Audrain County, in Missouri, sits in USDA hardiness zone 6b — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
Well-matched crops include cabbage, hazelnut, lavender, and collard greens, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Audrain County holds more than one microclimate.
Soils and elevations shift across Audrain 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 Audrain County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Audrain County — the short answer
Audrain County, Missouri: USDA zone 6b, about 221 days between hard freezes, across 443K acres.
- USDA zone
- 6b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 29
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Nov 5
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~221
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 443K 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 6b is Audrain County's average, not your lot's — a low corner or a tree line moves it. Against Audrain County's 221-day season, see what your own ground reads.
Heat in Audrain County
Across a year, Audrain County accumulates about 3,630 growing degree days above 50°F, about 123 fewer than the middle Missouri county — ahead of 37 of Missouri’s 115 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 Audrain County
Across Audrain County, the ground is predominantly Alfisols, where Mexico, Leonard, and Armstrong are the most extensive named soil series. The soil is generally poorly drained with a silt loam surface. Topsoil pH runs about 6.5–6.8, neutral. Rainfall drains through hydrologic group D soils.
Soil order
Alfisols
Drainage
Poorly drained
Prime farmland
0%
Hydric soils
73%
Soil still varies lot by lot — soil types explained.
How the ground varies across Audrain County
The USDA soil survey maps 73% of Audrain County as poorly drained — but another 27% drains differently: 25% somewhat poorly drained, 1% moderately well drained.
Mexico is the most extensive named soil at 38% of mapped acres, then Leonard (16%) and Armstrong (12%).
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 Audrain County
Each reading below is measured for Audrain 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 Audrain County are poorly drained, in hydrologic group D — 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 Audrain County runs about pH 6.5–6.8, 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
MeasuredAudrain County runs about 221 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
MeasuredAudrain County sits in USDA hardiness zone 6b.
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 Audrain County is in
Audrain County sits in the Central Irregular Plains — EPA Level III, inside the wider Great Plains. One consistent ecological setting across the whole county.
What Grows in Audrain County
We scored all 1,086 plants against Audrain County's own USDA zone 6b and its own 221-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 Missouri profile.
Is it too late to plant in Audrain 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 1; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 29 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 5 — long-season crops need about 90 days of runway, quick greens only 30. With a season this long, “too late” mostly means “switch crops” — second sowings and a full fall garden are the norm, with garlic closing the year.
Documented around Audrain County
Survey cells within 31 miles of Audrain County checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 260 miles off. What to watch for.
- Japanese beetle1 documented records
- monarch butterfly1 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Audrain County
USGS estimates 178,309 lb of Atrazine on Audrain County farmland in 2019, its largest by weight, ahead of Glyphosate (143,844 lb) and Acetochlor (104,251 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 Audrain County — and how to grow with it.
We checked the federal record across Audrain County — 219 documented sites across 6 of the 9 source types we track.
The most significant on record: 17 Toxics Release Inventory facilities. Active industrial facilities reporting chemical releases to air, water, and land.
There's a meaningful federal record across Audrain 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 Audrain County
Closest first, across Audrain County. Listing isn't leaking, and distance isn't exposure.
- T51N R08W 08DDB1Nitrate · 1.1 mi
- NATIONAL REFRACTORIES & MINERALS INCToxics Release Inventory · 1.5 mi
- MCGEE PACKING COUnderground Storage Tanks · 2.2 mi
- MO AMERICAN MEXICOPFAS · 2.4 mi
- AZDELL HYDRAULICS & MACHINES INCBrownfields · 3.0 mi
- SHOP N GO NORTHUnderground Storage Tanks · 3.0 mi
- CASEYS GENERAL STORE #1377Underground Storage Tanks · 3.3 mi
- T51N R09W 26AAB1Nitrate · 3.3 mi
- AUDRAIN COUNTY HOSPITALBrownfields · 3.4 mi
- MEXICO FINAUnderground Storage Tanks · 3.4 mi
- XPRESS MARTUnderground Storage Tanks · 3.4 mi
- AUDRAIN MEDICAL CENTERUnderground Storage Tanks · 3.4 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Audrain 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 Audrain County.
Total Sites
219
across Audrain County
Risk Level
Elevated
Highest-severity
17 Toxics Release Inventory facilities
Sources Checked
across Audrain County
Severity Distribution
across Audrain County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Audrain County, two things run higher than the national average across Audrain County — CAFO (15 sites) and PFAS (3 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
CAFO: CAFOs pose a different contamination profile than chemical sources.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Check your specific parcel in Audrain 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 Audrain County average
Your land is one point inside Audrain County
Everything above resolves to Audrain County as a whole — one PHZM band and one county frost record, read across 443K 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 Audrain County Average
Audrain County Average
- ●USDA Zones 6b, averaged across Audrain County
- ●One soil character for all of Audrain County
- ●Frost dates read at Audrain County's scale: Mar 29 to Nov 5
YOUR Parcel
- ✓Your exact zone, not Audrain County's 6b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Audrain County
Pull a site-specific report for your exact address in Audrain County, Missouri — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Audrain County averages can't show:
We read public map data around Audrain County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Audrain County average
How we know this about Audrain 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 Audrain County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Audrain County
When does frost risk typically end in Audrain County?
The last hard freeze (28°F) in Audrain County typically lands around Mar 29, 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 19.
How long is the growing season in Audrain County?
Measured between 28°F hard freezes, Audrain County sees about 221 frost-free days — roughly Mar 29 through Nov 5, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 19 to Oct 22, about 186 days.
Is the soil safe to grow vegetables in Audrain County?
The federal record around Audrain County is a meaningful one — 219 documented sites, mostly Underground Storage Tanks entries (95), the nearest Nitrate record about 1.1 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 Audrain County's scale — its 6b band and its 221-day season. Your yard writes its own version of Audrain 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 Missouri's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Audrain County’s own scale
9 of the readings below were taken at Audrain County's own scale — its own ~221-day span between 28°F freezes, the 3 most extensive soil series mapped here and 219 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Audrain County's own USDA hardiness band, zones 6bUSDA PHZM 2023
- Audrain County's own 28°F hard-freeze dates and its ~221-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Audrain CountyUSDA NRCS SSURGO
- 219 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Nitrate record about 1.1 miles outFederal environmental registers
- Audrain County's boundary and the 443,039 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6b and a ~221-day seasonGrowable Ground crop-matching engine
- Audrain County sitting wholly inside the Central Irregular PlainsUS EPA Level III Ecoregions
- Open occurrence records documented in Audrain County for 2 tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Audrain County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Missouri grower plans around — written at state scale, so they stay on the state guidefrom Missouri
What this page can’t tell you
- How the season shifts across Audrain County — the ~221 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 Audrain County's 443,039 acreswhy one lot differs from the next →
- Which of those 219 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 Audrain Countyread your own land →