 Climate Normals
- 2,505 documented contamination sites on the federal record near Flossmoor, the closest PFAS record under a tenth of a mile out from the town centreFederal environmental registers
- Flossmoor's boundary and the 2,346 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~216-day seasonGrowable Ground crop-matching engine
- The ecoregion at Flossmoor's own centroid, the Central Corn Belt PlainsUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of Flossmoorlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Flossmoor's 2,346 acres read through its county's SSURGO summaryfrom Cook County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Cook County
- The growing challenges every Illinois grower plans around — written at state scale, so they stay on the state guidefrom Illinois
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Cook County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Flossmoor's 2,346 acreswhy one lot differs from the next →
- Which side of Flossmoor you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 2,346 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest PFAS record under a tenth of a mile out, measured from the town centrehow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — measured at your address, and averaged away by any Flossmoor-wide figureread your own land →