Round Lake Park, Illinois, sits in USDA hardiness zone 5b — a zone band wide enough that plant choice, not possibility, is the interesting question.
These conditions suit cabbage, cranberry, lavender, and collard greens — a starting list any specific site will trim or extend with its own soil, sun, and drainage.
Even in Round Lake Park, 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 Round Lake Park 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 Round Lake Park — soil, climate, flood, and parcel records. How we handle your address.
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Round Lake Park — the short answer
Round Lake Park, Illinois: USDA zone 5b, about 197 days between hard freezes, across 1K acres of town.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 13
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 27
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~197
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 1K 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 5b is Round Lake Park's average, not your lot's — a low corner or a tree line moves it. Against Round Lake Park's 197-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Round Lake Park
Each reading below is measured for Round Lake Park itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredRound Lake Park runs about 197 days between hard freezes — a moderate growing season.
There is room for the full run of cool-season crops plus a warm-season main crop, but the calendar is tight enough that a late spring or early fall frost still decides how much finishes.
Time warm-season transplants to your last hard freeze, and a few weeks of season extension turns a near-miss harvest into a sure one.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredRound Lake Park sits in USDA hardiness zone 5b.
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 Round Lake Park is in
Round Lake Park sits in the Southeastern Wisconsin Till Plains — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Round Lake Park's own centroid rather than borrowed from Lake County.
What Grows in Round Lake Park
Every plant below cleared Round Lake Park's own zone 5b and its 197-day season. Each card opens that plant's Illinois profile. How we score.
Is it too late to plant in Round Lake Park?
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 16; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 13 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 27 — long-season crops need about 90 days of runway, quick greens only 30. The tail of the season still works: sixty-day crops into late summer, quick greens after, garlic last of all.
Documented around Round Lake Park
Spotted lanternfly documented 20 miles from Round Lake Park, first recorded 2023. What to watch for.
What's on the federal record near Round Lake Park
Closest first, within ~10 miles of Round Lake Park. Listing isn't leaking, and distance isn't exposure.
- Drywall SupplierUnderground Storage Tanks · 1400 ft
- BELLE AIRE CREATIONSToxics Release Inventory · 1700 ft
- BELLE AIRE CREATIONSBrownfields · 1700 ft
- WALMARK CORPBrownfields · 1700 ft
- WHYTE GATE INCBrownfields · 1800 ft
- S & S Petroleum Products #110Underground Storage Tanks · 1800 ft
- BAXTER HEALTHCARE CORPBrownfields · 2200 ft
- BAXTER HEALTHCARE CORPToxics Release Inventory · 2200 ft
- Avon Twp Hwy DeptUnderground Storage Tanks · 0.6 mi
- B & M AUTO BODYBrownfields · 0.6 mi
- COLLISION SOLUTIONBrownfields · 0.6 mi
- Auto CentralUnderground Storage Tanks · 0.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Round Lake Park'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 Round Lake Park.
Sources Checked
within ~10 miles of Round Lake Park
Severity Distribution
within ~10 miles of Round Lake Park
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Round Lake Park, PFAS runs higher than the national average — 18 sites within ~10 miles of Round Lake Park. 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.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Check your specific parcel in Round Lake Park
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 Round Lake Park average
Your land is one point inside Round Lake Park
Everything above resolves to Round Lake Park as a whole — one PHZM band and one 28°F frost record, read across 1K 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 Round Lake Park Average
Round Lake Park Average
- ●USDA Zones 5b, averaged across Round Lake Park
- ●One soil character for all of Round Lake Park
- ●Frost dates read at Round Lake Park's scale: Apr 13 to Oct 27
YOUR Parcel
- ✓Your exact zone, not Round Lake Park's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Round Lake Park
Pull a site-specific report for your exact address in Round Lake Park, Illinois — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Round Lake Park averages can't show:
We read public map data around Round Lake Park — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Round Lake Park average
How we know this about Round Lake Park
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 Round Lake Park’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 Round Lake Park
When does frost risk typically end in Round Lake Park?
The last hard freeze (28°F) in Round Lake Park typically lands around Apr 13, 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 May 4.
When is the first frost in Round Lake Park?
The first hard freeze (28°F) in Round Lake Park typically arrives around Oct 27, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 13, so the watching starts about Sep 27 — about 197 days after the spring freeze cleared.
How long is the growing season in Round Lake Park?
Measured between 28°F hard freezes, Round Lake Park sees about 197 frost-free days — roughly Apr 13 through Oct 27, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 4 to Oct 13, about 162 days.
Is the soil safe to grow vegetables in Round Lake Park?
The federal record around Round Lake Park runs heavier than most — 1,231 documented sites, mostly Underground Storage Tanks entries (614), the nearest Underground Storage Tanks record about 0.3 miles 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 Round Lake Park?
From about Sep 27 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 Oct 27 (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 Oct 27. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Round Lake Park's scale — its 5b band and its 197-day season. Your yard writes its own version of Round Lake Park'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 Round Lake Park’s own scale
7 of the readings below were taken at Round Lake Park's own scale — its own ~197-day season between 28°F freezes, the 1,323 acres it covers and 1,231 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Round Lake Park's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Round Lake Park's own 28°F hard-freeze dates, about Apr 13 and Oct 27 and the ~197-day span between themNOAA 1991–2020 Climate Normals
- 1,231 documented contamination sites on the federal record near Round Lake Park, the closest Underground Storage Tanks record about 0.3 miles out from the town centreFederal environmental registers
- Round Lake Park's boundary and the 1,323 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~197-day seasonGrowable Ground crop-matching engine
- The ecoregion at Round Lake Park's own centroid, the Southeastern Wisconsin Till PlainsUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of Round Lake Parklydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Round Lake Park's 1,323 acres read through its county's SSURGO summaryfrom Lake County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Lake 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 Lake County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Round Lake Park's 1,323 acreswhy one lot differs from the next →
- Which side of Round Lake Park you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,323 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.3 miles 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 Round Lake Park-wide figureread your own land →