Clarksville, 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.
Reliable performers under these conditions include cabbage, cranberry, lavender, and collard greens; what your own ground favors still comes down to its soil, sun, and drainage.
Even in Clarksville, 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 Clarksville 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 Clarksville — soil, climate, flood, and parcel records. How we handle your address.
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Clarksville — the short answer
Clarksville, Iowa: USDA zone 5a, about 189 days between hard freezes, across 838 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 20
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~189
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 838 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 Clarksville's average, not your lot's — a low corner or a tree line moves it. Against Clarksville's 189-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Clarksville
Each reading below is measured for Clarksville itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredClarksville runs about 189 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
MeasuredClarksville 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 Clarksville is in
Clarksville sits in the Western Corn Belt Plains — EPA Level III, inside the wider Great Plains. That is read at Clarksville's own centroid rather than borrowed from Butler County.
What Grows in Clarksville
Every plant below cleared Clarksville's own zone 5a and its 189-day season. Each card opens that plant's Iowa profile. How we score.
Is it too late to plant in Clarksville?
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 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 20 — long-season crops need about 90 days of runway, quick greens only 30. As the window narrows, the plantings just get faster — fall brassicas, then greens, then garlic to finish.
What's on the federal record near Clarksville
Closest first, within ~10 miles of Clarksville. Listing isn't leaking, and distance isn't exposure.
- CLARKSVILLE FERTILIZERUnderground Storage Tanks · 450 ft
- WILKEN WELDINGBrownfields · 900 ft
- BACKERS SERVICE STATIONUnderground Storage Tanks · 1200 ft
- PACKARD ELEVATORUnderground Storage Tanks · 1400 ft
- BUTLER COUNTY ENGINEERUnderground Storage Tanks · 1400 ft
- CASEY''S GENERAL STORE 2680Underground Storage Tanks · 1500 ft
- MIDAMERICAN ENERGY COMPANY CLARKSVILLE SERVICE CENTERBrownfields · 1600 ft
- JERRYS REPAIR AND SERVICEUnderground Storage Tanks · 1700 ft
- ERIC WEDEKING AUTO BODYBrownfields · 1900 ft
- 092N15W18BCAA 1938Clarksville 1 NorthNitrate · 1900 ft
- 092N15W18BCAA 26455 1981Clarksville 3Nitrate · 1900 ft
- 092N15W18BCAA 1939Clarksville 2 SouthNitrate · 1900 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Clarksville'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 Clarksville.
Total Sites
123
within ~10 miles of Clarksville
Risk Level
Moderate
Highest-severity
8 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Clarksville
Severity Distribution
within ~10 miles of Clarksville
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Clarksville, two things run higher than the national average within ~10 miles of Clarksville — Nitrate (34 sites) and Toxics Release Inventory (8 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Check your specific parcel in Clarksville
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 Clarksville average
Your land is one point inside Clarksville
Everything above resolves to Clarksville as a whole — one PHZM band and one 28°F frost record, read across 838 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 Clarksville Average
Clarksville Average
- ●USDA Zones 5a, averaged across Clarksville
- ●One soil character for all of Clarksville
- ●Frost dates read at Clarksville's scale: Apr 14 to Oct 20
YOUR Parcel
- ✓Your exact zone, not Clarksville's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Clarksville
Pull a site-specific report for your exact address in Clarksville, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Clarksville averages can't show:
We read public map data around Clarksville — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Clarksville average
How we know this about Clarksville
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 Clarksville’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 Clarksville
When does frost risk typically end in Clarksville?
The last hard freeze (28°F) in Clarksville 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 Clarksville?
The first hard freeze (28°F) in Clarksville 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 189 days after the spring freeze cleared.
How long is the growing season in Clarksville?
Measured between 28°F hard freezes, Clarksville sees about 189 frost-free days — roughly Apr 14 through Oct 20, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 5 to Oct 6, about 154 days.
Is the soil safe to grow vegetables in Clarksville?
The federal record around Clarksville shows 123 documented sites, mostly Underground Storage Tanks entries (55), 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 Clarksville?
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 Clarksville's scale — its 5a band and its 189-day season. Your yard writes its own version of Clarksville'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 Clarksville’s own scale
6 of the readings below were taken at Clarksville's own scale — its own ~189-day season between 28°F freezes, the 838 acres it covers and 123 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Clarksville's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Clarksville's own 28°F hard-freeze dates, about Apr 14 and Oct 20 and the ~189-day span between themNOAA 1991–2020 Climate Normals
- 123 documented contamination sites on the federal record near Clarksville, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Clarksville's boundary and the 838 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~189-day seasonGrowable Ground crop-matching engine
- The ecoregion at Clarksville'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 Clarksville's 838 acres read through its county's SSURGO summaryfrom Butler County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Butler 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 Butler County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Clarksville's 838 acreswhy one lot differs from the next →
- Which side of Clarksville you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 838 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 Clarksville-wide figureread your own land →
More in Iowa
Wider growing context
What grows across IowaClarksville sits outside our named growing regions, so Iowa as a whole is its closest context here.
Nearby growing guides