Harpers Ferry, 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.
The conditions favor cabbage, cranberry, lavender, and collard greens, among others — though every individual site edits that list with its own soil, sun, and drainage.
Even in Harpers Ferry, 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 Harpers Ferry 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 Harpers Ferry — soil, climate, flood, and parcel records. How we handle your address.
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Harpers Ferry — the short answer
Harpers Ferry, Iowa: USDA zone 5a, about 195 days between hard freezes, across 410 acres of city.
- USDA zone
- 5a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 11
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Oct 23
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~195
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 410 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 Harpers Ferry's average, not your lot's — a low corner or a tree line moves it. Against Harpers Ferry's 195-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Harpers Ferry
Each reading below is measured for Harpers Ferry itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredHarpers Ferry runs about 195 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
MeasuredHarpers Ferry 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 Harpers Ferry is in
Harpers Ferry sits in the Driftless Area — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Harpers Ferry's own centroid rather than borrowed from Allamakee County.
What Grows in Harpers Ferry
Every plant below cleared Harpers Ferry's own zone 5a and its 195-day season. Each card opens that plant's Iowa profile. How we score.
Is it too late to plant in Harpers Ferry?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Mar 14; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 11 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 23 — long-season crops need about 90 days of runway, quick greens only 30. Late in the year the fall bench takes over — quick greens, radishes, and garlic that repays you next summer.
What's on the federal record near Harpers Ferry
Closest first, within ~10 miles of Harpers Ferry. Listing isn't leaking, and distance isn't exposure.
- BARRY''S MINI-MARTUnderground Storage Tanks · 200 ft
- EFFIGY MOUNDS NATIONAL MONUMENTUnderground Storage Tanks · 1200 ft
- DEPT OF NATURAL RESOURCESUnderground Storage Tanks · 1200 ft
- DONAHUE''S ONE STOP LLCUnderground Storage Tanks · 1300 ft
- Harpers Ferry DiggingsMining · 2300 ft
- Mitchell's Liquor Box LLCUnderground Storage Tanks · 2.0 mi
- LYNXVILLE BAR & GROCERYUnderground Storage Tanks · 2.3 mi
- CR-08/06W/09-0153Nitrate · 3.5 mi
- CR-09/06W/27-0059Nitrate · 4.2 mi
- YELLOW RIVER STATE FORESTUnderground Storage Tanks · 4.8 mi
- YELLOW RIVER STATE FORESTBrownfields · 5.2 mi
- CRAWFORD COUNTY HWY DEPTUnderground Storage Tanks · 5.4 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Harpers Ferry'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 Harpers Ferry.
Total Sites
69
within ~10 miles of Harpers Ferry
Risk Level
Moderate
Highest-severity
5 Toxics Release Inventory facilities
Sources Checked
within ~10 miles of Harpers Ferry
Severity Distribution
within ~10 miles of Harpers Ferry
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Harpers Ferry, Toxics Release Inventory runs higher than the national average — 5 sites within ~10 miles of Harpers Ferry. That's not a problem with your land — it's information about it.
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 Harpers Ferry
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 Harpers Ferry average
Your land is one point inside Harpers Ferry
Everything above resolves to Harpers Ferry as a whole — one PHZM band and one 28°F frost record, read across 410 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 Harpers Ferry Average
Harpers Ferry Average
- ●USDA Zones 5a, averaged across Harpers Ferry
- ●One soil character for all of Harpers Ferry
- ●Frost dates read at Harpers Ferry's scale: Apr 11 to Oct 23
YOUR Parcel
- ✓Your exact zone, not Harpers Ferry's 5a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Harpers Ferry
Pull a site-specific report for your exact address in Harpers Ferry, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Harpers Ferry averages can't show:
We read public map data around Harpers Ferry — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Harpers Ferry average
How we know this about Harpers Ferry
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 Harpers Ferry’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 Harpers Ferry
When does frost risk typically end in Harpers Ferry?
The last hard freeze (28°F) in Harpers Ferry typically lands around Apr 11, 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 2.
When is the first frost in Harpers Ferry?
The first hard freeze (28°F) in Harpers Ferry typically arrives around Oct 23, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 9, so the watching starts about Sep 23 — about 195 days after the spring freeze cleared.
How long is the growing season in Harpers Ferry?
Measured between 28°F hard freezes, Harpers Ferry sees about 195 frost-free days — roughly Apr 11 through Oct 23, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 2 to Oct 9, about 160 days.
Is the soil safe to grow vegetables in Harpers Ferry?
The federal record around Harpers Ferry shows 69 documented sites, mostly Underground Storage Tanks entries (38), 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 Harpers Ferry?
From about Sep 23 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 23 (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 23. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Harpers Ferry's scale — its 5a band and its 195-day season. Your yard writes its own version of Harpers Ferry'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 Harpers Ferry’s own scale
6 of the readings below were taken at Harpers Ferry's own scale — its own ~195-day season between 28°F freezes, the 410 acres it covers and 69 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Harpers Ferry's own USDA hardiness band, zones 5aUSDA PHZM 2023
- Harpers Ferry's own 28°F hard-freeze dates, about Apr 11 and Oct 23 and the ~195-day span between themNOAA 1991–2020 Climate Normals
- 69 documented contamination sites on the federal record near Harpers Ferry, the closest Underground Storage Tanks record under a tenth of a mile out from the town centreFederal environmental registers
- Harpers Ferry's boundary and the 410 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5a and a ~195-day seasonGrowable Ground crop-matching engine
- The ecoregion at Harpers Ferry's own centroid, the Driftless AreaUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Harpers Ferry's 410 acres read through its county's SSURGO summaryfrom Allamakee County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Allamakee 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 Allamakee County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Harpers Ferry's 410 acreswhy one lot differs from the next →
- Which side of Harpers Ferry you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 410 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 Harpers Ferry-wide figureread your own land →
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