Worthington, 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.
On paper, cabbage, cranberry, lavender, and collard greens all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Even in Worthington, 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 Worthington 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 Worthington — soil, climate, flood, and parcel records. How we handle your address.
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Worthington — the short answer
Worthington, Iowa: USDA zone 5a, about 178 days between hard freezes, across 289 acres of city.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 18
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 13
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~178
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 289 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 Worthington's average, not your lot's — a low corner or a tree line moves it. Against Worthington's 178-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Worthington
Each reading below is measured for Worthington itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredWorthington runs about 178 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
MeasuredWorthington 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 Worthington is in
Worthington sits in the Western Corn Belt Plains — EPA Level III, inside the wider Great Plains. That is read at Worthington's own centroid, and it is not what its county reads: Dubuque County is mostly Driftless Area. The wider page above you is answering a different question about different ground.
What Grows in Worthington
Every plant below cleared Worthington's own zone 5a and its 178-day season. Each card opens that plant's Iowa profile. How we score.
Is it too late to plant in Worthington?
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 21; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 18 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 13 — long-season crops need about 90 days of runway, quick greens only 30. The tail of the season still works: sixty-day crops into late summer, quick greens after, garlic last of all.
What's on the federal record near Worthington
Closest first, within ~10 miles of Worthington. Listing isn't leaking, and distance isn't exposure.
- DAY BREAKUnderground Storage Tanks · 500 ft
- C & M HARDWAREUnderground Storage Tanks · 800 ft
- REITERS GARAGEUnderground Storage Tanks · 850 ft
- MORIARITY DXUnderground Storage Tanks · 950 ft
- J & L LUMBERUnderground Storage Tanks · 1100 ft
- HARRY SHADYUnderground Storage Tanks · 1100 ft
- 088N02W31ABAD 25996 1980WorthingtonNitrate · 1300 ft
- CITY OF WORTHINGTONUnderground Storage Tanks · 1300 ft
- L&S AG CENTERUnderground Storage Tanks · 1.0 mi
- Dyersville DiggingsMining · 2.5 mi
- 088N03W33DANitrate · 3.8 mi
- MIKE GRAVELUnderground Storage Tanks · 4.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Worthington'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 Worthington.
Total Sites
173
within ~10 miles of Worthington
Risk Level
Moderate
Highest-severity
14 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Worthington
Severity Distribution
within ~10 miles of Worthington
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Worthington, two things run higher than the national average within ~10 miles of Worthington — Toxics Release Inventory (14 sites) and Underground Storage Tanks (107 sites). 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.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Worthington
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 Worthington average
Your land is one point inside Worthington
Everything above resolves to Worthington as a whole — one PHZM band and one 28°F frost record, read across 289 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 Worthington Average
Worthington Average
- ●USDA Zones 5a, averaged across Worthington
- ●One soil character for all of Worthington
- ●Frost dates read at Worthington's scale: Apr 18 to Oct 13
YOUR Parcel
- ✓Your exact zone, not Worthington's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Worthington
Pull a site-specific report for your exact address in Worthington, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Worthington averages can't show:
We read public map data around Worthington — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Worthington average
How we know this about Worthington
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 Worthington’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 Worthington
When does frost risk typically end in Worthington?
The last hard freeze (28°F) in Worthington typically lands around Apr 18, 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 9.
When is the first frost in Worthington?
The first hard freeze (28°F) in Worthington typically arrives around Oct 13, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Sep 29, so the watching starts about Sep 13 — about 178 days after the spring freeze cleared.
How long is the growing season in Worthington?
Measured between 28°F hard freezes, Worthington sees about 178 frost-free days — roughly Apr 18 through Oct 13, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 9 to Sep 29, about 143 days.
Is the soil safe to grow vegetables in Worthington?
The federal record around Worthington shows 173 documented sites, mostly Underground Storage Tanks entries (107), 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 Worthington?
From about Sep 13 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 13 (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 13. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Worthington's scale — its 5a band and its 178-day season. Your yard writes its own version of Worthington'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 Worthington’s own scale
6 of the readings below were taken at Worthington's own scale — its own ~178-day season between 28°F freezes, the 289 acres it covers and 173 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Worthington's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Worthington's own 28°F hard-freeze dates, about Apr 18 and Oct 13 and the ~178-day span between themNOAA 1991–2020 Climate Normals
- 173 documented contamination sites on the federal record near Worthington, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Worthington's boundary and the 289 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~178-day seasonGrowable Ground crop-matching engine
- Worthington sits in the Western Corn Belt Plains — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Worthington's 289 acres read through its county's SSURGO summaryfrom Dubuque County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Dubuque 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 Dubuque County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Worthington's 289 acreswhy one lot differs from the next →
- Which side of Worthington you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 289 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 Worthington-wide figureread your own land →
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