Fort Madison, Iowa, sits in USDA hardiness zone 6a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
A short list that earns its place here — cabbage, blueberry, lavender, and collard greens — with any one site's soil, sun, and drainage making the final cut.
Even in Fort Madison, 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 Fort Madison 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 Fort Madison — soil, climate, flood, and parcel records. How we handle your address.
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Fort Madison — the short answer
Fort Madison, Iowa: USDA zone 6a, about 223 days between hard freezes, across 6K acres of city.
- USDA zone
- 6a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 30
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 8
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~223
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 6K 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 6a is Fort Madison's average, not your lot's — a low corner or a tree line moves it. Against Fort Madison's 223-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Fort Madison
Each reading below is measured for Fort Madison itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredFort Madison runs about 223 days between hard freezes — a long growing season.
There is slack for succession plantings and slow-finishing crops: many vegetables can be sown twice, and the heat-lovers have time to ripen fully.
Plan a second sowing of quick crops after the first comes out, and use the fall window most gardeners let sit idle.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredFort Madison sits in USDA hardiness zone 6a.
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 Fort Madison is in
Fort Madison sits in the Interior River Valleys and Hills — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Fort Madison's own centroid, and it is not what its county reads: Lee County is mostly Central Irregular Plains. The wider page above you is answering a different question about different ground.
What Grows in Fort Madison
Every plant below cleared Fort Madison's own zone 6a and its 223-day season. Each card opens that plant's Iowa profile. How we score.
Is it too late to plant in Fort Madison?
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 2; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 30 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 8 — long-season crops need about 90 days of runway, quick greens only 30. Here the season winds down slowly: late sowings, a real autumn harvest, and garlic in the ground before the first hard freeze.
What's on the federal record near Fort Madison
Closest first, within ~10 miles of Fort Madison. Listing isn't leaking, and distance isn't exposure.
- ANCHOR METALS INCToxics Release Inventory · 1000 ft
- Not KnownUnderground Storage Tanks · 1000 ft
- SINCLAIR #14010Underground Storage Tanks · 2000 ft
- FT MADISON READY MIXED CONCRETEUnderground Storage Tanks · 2100 ft
- HY-VEE GASUnderground Storage Tanks · 2100 ft
- RUANUnderground Storage Tanks · 2100 ft
- BJ PIPELINE CLEANERSBrownfields · 2200 ft
- B J PERFORMANCEUnderground Storage Tanks · 2400 ft
- B & M SERVICEBrownfields · 2400 ft
- ATCHISON TOPEKA & SANTA FE RRBrownfields · 2500 ft
- FORMER WINKE''S SERVICEUnderground Storage Tanks · 2500 ft
- MUNICIPAL BUILDINGUnderground Storage Tanks · 0.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Fort Madison'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 Fort Madison.
Sources Checked
within ~10 miles of Fort Madison
Severity Distribution
within ~10 miles of Fort Madison
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Fort Madison, two things run higher than the national average within ~10 miles of Fort Madison — Superfund (4 sites) and Toxics Release Inventory (19 sites). That's not a problem with your land — it's information about it.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Check your specific parcel in Fort Madison
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 Fort Madison average
Your land is one point inside Fort Madison
Everything above resolves to Fort Madison as a whole — one PHZM band and one 28°F frost record, read across 6K 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 Fort Madison Average
Fort Madison Average
- ●USDA Zones 6a, averaged across Fort Madison
- ●One soil character for all of Fort Madison
- ●Frost dates read at Fort Madison's scale: Mar 30 to Nov 8
YOUR Parcel
- ✓Your exact zone, not Fort Madison's 6a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Fort Madison
Pull a site-specific report for your exact address in Fort Madison, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Fort Madison averages can't show:
We read public map data around Fort Madison — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Fort Madison average
How we know this about Fort Madison
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 Fort Madison’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 Fort Madison
When does frost risk typically end in Fort Madison?
The last hard freeze (28°F) in Fort Madison typically lands around Mar 30, 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 Apr 20.
When is the first frost in Fort Madison?
The first hard freeze (28°F) in Fort Madison typically arrives around Nov 8, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 25, so the watching starts about Oct 9 — about 223 days after the spring freeze cleared.
How long is the growing season in Fort Madison?
Measured between 28°F hard freezes, Fort Madison sees about 223 frost-free days — roughly Mar 30 through Nov 8, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 20 to Oct 25, about 188 days.
Is the soil safe to grow vegetables in Fort Madison?
The federal record around Fort Madison is a meaningful one — 230 documented sites, mostly Underground Storage Tanks entries (98), the nearest Toxics Release Inventory record about 0.2 miles 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 Fort Madison?
From about Oct 9 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 Nov 8 (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 Nov 8. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Fort Madison's scale — its 6a band and its 223-day season. Your yard writes its own version of Fort Madison'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 Fort Madison’s own scale
6 of the readings below were taken at Fort Madison's own scale — its own ~223-day season between 28°F freezes, the 6,176 acres it covers and 230 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Fort Madison's own USDA hardiness band, zones 6aUSDA PHZM 2023
- Fort Madison's own 28°F hard-freeze dates, about Mar 30 and Nov 8 and the ~223-day span between themNOAA 1991–2020 Climate Normals
- 230 documented contamination sites on the federal record near Fort Madison, the closest Toxics Release Inventory record about 0.2 miles out from the town centreFederal environmental registers
- Fort Madison's boundary and the 6,176 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6a and a ~223-day seasonGrowable Ground crop-matching engine
- Fort Madison sits in the Interior River Valleys and Hills — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
Inherited from a wider read
- Soil character — no town-scale survey exists, so Fort Madison's 6,176 acres read through its county's SSURGO summaryfrom Lee County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Lee 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 Lee County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Fort Madison's 6,176 acreswhy one lot differs from the next →
- Which side of Fort Madison you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 6,176 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Toxics Release Inventory record about 0.2 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 Fort Madison-wide figureread your own land →