Warren County, in Iowa, sits in USDA hardiness zone 5b — a zone band wide enough that plant choice, not possibility, is the interesting question.
On paper, cabbage, cranberry, lavender, and collard greens all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Warren County holds more than one microclimate.
Soils and elevations shift across Warren County, so your frost dates and drainage aren't the county average. 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 Warren County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Warren County — the short answer
Warren County, Iowa: USDA zone 5b, about 196 days between hard freezes, across 365K acres.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 10
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 23
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~196
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 365K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are county 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 5b is Warren County's average, not your lot's — a low corner or a tree line moves it. Against Warren County's 196-day season, see what your own ground reads.
Heat in Warren County
Across a year, Warren County accumulates about 3,052 growing degree days above 50°F, about 308 more than the middle Iowa county — ahead of 84 of Iowa’s 99 counties. Degree days are the heat a crop actually gets to work with — more of them is more room to ripen a long-season crop before the freeze closes the window.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in Warren County
Across Warren County, the ground is predominantly Alfisols, where Ladoga, Gara, and Sharpsburg are the most extensive named soil series. The soil is generally moderately well drained with a silty clay loam surface. Topsoil pH runs about 6.2–6.5, slightly acidic. Rainfall drains through hydrologic group C soils.
Soil order
Alfisols
Drainage
Moderately well drained
Prime farmland
24%
Hydric soils
20%
Soil still varies lot by lot — soil types explained.
How the ground varies across Warren County
The USDA soil survey maps 33% of Warren County as moderately well drained — but another 66% drains differently: 27% somewhat poorly drained, 19% well drained.
Ladoga is the most extensive named soil at 10% of mapped acres, then Gara (8%) and Sharpsburg (7%).
Which of them your own lot sits on is a parcel question, not a county one. Check your address for the survey at your boundary.
What this means for growing in Warren County
Each reading below is measured for Warren County itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Drainage
MeasuredThe dominant soils across Warren County are moderately well drained, in hydrologic group C — roughly the middle of the drainage range.
This is close to the middle most vegetables prefer: it holds enough water to carry a crop between rains without staying waterlogged. The catch is that a wet spring or a low corner can still tip it soggy.
Plant on the site as-is for most crops, but keep the lowest, slowest-draining beds for moisture-tolerant plantings.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Warren County runs about pH 6.2–6.5, close to neutral.
This is the range most vegetables prefer — one correction you probably do not have to make, which is genuinely good news for a new bed.
Keep it there with compost rather than lime or sulfur, and only amend if your own soil test says otherwise.
USDA NRCS SSURGO
Wet ground
MeasuredAbout 20% of Warren County is mapped as hydric — wetland — soil.
If your lot falls in one of those pockets, a standard in-ground bed will fight waterlogging all season, and roots that need air will struggle.
Check how your own ground drains before you dig; raised beds or moisture-loving plantings turn a wet corner from a problem into a niche.
USDA NRCS SSURGO
Season length
MeasuredWarren County runs about 196 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
The kind of country Warren County is in
Warren County spans 2 EPA Level III ecoregions — Western Corn Belt Plains (82%) and Central Irregular Plains (18%). Which one your land falls in changes what grows wild there and how the ground behaves, and a county-wide answer cannot tell you which.
What Grows in Warren County
We scored all 1,086 plants against Warren County's own USDA zone 5b and its own 196-day season between hard freezes, using the same matching engine that runs a full parcel report. These cleared both. Sun, soil pH and drainage vary lot by lot — those are the parcel questions below. Each card opens that plant's Iowa profile.
Is it too late to plant in Warren County?
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 13; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 10 (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. The tail of the season still works: sixty-day crops into late summer, quick greens after, garlic last of all.
Documented around Warren County
- monarch butterfly57 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Warren County
USGS estimates 97,182 lb of Glyphosate on Warren County farmland in 2019, its largest by weight, ahead of Metolachlor & Metolachlor-s (52,639 lb) and Atrazine (44,670 lb).
Farmland across the whole county, not any one lot. Check your address for the site-by-site record.
Safe to Grow Here?
What the federal record shows across Warren County — and how to grow with it.
We checked the federal record across Warren County — 313 documented sites across 5 of the 9 source types we track.
The most significant on record: 4 Toxics Release Inventory facilities. Active industrial facilities reporting chemical releases to air, water, and land.
