Opdyke, Illinois, sits in USDA hardiness zone 6b — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
A short list that earns its place here — cabbage, hazelnut, lavender, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Even in Opdyke, 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 Opdyke 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 Opdyke — soil, climate, flood, and parcel records. How we handle your address.
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Opdyke — the short answer
Opdyke, Illinois: USDA zone 6b, about 218 days between hard freezes, across 338 acres of town.
- USDA zone
- 6b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 29
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 2
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~218
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 338 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 Opdyke's average, not your lot's — a low corner or a tree line moves it. Against Opdyke's 218-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Opdyke
Each reading below is measured for Opdyke itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredOpdyke runs about 218 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
MeasuredOpdyke 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 Opdyke is in
Opdyke sits in the Interior River Valleys and Hills — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Opdyke's own centroid rather than borrowed from Jefferson County.
What Grows in Opdyke
Every plant below cleared Opdyke's own zone 6b and its 218-day season. Each card opens that plant's Illinois profile. How we score.
Is it too late to plant in Opdyke?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Mar 1; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 29 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 2 — 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.
What's on the federal record near Opdyke
Closest first, within ~10 miles of Opdyke. Listing isn't leaking, and distance isn't exposure.
- Mount Vernon Il RacgUnderground Storage Tanks · 700 ft
- Jack SmileyUnderground Storage Tanks · 3.1 mi
- Murrel Bernard Grain ElevatorUnderground Storage Tanks · 3.3 mi
- Ten Mile Creek Eads UnitUnderground Storage Tanks · 3.3 mi
- Gateway FSUnderground Storage Tanks · 3.4 mi
- TAYLOR-ATKINSON INCBrownfields · 4.1 mi
- Dodds Comm Cons School Dist #7Underground Storage Tanks · 4.4 mi
- Brehm Oil Co IncUnderground Storage Tanks · 4.4 mi
- Dodds Township OfUnderground Storage Tanks · 4.5 mi
- CARDINAL MFGBrownfields · 5.0 mi
- Homeowners LumberUnderground Storage Tanks · 5.0 mi
- Webber Township Hs Dist 204Underground Storage Tanks · 5.1 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Opdyke'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 Opdyke.
Total Sites
240
within ~10 miles of Opdyke
Risk Level
Elevated
Highest-severity
3 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Opdyke
Severity Distribution
within ~10 miles of Opdyke
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Opdyke, two things run higher than the national average within ~10 miles of Opdyke — CAFO (3 sites) and Underground Storage Tanks (175 sites). 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.
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 Opdyke
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 Opdyke average
Your land is one point inside Opdyke
Everything above resolves to Opdyke as a whole — one PHZM band and one 28°F frost record, read across 338 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 Opdyke Average
Opdyke Average
- ●USDA Zones 6b, averaged across Opdyke
- ●One soil character for all of Opdyke
- ●Frost dates read at Opdyke's scale: Mar 29 to Nov 2
YOUR Parcel
- ✓Your exact zone, not Opdyke's 6b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Opdyke
Pull a site-specific report for your exact address in Opdyke, Illinois — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Opdyke averages can't show:
We read public map data around Opdyke — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Opdyke average
How we know this about Opdyke
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 Opdyke’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 Opdyke
When does frost risk typically end in Opdyke?
The last hard freeze (28°F) in Opdyke typically lands around Mar 29, 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 19.
When is the first frost in Opdyke?
The first hard freeze (28°F) in Opdyke typically arrives around Nov 2, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 19, so the watching starts about Oct 3 — about 218 days after the spring freeze cleared.
How long is the growing season in Opdyke?
Measured between 28°F hard freezes, Opdyke sees about 218 frost-free days — roughly Mar 29 through Nov 2, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 19 to Oct 19, about 183 days.
Is the soil safe to grow vegetables in Opdyke?
The federal record around Opdyke is a meaningful one — 240 documented sites, mostly Underground Storage Tanks entries (175), the nearest Underground Storage Tanks record about 0.1 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 Opdyke?
From about Oct 3 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 2 (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 2. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Opdyke's scale — its 6b band and its 218-day season. Your yard writes its own version of Opdyke'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 Opdyke’s own scale
6 of the readings below were taken at Opdyke's own scale — its own ~218-day season between 28°F freezes, the 338 acres it covers and 240 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Opdyke's own USDA hardiness band, zones 6bUSDA PHZM 2023
- Opdyke's own 28°F hard-freeze dates, about Mar 29 and Nov 2 and the ~218-day span between themNOAA 1991–2020 Climate Normals
- 240 documented contamination sites on the federal record near Opdyke, the closest Underground Storage Tanks record about 0.1 miles out from the town centreFederal environmental registers
- Opdyke's boundary and the 338 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6b and a ~218-day seasonGrowable Ground crop-matching engine
- The ecoregion at Opdyke'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 Opdyke's 338 acres read through its county's SSURGO summaryfrom Jefferson County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Jefferson 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 Jefferson County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Opdyke's 338 acreswhy one lot differs from the next →
- Which side of Opdyke you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 338 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks 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 Opdyke-wide figureread your own land →
More in Illinois
Wider growing context
What grows across IllinoisOpdyke sits outside our named growing regions, so Illinois as a whole is its closest context here.
Nearby growing guides