Louisa County, in Iowa, sits in USDA hardiness zone 5b — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Growers here do well with cabbage, blueberry, lavender, and collard greens — with the usual caveat that any single yard's soil, sun, and drainage cast the deciding vote.
Louisa County lies within the Southeast Iowa / Great River Region (Mississippi–Des Moines river corner) — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Louisa County holds more than one microclimate.
Soils and elevations shift across Louisa 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 Louisa County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Louisa County — the short answer
Louisa County, Iowa: USDA zone 5b, about 209 days between hard freezes, across 257K acres.
- USDA zone
- 5b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 5
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Oct 31
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~209
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 257K 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 Louisa County's average, not your lot's — a low corner or a tree line moves it. Against Louisa County's 209-day season, see what your own ground reads.
Heat in Louisa County
Across a year, Louisa County accumulates about 3,212 growing degree days above 50°F, about 468 more than the middle Iowa county — ahead of 94 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 Louisa County
Across Louisa County, the ground is predominantly Mollisols, where Clinton, Colo, and Mahaska are the most extensive named soil series. The soil is generally poorly drained with a silt loam surface. Topsoil pH runs about 6.2–6.5, slightly acidic. Rainfall drains through hydrologic group C soils.
Soil order
Mollisols
Drainage
Poorly drained
Prime farmland
35%
Hydric soils
29%
Soil still varies lot by lot — soil types explained.
How the ground varies across Louisa County
The USDA soil survey maps 27% of Louisa County as poorly drained — but another 69% drains differently: 22% moderately well drained, 20% somewhat poorly drained.
Clinton is the most extensive named soil at 8% of mapped acres, then Colo (5%) and Mahaska (5%).
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 Louisa County
Each reading below is measured for Louisa 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 Louisa County are poorly drained, in hydrologic group C — ground that sheds water slowly.
Beds can stay saturated for days after heavy rain, and the roots of most vegetables, berries, and fruit trees suffocate or rot in soil that never drains.
Raised beds or mounded rows lift roots above the wet zone; choose water-tolerant crops for the lowest spots.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Louisa 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
Season length
MeasuredLouisa County runs about 209 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
MeasuredLouisa County sits in USDA hardiness zone 5b.
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 Louisa County is in
Louisa County spans 2 EPA Level III ecoregions — Interior River Valleys and Hills (52%) and Western Corn Belt Plains (48%). 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 Louisa County
We scored all 1,086 plants against Louisa County's own USDA zone 5b and its own 209-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 Louisa County?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Mar 8; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 5 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Oct 31 — long-season crops need about 90 days of runway, quick greens only 30. A long window like this one runs successions deep into fall — and even its last weeks take quick greens and garlic.
Documented around Louisa County
- Japanese beetle1 documented records
- monarch butterfly12 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Louisa County
USGS estimates 134,279 lb of Glyphosate on Louisa County farmland in 2019, its largest by weight, ahead of Acetochlor (118,693 lb) and Atrazine (108,054 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 Louisa County — and how to grow with it.
We checked the federal record across Louisa County — 208 documented sites across 4 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 Louisa 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 Louisa County
Closest first, across Louisa County. Listing isn't leaking, and distance isn't exposure.
- 075N04W36DBC 1997NAWQA Louisa CountyNitrate · 2.4 mi
- 074N04W27BABB 11625 1959Nitrate · 3.1 mi
- FARMERS ELEVATOR & EXCHANGE INCUnderground Storage Tanks · 3.2 mi
- 074N03W32CBDNitrate · 3.8 mi
- CASEY''S GENERAL STORE 2498Underground Storage Tanks · 3.9 mi
- WHITE OAK STATION 80Underground Storage Tanks · 4.0 mi
- WAPELLO COMMUNITY SCHOOLSUnderground Storage Tanks · 4.0 mi
- 074N03W27CAA 58894Nitrate · 4.1 mi
- 074N04W20AAB Hutchinson NGPCNitrate · 4.1 mi
- FARMERS'' ELEVATOR FUEL SITEUnderground Storage Tanks · 4.2 mi
- 074N03W27BDDD 43030 1947Wapello 3Nitrate · 4.4 mi
- 074N03W27BDDD 43029 1976Wapello (3) 2Nitrate · 4.4 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Louisa 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 Louisa County.
Total Sites
208
across Louisa County
Risk Level
Elevated
Highest-severity
4 Toxics Release Inventory facilities
Sources Checked
across Louisa County
Severity Distribution
across Louisa County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Louisa County, Nitrate runs higher than the national average — 144 sites across Louisa County. 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.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Louisa 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 Louisa County average
Your land is one point inside Louisa County
Everything above resolves to Louisa County as a whole — one PHZM band and one county frost record, read across 257K 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 Louisa County Average
Louisa County Average
- ●USDA Zones 5b, averaged across Louisa County
- ●One soil character for all of Louisa County
- ●Frost dates read at Louisa County's scale: Apr 5 to Oct 31
YOUR Parcel
- ✓Your exact zone, not Louisa County's 5b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Louisa County
Pull a site-specific report for your exact address in Louisa County, Iowa — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Louisa County averages can't show:
We read public map data around Louisa County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Louisa County average
How we know this about Louisa 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 Louisa County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Louisa County
When does frost risk typically end in Louisa County?
The last hard freeze (28°F) in Louisa County typically lands around Apr 5, 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 26.
How long is the growing season in Louisa County?
Measured between 28°F hard freezes, Louisa County sees about 209 frost-free days — roughly Apr 5 through Oct 31, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 26 to Oct 17, about 174 days.
Is the soil safe to grow vegetables in Louisa County?
The federal record around Louisa County is a meaningful one — 208 documented sites, mostly Nitrate entries (144), the nearest Nitrate record about 2.4 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 Louisa County's scale — its 5b band and its 209-day season. Your yard writes its own version of Louisa 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 Louisa County’s own scale
9 of the readings below were taken at Louisa County's own scale — its own ~209-day span between 28°F freezes, the 3 most extensive soil series mapped here and 208 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Louisa County's own USDA hardiness band, zones 5bUSDA PHZM 2023
- Louisa County's own 28°F hard-freeze dates and its ~209-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Louisa CountyUSDA NRCS SSURGO
- 208 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Nitrate record about 2.4 miles outFederal environmental registers
- Louisa County's boundary and the 257,137 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 5b and a ~209-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Louisa County spans, Interior River Valleys and Hills the largestUS EPA Level III Ecoregions
- Open occurrence records documented in Louisa County for 2 tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Louisa 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 Louisa County — the ~209 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 Louisa County's 257,137 acreswhy one lot differs from the next →
- Which of those 208 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 Louisa Countyread your own land →