Highland, Illinois, sits in USDA hardiness zone 6b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
The conditions favor cabbage, hazelnut, lavender, and collard greens, among others — though every individual site edits that list with its own soil, sun, and drainage.
Even in Highland, 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 Highland 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 Highland — soil, climate, flood, and parcel records. How we handle your address.
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Highland — the short answer
Highland, Illinois: USDA zone 6b, about 224 days between hard freezes, across 5K acres of city.
- USDA zone
- 6b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 27
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 6
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~224
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 5K 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 6b is Highland's average, not your lot's — a low corner or a tree line moves it. Against Highland's 224-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Highland
Each reading below is measured for Highland itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredHighland runs about 224 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
MeasuredHighland sits in USDA hardiness zone 6b.
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 Highland is in
Highland sits in the Interior River Valleys and Hills — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Highland's own centroid rather than borrowed from Madison County.
What Grows in Highland
Every plant below cleared Highland's own zone 6b and its 224-day season. Each card opens that plant's Illinois profile. How we score.
Is it too late to plant in Highland?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Feb 27; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 27 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 6 — long-season crops need about 90 days of runway, quick greens only 30. There is slack in a calendar like this — late plantings, second rounds of favorites, and a fall bench that keeps beds working.
Documented around Highland
Survey cells within 31 miles of Highland checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 219 miles off. What to watch for.
What's on the federal record near Highland
Closest first, within ~10 miles of Highland. Listing isn't leaking, and distance isn't exposure.
- HIGHLAND WTPBrownfields · 0.6 mi
- Highland RadioUnderground Storage Tanks · 0.6 mi
- HIGHLAND SUPPLY CORPToxics Release Inventory · 0.7 mi
- HIGHLAND SUPPLY CORPBrownfields · 0.7 mi
- WALMART SUPERCENTER 435Brownfields · 0.8 mi
- Murphy USA #6643Underground Storage Tanks · 0.8 mi
- TRI FORD MERCURY INCBrownfields · 0.9 mi
- BASLER ELECTRIC COBrownfields · 1.0 mi
- Highland High SchoolUnderground Storage Tanks · 1.1 mi
- Circle K #1352Underground Storage Tanks · 1.2 mi
- HSHS ST JOSEPHS HOSPITALBrownfields · 1.3 mi
- St. Joseph's Critical Access HospitalUnderground Storage Tanks · 1.3 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Highland'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 Highland.
Total Sites
153
within ~10 miles of Highland
Risk Level
Elevated
Highest-severity
2 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Highland
Severity Distribution
within ~10 miles of Highland
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Highland, two things run higher than the national average within ~10 miles of Highland — CAFO (9 sites) and Underground Storage Tanks (94 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Highland
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 Highland average
Your land is one point inside Highland
Everything above resolves to Highland as a whole — one PHZM band and one 28°F frost record, read across 5K 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 city 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 Highland Average
Highland Average
- ●USDA Zones 6b, averaged across Highland
- ●One soil character for all of Highland
- ●Frost dates read at Highland's scale: Mar 27 to Nov 6
YOUR Parcel
- ✓Your exact zone, not Highland's 6b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Highland
Pull a site-specific report for your exact address in Highland, Illinois — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Highland averages can't show:
We read public map data around Highland — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Highland average
How we know this about Highland
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Highland’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 city grain anywhere on this page — there is no city-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 Highland
When does frost risk typically end in Highland?
The last hard freeze (28°F) in Highland typically lands around Mar 27, 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 17.
When is the first frost in Highland?
The first hard freeze (28°F) in Highland typically arrives around Nov 6, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 23, so the watching starts about Oct 7 — about 224 days after the spring freeze cleared.
How long is the growing season in Highland?
Measured between 28°F hard freezes, Highland sees about 224 frost-free days — roughly Mar 27 through Nov 6, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 17 to Oct 23, about 189 days.
Is the soil safe to grow vegetables in Highland?
The federal record around Highland is a meaningful one — 153 documented sites, mostly Underground Storage Tanks entries (94), the nearest Brownfields record about 0.6 miles out — so a soil test before new food beds is a sensible precaution here, not a reason to hold back from growing. Remember that proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what sits where.
How do I protect my plants from frost in Highland?
From about Oct 7 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 6 (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 6. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Highland's scale — its 6b band and its 224-day season. Your yard writes its own version of Highland'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 Highland’s own scale
7 of the readings below were taken at Highland's own scale — its own ~224-day season between 28°F freezes, the 4,580 acres it covers and 153 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Highland's own USDA hardiness band, zones 6bUSDA PHZM 2023
- Highland's own 28°F hard-freeze dates, about Mar 27 and Nov 6 and the ~224-day span between themNOAA 1991–2020 Climate Normals
- 153 documented contamination sites on the federal record near Highland, the closest Brownfields record about 0.6 miles out from the town centreFederal environmental registers
- Highland's boundary and the 4,580 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6b and a ~224-day seasonGrowable Ground crop-matching engine
- The ecoregion at Highland's own centroid, the Interior River Valleys and HillsUS EPA Level III Ecoregions
- Lanternfly survey cells around Highland checked, none carrying a detectionlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Highland's 4,580 acres read through its county's SSURGO summaryfrom Madison County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Madison 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 Madison County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Highland's 4,580 acreswhy one lot differs from the next →
- Which side of Highland you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 4,580 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.6 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 Highland-wide figureread your own land →
More in Illinois
Wider growing context
What grows across IllinoisHighland sits outside our named growing regions, so Illinois as a whole is its closest context here.