Joslin, Illinois, sits in USDA hardiness zone 5b — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
Growers here do well with cabbage, blueberry, lavender, and collard greens — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Even in Joslin, 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 Joslin 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 Joslin — soil, climate, flood, and parcel records. How we handle your address.
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Joslin — the short answer
Joslin, Illinois: USDA zone 5b, about 205 days between hard freezes, across 3K acres of town.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 7
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 29
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~205
- 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 5b is Joslin's average, not your lot's — a low corner or a tree line moves it. Against Joslin's 205-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Joslin
Each reading below is measured for Joslin itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredJoslin runs about 205 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
MeasuredJoslin 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 Joslin is in
Joslin sits in the Interior River Valleys and Hills — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Joslin's own centroid rather than borrowed from Rock Island County.
What Grows in Joslin
Every plant below cleared Joslin's own zone 5b and its 205-day season. Each card opens that plant's Illinois profile. How we score.
Is it too late to plant in Joslin?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Mar 10; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 7 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 29 — long-season crops need about 90 days of runway, quick greens only 30. A long window like this one runs successions deep into fall — and even its last weeks take quick greens and garlic.
What's on the federal record near Joslin
Closest first, within ~10 miles of Joslin. Listing isn't leaking, and distance isn't exposure.
- TYSON FRESH MEATS INC - JOSLIN ILToxics Release Inventory · 0.5 mi
- TYSON FRESH MEATS INC - JOSLIN ILBrownfields · 0.5 mi
- 34th Ave NNitrate · 1.3 mi
- Midway Stone Co IncUnderground Storage Tanks · 2.9 mi
- 66th Ave N and 300th St NNitrate · 3.0 mi
- A & M Country StoreUnderground Storage Tanks · 3.6 mi
- WESLEY DECLERCQ FARMCAFO · 3.8 mi
- Mobil StationUnderground Storage Tanks · 3.9 mi
- Circus ShopUnderground Storage Tanks · 3.9 mi
- Curnyn Construction CoUnderground Storage Tanks · 3.9 mi
- COUNTER HILLS DAIRYCAFO · 4.3 mi
- Blackhawk Foundation CoUnderground Storage Tanks · 4.4 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Joslin'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 Joslin.
Total Sites
177
within ~10 miles of Joslin
Risk Level
Elevated
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of Joslin
Severity Distribution
within ~10 miles of Joslin
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Joslin, CAFO runs higher than the national average — 11 sites within ~10 miles of Joslin. Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Check your specific parcel in Joslin
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 Joslin average
Your land is one point inside Joslin
Everything above resolves to Joslin 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 Joslin Average
Joslin Average
- ●USDA Zones 5b, averaged across Joslin
- ●One soil character for all of Joslin
- ●Frost dates read at Joslin's scale: Apr 7 to Oct 29
YOUR Parcel
- ✓Your exact zone, not Joslin's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Joslin
Pull a site-specific report for your exact address in Joslin, Illinois — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Joslin averages can't show:
We read public map data around Joslin — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Joslin average
How we know this about Joslin
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 Joslin’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 Joslin
When does frost risk typically end in Joslin?
The last hard freeze (28°F) in Joslin typically lands around Apr 7, 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 28.
When is the first frost in Joslin?
The first hard freeze (28°F) in Joslin typically arrives around Oct 29, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 15, so the watching starts about Sep 29 — about 205 days after the spring freeze cleared.
How long is the growing season in Joslin?
Measured between 28°F hard freezes, Joslin sees about 205 frost-free days — roughly Apr 7 through Oct 29, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 28 to Oct 15, about 170 days.
Is the soil safe to grow vegetables in Joslin?
The federal record around Joslin is a meaningful one — 177 documented sites, mostly Underground Storage Tanks entries (104), the nearest Toxics Release Inventory record about 0.5 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 Joslin?
From about Sep 29 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 29 (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 29. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Joslin's scale — its 5b band and its 205-day season. Your yard writes its own version of Joslin'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 Joslin’s own scale
6 of the readings below were taken at Joslin's own scale — its own ~205-day season between 28°F freezes, the 2,972 acres it covers and 177 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Joslin's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Joslin's own 28°F hard-freeze dates, about Apr 7 and Oct 29 and the ~205-day span between themNOAA 1991–2020 Climate Normals
- 177 documented contamination sites on the federal record near Joslin, the closest Toxics Release Inventory record about 0.5 miles out from the town centreFederal environmental registers
- Joslin's boundary and the 2,972 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~205-day seasonGrowable Ground crop-matching engine
- The ecoregion at Joslin's own centroid, the Interior River Valleys and HillsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Joslin's 2,972 acres read through its county's SSURGO summaryfrom Rock Island County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Rock Island 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 Rock Island County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Joslin's 2,972 acreswhy one lot differs from the next →
- Which side of Joslin you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 2,972 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Toxics Release Inventory record about 0.5 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 Joslin-wide figureread your own land →
More in Illinois
Wider growing context
What grows across IllinoisJoslin sits outside our named growing regions, so Illinois as a whole is its closest context here.
Nearby growing guides