Hartford, Illinois, sits in USDA hardiness zone 7a — a zone band wide enough that plant choice, not possibility, is the interesting question.
Crops well matched to these conditions include cabbage, hazelnut, california poppy, and collard greens — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Even in Hartford, 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 Hartford 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 Hartford — soil, climate, flood, and parcel records. How we handle your address.
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Hartford — the short answer
Hartford, Illinois: USDA zone 7a, about 236 days between hard freezes, across 3K acres of town.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 23
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 14
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~236
- 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 7a is Hartford's average, not your lot's — a low corner or a tree line moves it. Against Hartford's 236-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Hartford
Each reading below is measured for Hartford itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredHartford runs about 236 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
MeasuredHartford sits in USDA hardiness zone 7a.
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 Hartford is in
Hartford sits in the Interior River Valleys and Hills — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Hartford's own centroid rather than borrowed from Madison County.
What Grows in Hartford
Every plant below cleared Hartford's own zone 7a and its 236-day season. Each card opens that plant's Illinois profile. How we score.
Is it too late to plant in Hartford?
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 23; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 23 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 14 — long-season crops need about 90 days of runway, quick greens only 30. With a season this long, “too late” mostly means “switch crops” — second sowings and a full fall garden are the norm, with garlic closing the year.
Documented around Hartford
Survey cells within 31 miles of Hartford checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 226 miles off. What to watch for.
What's on the federal record near Hartford
Closest first, within ~10 miles of Hartford. Listing isn't leaking, and distance isn't exposure.
- PHILLIPS 66 COMPANYBrownfields · 550 ft
- PHILLIPS 66 COMPANYToxics Release Inventory · 550 ft
- PHILLIPS 66 HARTFORD LUBRICANTSBrownfields · 1100 ft
- Piasa Motor Fuels BulkplantUnderground Storage Tanks · 1400 ft
- Fas Mart #5154Underground Storage Tanks · 1700 ft
- OMEGA PARTNERS HARTFORD, LLCBrownfields · 2000 ft
- OMEGA PARTNERS HARTFORD, LLCToxics Release Inventory · 2000 ft
- FLINT HILLS RESOURCES PINE BEND LLCBrownfields · 2000 ft
- MIDWEST MOTOR SPORTSBrownfields · 2100 ft
- SCHIBER TRUCK CO., INC.Brownfields · 2300 ft
- SENTINEL TRANSPORTATION LLCBrownfields · 0.5 mi
- Center Terminal Co.Underground Storage Tanks · 0.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Hartford'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 Hartford.
Sources Checked
within ~10 miles of Hartford
Severity Distribution
within ~10 miles of Hartford
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Hartford, two things run higher than the national average within ~10 miles of Hartford — Toxics Release Inventory (72 sites) and Superfund (14 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check your specific parcel in Hartford
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 Hartford average
Your land is one point inside Hartford
Everything above resolves to Hartford 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 Hartford Average
Hartford Average
- ●USDA Zones 7a, averaged across Hartford
- ●One soil character for all of Hartford
- ●Frost dates read at Hartford's scale: Mar 23 to Nov 14
YOUR Parcel
- ✓Your exact zone, not Hartford's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Hartford
Pull a site-specific report for your exact address in Hartford, Illinois — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Hartford averages can't show:
We read public map data around Hartford — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Hartford average
How we know this about Hartford
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 Hartford’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 Hartford
When does frost risk typically end in Hartford?
The last hard freeze (28°F) in Hartford typically lands around Mar 23, 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 13.
When is the first frost in Hartford?
The first hard freeze (28°F) in Hartford typically arrives around Nov 14, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 31, so the watching starts about Oct 15 — about 236 days after the spring freeze cleared.
How long is the growing season in Hartford?
Measured between 28°F hard freezes, Hartford sees about 236 frost-free days — roughly Mar 23 through Nov 14, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 13 to Oct 31, about 201 days.
Is the soil safe to grow vegetables in Hartford?
The federal record around Hartford runs heavier than most — 1,115 documented sites, mostly Underground Storage Tanks entries (620), the nearest Brownfields record about 0.1 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 Hartford?
From about Oct 15 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 14 (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 14. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Hartford's scale — its 7a band and its 236-day season. Your yard writes its own version of Hartford'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 Hartford’s own scale
7 of the readings below were taken at Hartford's own scale — its own ~236-day season between 28°F freezes, the 3,329 acres it covers and 1,115 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Hartford's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Hartford's own 28°F hard-freeze dates, about Mar 23 and Nov 14 and the ~236-day span between themNOAA 1991–2020 Climate Normals
- 1,115 documented contamination sites on the federal record near Hartford, the closest Brownfields record about 0.1 miles out from the town centreFederal environmental registers
- Hartford's boundary and the 3,329 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~236-day seasonGrowable Ground crop-matching engine
- The ecoregion at Hartford's own centroid, the Interior River Valleys and HillsUS EPA Level III Ecoregions
- Lanternfly survey cells around Hartford 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 Hartford's 3,329 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 Hartford's 3,329 acreswhy one lot differs from the next →
- Which side of Hartford you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 3,329 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.1 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 Hartford-wide figureread your own land →
More in Illinois
Wider growing context
What grows across IllinoisHartford sits outside our named growing regions, so Illinois as a whole is its closest context here.
Nearby growing guides