There's a meaningful federal record across Warren County — worth a look before you plant food, not a reason to hold back from growing. Proximity to a documented site is information, not a diagnosis of any one yard. A soil test before new food beds is the sensible precaution here, and the map shows exactly which sites sit where, so you can see what's actually near you.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Warren County
Closest first, across Warren County. Listing isn't leaking, and distance isn't exposure.
- 075N24W01BABD 1939IndianolaNitrate · 850 ft
- 076N24W36CCB 1916Indianola 1Nitrate · 0.6 mi
- 076N24W36CAC 1920Indianola 2Nitrate · 0.6 mi
- 076N24W36CBC 06995 1955Indianola 9Nitrate · 0.6 mi
- 075N23W06BCD 1967Nitrate · 0.8 mi
- INDIANOLA WATER SUPPLYPFAS · 0.8 mi
- I O O F CEMETERYUnderground Storage Tanks · 1.2 mi
- 076N23W31DADD 23702 1976Indianola 11Nitrate · 1.6 mi
- INDIANOLA HOG MKT INCUnderground Storage Tanks · 1.6 mi
- CASEY''S GENERAL STORE 1908Underground Storage Tanks · 1.7 mi
- BORCHERTS 66 SERVICEUnderground Storage Tanks · 1.8 mi
- CASEY''S GENERAL STORE 2097Underground Storage Tanks · 1.8 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Warren County'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 Warren County.
Total Sites
313
across Warren County
Risk Level
Elevated
Highest-severity
4 Toxics Release Inventory facilities
Sources Checked
across Warren County
Severity Distribution
across Warren County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Warren County, two things run higher than the national average across Warren County — Nitrate (136 sites) and PFAS (3 sites). That's not a problem with your land — it's information about it.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Check your specific parcel in Warren County
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 Warren County average
Your land is one point inside Warren County
Everything above resolves to Warren County as a whole — one PHZM band and one county frost record, read across 365K 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 county 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 county average.
Your Lot vs the Warren County Average
Warren County Average
- ●USDA Zones 5b, averaged across Warren County
- ●One soil character for all of Warren County
- ●Frost dates read at Warren County's scale: Apr 10 to Oct 23
YOUR Parcel
- ✓Your exact zone, not Warren County's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Warren County
Pull a site-specific report for your exact address in Warren County, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Warren County averages can't show:
We read public map data around Warren County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Warren County average
How we know this about Warren County
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at county grain; hard-freeze dates from NOAA 1991–2020 28°F normals at this county’s own record where one resolves, and the labelled statewide window where none does; soils from the USDA NRCS SSURGO survey, area-weighted across the county’s own map units; boundaries and acreage from US Census TIGER/Line 2025; the contamination and pesticide records from the federal sources named in their beats above. Where Warren County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Warren County
When does frost risk typically end in Warren County?
The last hard freeze (28°F) in Warren County typically lands around Apr 10, 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 1.
How long is the growing season in Warren County?
Measured between 28°F hard freezes, Warren County sees about 196 frost-free days — roughly Apr 10 through Oct 23, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer May 1 to Oct 9, about 161 days.
Is the soil safe to grow vegetables in Warren County?
The federal record around Warren County is a meaningful one — 313 documented sites, mostly Nitrate entries (136), the nearest Nitrate 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.
Everything above is measured at Warren County's scale — its 5b band and its 196-day season. Your yard writes its own version of Warren County's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Iowa's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Warren County’s own scale
9 of the readings below were taken at Warren County's own scale — its own ~196-day span between 28°F freezes, the 3 most extensive soil series mapped here and 313 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Warren County's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Warren County's own 28°F hard-freeze dates and its ~196-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Warren CountyUSDA NRCS SSURGO
- 313 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Nitrate record about 0.2 miles outFederal environmental registers
- Warren County's boundary and the 364,581 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~196-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Warren County spans, Western Corn Belt Plains the largestUS EPA Level III Ecoregions
- Open occurrence records documented in Warren County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Warren County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Iowa grower plans around — written at state scale, so they stay on the state guidefrom Iowa
What this page can’t tell you
- How the season shifts across Warren County — the ~196 days above is one reading at its centre; the 12 towns below each carry their owntowns in this county →
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Warren County's 364,581 acreswhy one lot differs from the next →
- Which of those 313 documented sites actually reaches your soil — that needs your address, the wind, and the groundwater directionhow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — none of it survives being averaged over Warren Countyread your own land →