Oelwein, Iowa, sits in USDA hardiness zone 5a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
These conditions suit cabbage, cranberry, lavender, and collard greens — a starting list any specific site will trim or extend with its own soil, sun, and drainage.
Even in Oelwein, 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 Oelwein 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 Oelwein — soil, climate, flood, and parcel records. How we handle your address.
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Oelwein — the short answer
Oelwein, Iowa: USDA zone 5a, about 185 days between hard freezes, across 3K acres of city.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 16
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 18
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~185
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City 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 5a is Oelwein's average, not your lot's — a low corner or a tree line moves it. Against Oelwein's 185-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Oelwein
Each reading below is measured for Oelwein itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredOelwein runs about 185 days between hard freezes — a moderate growing season.
There is room for the full run of cool-season crops plus a warm-season main crop, but the calendar is tight enough that a late spring or early fall frost still decides how much finishes.
Time warm-season transplants to your last hard freeze, and a few weeks of season extension turns a near-miss harvest into a sure one.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredOelwein sits in USDA hardiness zone 5a.
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 Oelwein is in
Oelwein sits in the Western Corn Belt Plains — EPA Level III, inside the wider Great Plains. That is read at Oelwein's own centroid rather than borrowed from Fayette County.
What Grows in Oelwein
Every plant below cleared Oelwein's own zone 5a and its 185-day season. Each card opens that plant's Iowa profile. How we score.
Is it too late to plant in Oelwein?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Mar 19; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 16 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 18 — long-season crops need about 90 days of runway, quick greens only 30. Late in the year the fall bench takes over — quick greens, radishes, and garlic that repays you next summer.
What's on the federal record near Oelwein
Closest first, within ~10 miles of Oelwein. Listing isn't leaking, and distance isn't exposure.
- FORMER JIM''S QUICK SHOPUnderground Storage Tanks · 300 ft
- WARE & MCDONALD OIL CO #447Underground Storage Tanks · 450 ft
- CITY OF OELWEINUnderground Storage Tanks · 600 ft
- WALKER CONSTUnderground Storage Tanks · 700 ft
- COLONIAL BAKING COUnderground Storage Tanks · 800 ft
- SUPER MARTUnderground Storage Tanks · 900 ft
- XL SPECIALIZED TRAILERS INCToxics Release Inventory · 950 ft
- KWIK STAR #665Underground Storage Tanks · 1000 ft
- ROGGE MACHINE SHOPUnderground Storage Tanks · 1100 ft
- BEAVER SERVICE & REPAIRUnderground Storage Tanks · 1200 ft
- ARNOLD MOTOR SUPPLYBrownfields · 1500 ft
- ABCO ENGINEERING CORPBrownfields · 1600 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Oelwein'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 Oelwein.
Total Sites
155
within ~10 miles of Oelwein
Risk Level
Moderate
Highest-severity
9 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Oelwein
Severity Distribution
within ~10 miles of Oelwein
Highest-Severity Sites
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
Check your specific parcel in Oelwein
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 Oelwein average
Your land is one point inside Oelwein
Everything above resolves to Oelwein 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 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 Oelwein Average
Oelwein Average
- ●USDA Zones 5a, averaged across Oelwein
- ●One soil character for all of Oelwein
- ●Frost dates read at Oelwein's scale: Apr 16 to Oct 18
YOUR Parcel
- ✓Your exact zone, not Oelwein's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Oelwein
Pull a site-specific report for your exact address in Oelwein, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Oelwein averages can't show:
We read public map data around Oelwein — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Oelwein average
How we know this about Oelwein
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 Oelwein’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 Oelwein
When does frost risk typically end in Oelwein?
The last hard freeze (28°F) in Oelwein typically lands around Apr 16, 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 May 7.
When is the first frost in Oelwein?
The first hard freeze (28°F) in Oelwein typically arrives around Oct 18, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 4, so the watching starts about Sep 18 — about 185 days after the spring freeze cleared.
How long is the growing season in Oelwein?
Measured between 28°F hard freezes, Oelwein sees about 185 frost-free days — roughly Apr 16 through Oct 18, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 7 to Oct 4, about 150 days.
Is the soil safe to grow vegetables in Oelwein?
The federal record around Oelwein shows 155 documented sites, mostly Underground Storage Tanks entries (81), the nearest Underground Storage Tanks record under a tenth of a mile out — a typical footprint for a growing area, and proximity to a documented site is information, not a diagnosis of any one yard. It's worth seeing which recorded sites sit closest to where you grow, and testing the soil before new food beds near any of them.
How do I protect my plants from frost in Oelwein?
From about Sep 18 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 18 (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 18. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Oelwein's scale — its 5a band and its 185-day season. Your yard writes its own version of Oelwein'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 Oelwein’s own scale
6 of the readings below were taken at Oelwein's own scale — its own ~185-day season between 28°F freezes, the 3,081 acres it covers and 155 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Oelwein's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Oelwein's own 28°F hard-freeze dates, about Apr 16 and Oct 18 and the ~185-day span between themNOAA 1991–2020 Climate Normals
- 155 documented contamination sites on the federal record near Oelwein, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Oelwein's boundary and the 3,081 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~185-day seasonGrowable Ground crop-matching engine
- The ecoregion at Oelwein's own centroid, the Western Corn Belt PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Oelwein's 3,081 acres read through its county's SSURGO summaryfrom Fayette County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Fayette County
- The growing challenges every Iowa grower plans around — written at state scale, so they stay on the state guidefrom Iowa
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Fayette County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Oelwein's 3,081 acreswhy one lot differs from the next →
- Which side of Oelwein you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 3,081 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record under a tenth of a mile 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 Oelwein-wide figureread your own land →
More in Iowa
Wider growing context
What grows across IowaOelwein sits outside our named growing regions, so Iowa as a whole is its closest context here.