Adair County, in Oklahoma, sits in USDA hardiness zone 7a — a zone band wide enough that plant choice, not possibility, is the interesting question.
These conditions suit cabbage, hazelnut, california poppy, and collard greens — a starting list any specific site will trim or extend with its own soil, sun, and drainage.
Adair County lies within the Ozarks — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Adair County holds more than one microclimate.
Soils and elevations shift across Adair 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 Adair County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Adair County — the short answer
Adair County, Oklahoma: USDA zone 7a, about 231 days between hard freezes, across 367K acres.
- USDA zone
- 7a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Mar 24
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Nov 10
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~231
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 367K 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 7a is Adair County's average, not your lot's — a low corner or a tree line moves it. Against Adair County's 231-day season, see what your own ground reads.
Heat and winter chill in Adair County
Across a year, Adair County accumulates about 4,283 growing degree days above 50°F, about 437 fewer than the middle Oklahoma county — ahead of 5 of Oklahoma’s 77 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.
Winter banks about 2,036 hours below 45°F, 117 more than the Oklahoma middle of 1,919. Chill is what tells a fruit tree its dormancy is over, and it is set by climate rather than by anything you can build.
Grounded in PRISM Climate Group, Oregon State University — 1991–2020 monthly normals
Soil in Adair County
Across Adair County, the ground is predominantly Ultisols, where Clarksville, Enders, and Linker are the most extensive named soil series. The soil is generally somewhat excessively drained with a very stony silt loam surface. Topsoil pH runs about 4.4–5.8, strongly acidic. Rainfall drains through hydrologic group B soils.
Soil order
Ultisols
Drainage
Somewhat excessively drained
Prime farmland
21%
Hydric soils
0%
Soil still varies lot by lot — soil types explained.
How the ground varies across Adair County
The USDA soil survey maps 44% of Adair County as somewhat excessively drained — but another 56% drains differently: 43% well drained, 11% moderately well drained.
Clarksville is the most extensive named soil at 41% of mapped acres, then Enders (12%) and Linker (10%).
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 Adair County
Each reading below is measured for Adair 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 Adair County are somewhat excessively drained, in hydrologic group B — ground that drains quickly.
The upside is soil you can work early in spring and roots that never drown; the cost is that fast-draining ground dries out fast and leaches nutrients away before plants can use them.
Work in compost and mulch to hold moisture and feed, and water more often in short doses than deep and rarely.
USDA NRCS SSURGO
Surface pH
MeasuredTopsoil across Adair County runs about pH 4.4–5.8, on the acidic side.
Blueberries, potatoes, and rhododendrons thrive in it, but most vegetables start locking out nutrients below about pH 6.0 and grow pale and stunted no matter how much you feed them.
A measured lime application raises pH for the crops that need it — but test first, because the right rate depends on your own soil, not the county average.
USDA NRCS SSURGO
Season length
MeasuredAdair County runs about 231 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
MeasuredAdair County sits in USDA hardiness zone 7a.
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 Adair County is in
Adair County spans 2 EPA Level III ecoregions — Ozark Highlands (83%) and Boston Mountains (17%). 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 Adair County
We scored all 1,086 plants against Adair County's own USDA zone 7a and its own 231-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 Oklahoma profile.
Is it too late to plant in Adair County?
Rarely: the season closes in stages, not all at once, and each stage has its crops. Cool-season crops can go in from around Feb 24; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Mar 24 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 10 — long-season crops need about 90 days of runway, quick greens only 30. There is slack in a calendar like this — late plantings, second rounds of favorites, and a fall bench that keeps beds working.
What gets applied to farmland in Adair County
USGS estimates 12,116 lb of 2,4-d on Adair County farmland in 2019, its largest by weight, ahead of Triclopyr (4,362 lb) and Metolachlor & Metolachlor-s (843 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 Adair County — and how to grow with it.
We checked the federal record across Adair County — 93 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.
