Otho, Iowa, sits in USDA hardiness zone 5a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
Well-matched crops include cabbage, cranberry, lavender, and collard greens, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
Even in Otho, 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 Otho 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 Otho — soil, climate, flood, and parcel records. How we handle your address.
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Otho — the short answer
Otho, Iowa: USDA zone 5a, about 190 days between hard freezes, across 284 acres of city.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 15
- 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
- ~190
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 284 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 Otho's average, not your lot's — a low corner or a tree line moves it. Against Otho's 190-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Otho
Each reading below is measured for Otho itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredOtho runs about 190 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
MeasuredOtho 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 Otho is in
Otho sits in the Western Corn Belt Plains — EPA Level III, inside the wider Great Plains. That is read at Otho's own centroid rather than borrowed from Webster County.
What Grows in Otho
Every plant below cleared Otho's own zone 5a and its 190-day season. Each card opens that plant's Iowa profile. How we score.
Is it too late to plant in Otho?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Mar 18; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 15 (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 Otho
Closest first, within ~10 miles of Otho. Listing isn't leaking, and distance isn't exposure.
- OTHO CONVENIENCE AND FOODUnderground Storage Tanks · 300 ft
- CENTRAL TELEPHONE COMPANYUnderground Storage Tanks · 700 ft
- 088N28W19ACBA 1978Otho 3Nitrate · 900 ft
- 088N28W19ACBA 07383 1955Otho 1Nitrate · 900 ft
- ROBERT EWINGUnderground Storage Tanks · 1000 ft
- 088N28W19BD 12698 1961Otho 2Nitrate · 2300 ft
- MIDAMERICAN ENERGY COMPANY LUNDGREN WIND FARMBrownfields · 1.7 mi
- 088N28W31BBA 01834 1943Nitrate · 1.8 mi
- 088N28W08DDB 03122 1946Nitrate · 1.8 mi
- 088N28W08DAD 07459 1955Coalville School DistrictNitrate · 1.9 mi
- COALVILLE STOP-N-SHOPUnderground Storage Tanks · 1.9 mi
- PEPSI-COLA BOTTLINGUnderground Storage Tanks · 1.9 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Otho'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 Otho.
Total Sites
387
within ~10 miles of Otho
Risk Level
Elevated
Highest-severity
2 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Otho
Severity Distribution
within ~10 miles of Otho
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Otho, Toxics Release Inventory runs higher than the national average — 28 sites within ~10 miles of Otho. 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.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Check your specific parcel in Otho
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 Otho average
Your land is one point inside Otho
Everything above resolves to Otho as a whole — one PHZM band and one 28°F frost record, read across 284 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 Otho Average
Otho Average
- ●USDA Zones 5a, averaged across Otho
- ●One soil character for all of Otho
- ●Frost dates read at Otho's scale: Apr 15 to Oct 22
YOUR Parcel
- ✓Your exact zone, not Otho's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Otho
Pull a site-specific report for your exact address in Otho, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Otho averages can't show:
We read public map data around Otho — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Otho average
How we know this about Otho
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 Otho’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 Otho
When does frost risk typically end in Otho?
The last hard freeze (28°F) in Otho typically lands around Apr 15, 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 6.
When is the first frost in Otho?
The first hard freeze (28°F) in Otho 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 190 days after the spring freeze cleared.
How long is the growing season in Otho?
Measured between 28°F hard freezes, Otho sees about 190 frost-free days — roughly Apr 15 through Oct 22, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 6 to Oct 8, about 155 days.
Is the soil safe to grow vegetables in Otho?
The federal record around Otho is a meaningful one — 387 documented sites, mostly Underground Storage Tanks entries (182), the nearest Underground Storage Tanks record under a tenth of a mile 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 Otho?
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 Otho's scale — its 5a band and its 190-day season. Your yard writes its own version of Otho'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 Otho’s own scale
6 of the readings below were taken at Otho's own scale — its own ~190-day season between 28°F freezes, the 284 acres it covers and 387 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Otho's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Otho's own 28°F hard-freeze dates, about Apr 15 and Oct 22 and the ~190-day span between themNOAA 1991–2020 Climate Normals
- 387 documented contamination sites on the federal record near Otho, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Otho's boundary and the 284 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~190-day seasonGrowable Ground crop-matching engine
- The ecoregion at Otho'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 Otho's 284 acres read through its county's SSURGO summaryfrom Webster County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Webster 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 Webster County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Otho's 284 acreswhy one lot differs from the next →
- Which side of Otho you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 284 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 Otho-wide figureread your own land →
More in Iowa
Wider growing context
What grows across IowaOtho sits outside our named growing regions, so Iowa as a whole is its closest context here.
Nearby growing guides