Charles City, Iowa, sits in USDA hardiness zone 5a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
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 Charles City, 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 Charles City 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 Charles City — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Charles City — the short answer
Charles City, Iowa: USDA zone 5a, about 191 days between hard freezes, across 4K acres of city.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 12
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 20
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~191
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 4K 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 Charles City's average, not your lot's — a low corner or a tree line moves it. Against Charles City's 191-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Charles City
Each reading below is measured for Charles City itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredCharles City 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
MeasuredCharles City 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 Charles City is in
Charles City sits in the Western Corn Belt Plains — EPA Level III, inside the wider Great Plains. That is read at Charles City's own centroid rather than borrowed from Floyd County.
What Grows in Charles City
Every plant below cleared Charles City'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 Charles City?
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 15; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 12 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 20 — 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 Charles City
Closest first, within ~10 miles of Charles City. Listing isn't leaking, and distance isn't exposure.
- HY-VEE GASUnderground Storage Tanks · 550 ft
- E & N TIRE INCUnderground Storage Tanks · 700 ft
- CASEY''S GENERAL STORE 2480Underground Storage Tanks · 800 ft
- BUY LOW SELF SERVEUnderground Storage Tanks · 850 ft
- LEON & GENES INCUnderground Storage Tanks · 1100 ft
- DIAMOND TRANSPORTUnderground Storage Tanks · 1200 ft
- SALSBURY LABORATORIES INCUnderground Storage Tanks · 1200 ft
- FLOYD COUNTY MEMORIAL HOSPITALUnderground Storage Tanks · 1200 ft
- BISSONNETTE CHEV INCUnderground Storage Tanks · 1300 ft
- 095N16W12ADC 00020 1928Charles City 3Nitrate · 1400 ft
- 095N16W12ABA 00114 1906Charles City 1Nitrate · 1400 ft
- EXPRESS LUBEUnderground Storage Tanks · 1400 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Charles City'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 Charles City.
Sources Checked
within ~10 miles of Charles City
Severity Distribution
within ~10 miles of Charles City
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Charles City, two things run higher than the national average within ~10 miles of Charles City — Superfund (3 sites) and Nitrate (36 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Charles City
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 Charles City average
Your land is one point inside Charles City
Everything above resolves to Charles City as a whole — one PHZM band and one 28°F frost record, read across 4K 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 Charles City Average
Charles City Average
- ●USDA Zones 5a, averaged across Charles City
- ●One soil character for all of Charles City
- ●Frost dates read at Charles City's scale: Apr 12 to Oct 20
YOUR Parcel
- ✓Your exact zone, not Charles City's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Charles City
Pull a site-specific report for your exact address in Charles City, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Charles City averages can't show:
We read public map data around Charles City — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Charles City average
How we know this about Charles City
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 Charles City’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 Charles City
When does frost risk typically end in Charles City?
The last hard freeze (28°F) in Charles City typically lands around Apr 12, 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 3.
When is the first frost in Charles City?
The first hard freeze (28°F) in Charles City typically arrives around Oct 20, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 6, so the watching starts about Sep 20 — about 191 days after the spring freeze cleared.
How long is the growing season in Charles City?
Measured between 28°F hard freezes, Charles City sees about 191 frost-free days — roughly Apr 12 through Oct 20, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 3 to Oct 6, about 156 days.
Is the soil safe to grow vegetables in Charles City?
The federal record around Charles City runs heavier than most — 139 documented sites, mostly Underground Storage Tanks entries (69), the nearest Underground Storage Tanks record about 0.1 miles out — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
How do I protect my plants from frost in Charles City?
From about Sep 20 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 20 (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 20. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Charles City's scale — its 5a band and its 191-day season. Your yard writes its own version of Charles City'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 Charles City’s own scale
6 of the readings below were taken at Charles City's own scale — its own ~191-day season between 28°F freezes, the 3,919 acres it covers and 139 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Charles City's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Charles City's own 28°F hard-freeze dates, about Apr 12 and Oct 20 and the ~191-day span between themNOAA 1991–2020 Climate Normals
- 139 documented contamination sites on the federal record near Charles City, the closest Underground Storage Tanks record about 0.1 miles out from the town centreFederal environmental registers
- Charles City's boundary and the 3,919 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 Charles City'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 Charles City's 3,919 acres read through its county's SSURGO summaryfrom Floyd County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Floyd 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 Floyd County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Charles City's 3,919 acreswhy one lot differs from the next →
- Which side of Charles City you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 3,919 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 Charles City-wide figureread your own land →
More in Iowa
Wider growing context
What grows across IowaCharles City sits outside our named growing regions, so Iowa as a whole is its closest context here.