Decorah, Iowa, sits in USDA hardiness zone 5a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
A short list that earns its place here — cabbage, cranberry, lavender, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Even in Decorah, 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 Decorah 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 Decorah — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Decorah — the short answer
Decorah, Iowa: USDA zone 5a, about 191 days between hard freezes, across 5K acres of city.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 14
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 22
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~191
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 5K 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 Decorah's average, not your lot's — a low corner or a tree line moves it. Against Decorah's 191-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Decorah
Each reading below is measured for Decorah itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredDecorah runs about 191 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
MeasuredDecorah 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 Decorah is in
Decorah sits in the Driftless Area — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Decorah's own centroid rather than borrowed from Winneshiek County.
What Grows in Decorah
Every plant below cleared Decorah's own zone 5a and its 191-day season. Each card opens that plant's Iowa profile. How we score.
Is it too late to plant in Decorah?
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 17; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 14 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 22 — long-season crops need about 90 days of runway, quick greens only 30. Even past midsummer there is room for a true fall garden here, and garlic planted near the close carries the momentum into next year.
What's on the federal record near Decorah
Closest first, within ~10 miles of Decorah. Listing isn't leaking, and distance isn't exposure.
- THORNTON FEED & GRAINUnderground Storage Tanks · 300 ft
- PETER JOHNSON & SONSUnderground Storage Tanks · 300 ft
- DANS STANDARDUnderground Storage Tanks · 450 ft
- CONTINENTAL BAKING COUnderground Storage Tanks · 500 ft
- ERICH WEISSUnderground Storage Tanks · 750 ft
- COUNTRY STOREUnderground Storage Tanks · 750 ft
- STATE FISH MANAGEMENTUnderground Storage Tanks · 750 ft
- ROVERUD CONSTRUCTIONUnderground Storage Tanks · 750 ft
- FREEPORT COUNTRY STOREUnderground Storage Tanks · 750 ft
- FAUSER OIL CO INCUnderground Storage Tanks · 750 ft
- HESPER LOCKERUnderground Storage Tanks · 750 ft
- IDOTUnderground Storage Tanks · 750 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Decorah'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 Decorah.
Total Sites
146
within ~10 miles of Decorah
Risk Level
Moderate
Highest-severity
8 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Decorah
Severity Distribution
within ~10 miles of Decorah
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.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
Check your specific parcel in Decorah
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 Decorah average
Your land is one point inside Decorah
Everything above resolves to Decorah as a whole — one PHZM band and one 28°F frost record, read across 5K 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 Decorah Average
Decorah Average
- ●USDA Zones 5a, averaged across Decorah
- ●One soil character for all of Decorah
- ●Frost dates read at Decorah's scale: Apr 14 to Oct 22
YOUR Parcel
- ✓Your exact zone, not Decorah's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Decorah
Pull a site-specific report for your exact address in Decorah, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Decorah averages can't show:
We read public map data around Decorah — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Decorah average
How we know this about Decorah
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 Decorah’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 Decorah
When does frost risk typically end in Decorah?
The last hard freeze (28°F) in Decorah typically lands around Apr 14, 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 5.
When is the first frost in Decorah?
The first hard freeze (28°F) in Decorah typically arrives around Oct 22, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 8, so the watching starts about Sep 22 — about 191 days after the spring freeze cleared.
How long is the growing season in Decorah?
Measured between 28°F hard freezes, Decorah sees about 191 frost-free days — roughly Apr 14 through Oct 22, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 5 to Oct 8, about 156 days.
Is the soil safe to grow vegetables in Decorah?
The federal record around Decorah shows 146 documented sites, mostly Underground Storage Tanks entries (82), 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 Decorah?
From about Sep 22 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 22 (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 22. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Decorah's scale — its 5a band and its 191-day season. Your yard writes its own version of Decorah'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 Decorah’s own scale
6 of the readings below were taken at Decorah's own scale — its own ~191-day season between 28°F freezes, the 4,636 acres it covers and 146 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Decorah's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Decorah's own 28°F hard-freeze dates, about Apr 14 and Oct 22 and the ~191-day span between themNOAA 1991–2020 Climate Normals
- 146 documented contamination sites on the federal record near Decorah, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Decorah's boundary and the 4,636 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~191-day seasonGrowable Ground crop-matching engine
- The ecoregion at Decorah's own centroid, the Driftless AreaUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Decorah's 4,636 acres read through its county's SSURGO summaryfrom Winneshiek County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Winneshiek 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 Winneshiek County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Decorah's 4,636 acreswhy one lot differs from the next →
- Which side of Decorah you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 4,636 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 Decorah-wide figureread your own land →
More in Iowa
Growing region
Nearby growing guides