Twin Grove, Illinois, sits in USDA hardiness zone 6a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
On paper, cabbage, hazelnut, lavender, and collard greens all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Even in Twin Grove, 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 Twin Grove 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 Twin Grove — soil, climate, flood, and parcel records. How we handle your address.
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Twin Grove — the short answer
Twin Grove, Illinois: USDA zone 6a, about 204 days between hard freezes, across 3K acres of town.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 9
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 30
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~204
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 3K 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 Twin Grove's average, not your lot's — a low corner or a tree line moves it. Against Twin Grove's 204-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Twin Grove
Each reading below is measured for Twin Grove itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredTwin Grove runs about 204 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
MeasuredTwin Grove 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 Twin Grove is in
Twin Grove sits in the Central Corn Belt Plains — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Twin Grove's own centroid rather than borrowed from McLean County.
What Grows in Twin Grove
Every plant below cleared Twin Grove's own zone 6a and its 204-day season. Each card opens that plant's Illinois profile. How we score.
Is it too late to plant in Twin Grove?
Usually not — gardeners here simply switch what goes in the ground as the season moves. Cool-season crops can go in from around Mar 12; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 9 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 30 — 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.
What's on the federal record near Twin Grove
Closest first, within ~10 miles of Twin Grove. Listing isn't leaking, and distance isn't exposure.
- Don Loeffler IncUnderground Storage Tanks · 2.0 mi
- Carri Scharf Trucking, Inc.Underground Storage Tanks · 2.6 mi
- 23N 1E- 6.8h1Nitrate · 2.7 mi
- APL Logistics, Inc.Underground Storage Tanks · 2.8 mi
- Circle K #1251Underground Storage Tanks · 3.0 mi
- FEDEX NATIONAL LTLBrownfields · 3.0 mi
- TRACTOR SUPPLY CO 102Brownfields · 3.1 mi
- MITSUBISHI MOTORS NORTH AMERICA INCBrownfields · 3.2 mi
- MITSUBISHI MOTORS NORTH AMERICA INCToxics Release Inventory · 3.2 mi
- WAL-MART SUPERCENTER 3459Brownfields · 3.2 mi
- Murphy USA #6827Underground Storage Tanks · 3.3 mi
- CALIBER COLLISION CENTERBrownfields · 3.5 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Twin Grove'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 Twin Grove.
Total Sites
469
within ~10 miles of Twin Grove
Risk Level
Elevated
Highest-severity
15 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Twin Grove
Severity Distribution
within ~10 miles of Twin Grove
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
- •TRI facilities report what they release. Check the wind — downwind beds catch more of it.
Check your specific parcel in Twin Grove
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 Twin Grove average
Your land is one point inside Twin Grove
Everything above resolves to Twin Grove as a whole — one PHZM band and one 28°F frost record, read across 3K 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 Twin Grove Average
Twin Grove Average
- ●USDA Zones 6a, averaged across Twin Grove
- ●One soil character for all of Twin Grove
- ●Frost dates read at Twin Grove's scale: Apr 9 to Oct 30
YOUR Parcel
- ✓Your exact zone, not Twin Grove's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Twin Grove
Pull a site-specific report for your exact address in Twin Grove, Illinois — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Twin Grove averages can't show:
We read public map data around Twin Grove — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Twin Grove average
How we know this about Twin Grove
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 Twin Grove’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 Twin Grove
When does frost risk typically end in Twin Grove?
The last hard freeze (28°F) in Twin Grove typically lands around Apr 9, 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 30.
When is the first frost in Twin Grove?
The first hard freeze (28°F) in Twin Grove typically arrives around Oct 30, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 16, so the watching starts about Sep 30 — about 204 days after the spring freeze cleared.
How long is the growing season in Twin Grove?
Measured between 28°F hard freezes, Twin Grove sees about 204 frost-free days — roughly Apr 9 through Oct 30, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 30 to Oct 16, about 169 days.
Is the soil safe to grow vegetables in Twin Grove?
The federal record around Twin Grove is a meaningful one — 469 documented sites, mostly Underground Storage Tanks entries (283), the nearest Underground Storage Tanks record about 2.0 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 Twin Grove?
From about Sep 30 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 30 (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 30. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Twin Grove's scale — its 6a band and its 204-day season. Your yard writes its own version of Twin Grove'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 Twin Grove’s own scale
6 of the readings below were taken at Twin Grove's own scale — its own ~204-day season between 28°F freezes, the 2,537 acres it covers and 469 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Twin Grove's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Twin Grove's own 28°F hard-freeze dates, about Apr 9 and Oct 30 and the ~204-day span between themNOAA 1991–2020 Climate Normals
- 469 documented contamination sites on the federal record near Twin Grove, the closest Underground Storage Tanks record about 2.0 miles out from the town centreFederal environmental registers
- Twin Grove's boundary and the 2,537 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~204-day seasonGrowable Ground crop-matching engine
- The ecoregion at Twin Grove's own centroid, the Central Corn Belt PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Twin Grove's 2,537 acres read through its county's SSURGO summaryfrom McLean County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom McLean 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 McLean County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Twin Grove's 2,537 acreswhy one lot differs from the next →
- Which side of Twin Grove you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 2,537 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 2.0 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 Twin Grove-wide figureread your own land →
More in Illinois
Wider growing context
What grows across IllinoisTwin Grove sits outside our named growing regions, so Illinois as a whole is its closest context here.
Nearby growing guides