The federal record across Adair County is a modest one — a typical footprint for a growing area. Nothing here calls for alarm; it's worth knowing which recorded sites sit closest to where you grow, and each one on the map carries its type and location. If one turns out to be a near neighbor, a one-time soil test settles the question.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
What's on the federal record near Adair County
Closest first, across Adair County. Listing isn't leaking, and distance isn't exposure.
- GLENN D. YELLCAFO · 0.7 mi
- OK-AD-13Nitrate · 1.4 mi
- FACET FILTRATIONBrownfields · 2.4 mi
- O'REILLY AUTO PARTS STORE 2208Brownfields · 2.4 mi
- Sunshine #5Underground Storage Tanks · 2.7 mi
- Maryetta SchoolUnderground Storage Tanks · 4.0 mi
- Abandoned Country StoreUnderground Storage Tanks · 4.1 mi
- Ozarks Electric Cooperative CorUnderground Storage Tanks · 4.1 mi
- Okla Dept Of TransportationUnderground Storage Tanks · 4.2 mi
- Worley's (Ada Worley)Underground Storage Tanks · 4.4 mi
- Hop-In Food StoreUnderground Storage Tanks · 4.5 mi
- Christie SchoolUnderground Storage Tanks · 4.7 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Adair 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 Adair County.
Total Sites
93
across Adair County
Risk Level
Moderate
Highest-severity
4 Toxics Release Inventory facilities
Sources Checked
across Adair County
Severity Distribution
across Adair County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Adair County, two things run higher than the national average across Adair County — CAFO (9 sites) and Underground Storage Tanks (69 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.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Adair 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 Adair County average
Your land is one point inside Adair County
Everything above resolves to Adair County as a whole — one PHZM band and one county frost record, read across 367K 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 Adair County Average
Adair County Average
- ●USDA Zones 7a, averaged across Adair County
- ●One soil character for all of Adair County
- ●Frost dates read at Adair County's scale: Mar 24 to Nov 10
YOUR Parcel
- ✓Your exact zone, not Adair County's 7a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Adair County
Pull a site-specific report for your exact address in Adair County, Oklahoma — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Adair County averages can't show:
We read public map data around Adair County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Adair County average
How we know this about Adair 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 Adair County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Adair County
When does frost risk typically end in Adair County?
The last hard freeze (28°F) in Adair County typically lands around Mar 24, 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 14.
How long is the growing season in Adair County?
Measured between 28°F hard freezes, Adair County sees about 231 frost-free days — roughly Mar 24 through Nov 10, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 14 to Oct 27, about 196 days.
Is the soil safe to grow vegetables in Adair County?
The federal record around Adair County shows 93 documented sites, mostly Underground Storage Tanks entries (69), the nearest CAFO record about 0.7 miles 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.
Everything above is measured at Adair County's scale — its 7a band and its 231-day season. Your yard writes its own version of Adair 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 Oklahoma's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Adair County’s own scale
8 of the readings below were taken at Adair County's own scale — its own ~231-day span between 28°F freezes, the 3 most extensive soil series mapped here and 93 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Adair County's own USDA hardiness band, zones 7aUSDA PHZM 2023
- Adair County's own 28°F hard-freeze dates and its ~231-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Adair CountyUSDA NRCS SSURGO
- 93 documented contamination sites inside the county boundary, distance-sorted from its center — the closest CAFO record about 0.7 miles outFederal environmental registers
- Adair County's boundary and the 367,284 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 7a and a ~231-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Adair County spans, Ozark Highlands the largestUS EPA Level III Ecoregions
- Which agricultural compounds go onto Adair County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Oklahoma grower plans around — written at state scale, so they stay on the state guidefrom Oklahoma
What this page can’t tell you
- How the season shifts across Adair County — the ~231 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 Adair County's 367,284 acreswhy one lot differs from the next →
- Which of those 93 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 Adair Countyread your own land →