Johnston County, in Oklahoma, sits in USDA hardiness zone 8a — a zone band wide enough that plant choice, not possibility, is the interesting question.
On paper, pecan, tomato, okra, and redbud 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
Johnston County holds more than one microclimate.
Soils and elevations shift across Johnston County, so your frost dates and drainage aren't the county average. Enter your address and we'll score 1,112 plants against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
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Quick Facts
USDA Zones
8a
Last Hard Freeze (28°F)
Feb 3
County normal — light frosts run a few weeks later
First Hard Freeze (28°F)
Dec 18
County normal — light frosts arrive a few weeks earlier
County Area
412K acres
Hardiness Zone Range
Zone maps are averages across Johnston County. Your yard's slope, trees, and frost pockets shift what actually grows — see your land's exact reading.
Soil in Johnston County
Across Johnston County, the ground is predominantly Alfisols, where Gasil, Chigley, and Claremore are the most extensive named soil series. The soil is generally well drained with a fine sandy loam surface. Topsoil pH runs about 5.9–6.7, slightly acidic. Rainfall drains through hydrologic group D soils.
Soil order
Alfisols
Drainage
Well drained
Prime farmland
43%
Hydric soils
0%
Soil still varies lot by lot — soil types explained.
What Grows in Johnston County
Plants matched to Johnston County's USDA zones 8a — each links to its full growing profile.
Is it too late to plant in Johnston County?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Jan 6; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 3 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 18 — long-season crops need about 90 days of runway, quick greens only 30. Here the calendar nearly circles: cool-season crops take the winter shift, and the next window is always close.
Growing Challenges in Oklahoma
What an experienced grower plans around here — each one has a move.
Extreme weather variability (tornadoes, ice storms, drought)
Flexible beats fortified here: row covers staged, storm-tough perennials, and quick-replant annual beds.
Red clay soils drain poorly in central OK
A raised bed ends the standing-water fight in a weekend, and fall compost keeps opening the clay below.
Low western rainfall requires irrigation
Western plots run on drip and mulch — plan the water before the planting and the dry years lose their teeth.
For cultivar selection, pest pressure, and planting-time guidance specific to Oklahoma, the Oklahoma State University Extension is the authoritative local source.
Safe to Grow Here?
What the federal record shows across Johnston County — and how to grow with it.
We checked the federal record across Johnston County — 115 documented sites across 7 of the 9 source types we track.
The most significant on record: 1 Superfund site. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
There's a meaningful federal record across Johnston 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.
Environmental Intelligence
Understanding what's nearby helps you make informed decisions about where and how to grow.
Sources Checked
across Johnston County
Severity Distribution
across Johnston County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Johnston County, two things run higher than the national average — CAFO (6 sites) and Nitrate (32 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.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Johnston County
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,112 plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Your Specific Parcel Matters
Johnston County Average
- ●USDA Zones 8a
- ●Generic soil type for the area
- ●State-average frost dates
YOUR Parcel
- ✓Your exact hardiness zone
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Johnston County
Pull a site-specific report for your exact address in Johnston County, Oklahoma — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Key Growing Facts for Johnston County, Oklahoma
- USDA Hardiness Zones: 8a (USDA PHZM 2023)
- Last Hard Freeze (28°F): Feb 3 (county normal, NOAA 1991–2020 Climate Normals — light frosts can follow for a few weeks)
- First Hard Freeze (28°F): Dec 18 (county normal, NOAA 1991–2020 Climate Normals — light frosts can arrive a few weeks earlier)
- Days Between Hard Freezes: ~318 (county normal, NOAA 1991–2020 Climate Normals)
- County Land Area: 412K acres (US Census TIGER 2025)
Zone data: USDA ARS Plant Hardiness Zone Map 2023. Climate data: NOAA NCEI. County boundaries: US Census TIGER/Line 2025.
Frost dates here are the Johnston County average. Low spots and tree cover move them by days on any one yard — see your exact frost windows.
Frequently Asked Questions
What hardiness zone is Johnston County, Oklahoma?
Johnston County sits in USDA hardiness zone 8a, per the USDA Plant Hardiness Zone Map 2023. Zones reflect average annual extreme minimum temperatures from 1991–2020 weather data.
Is it too late to plant in Johnston County?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Jan 6; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 3 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 18 — long-season crops need about 90 days of runway, quick greens only 30. Here the calendar nearly circles: cool-season crops take the winter shift, and the next window is always close.
When does frost risk typically end in Johnston County?
The last hard freeze (28°F) in Johnston County typically lands around Feb 3, per NOAA 1991–2020 climate normals — an earlier marker than the light-frost dates many planting charts quote. That marks the hard freeze, not the last light frost — light frosts can still bite for a few more weeks, so tender transplants usually wait another 2–3 weeks.
How long is the growing season in Johnston County?
Measured between 28°F hard freezes, Johnston County sees about 318 frost-free days — roughly Feb 3 through Dec 18, per NOAA 1991–2020 climate normals. Tender crops get a somewhat shorter practical window, since lighter frosts reach a few weeks past the hard-freeze dates on both ends.
What vegetables grow in Johnston County?
Johnston County's zone 8a supports a wide range — strong performers include Pecan, Tomato, Okra, Redbud, and Blackberry. What actually takes on any one site comes down to its soil, sun, and drainage, and we score each plant against the real conditions at your address.
Which hardiness zone is Johnston County, really?
Officially, Johnston County sits in USDA zone 8a (USDA PHZM 2023) — but a zone is a 30-year average of winter's coldest night across an area, and it can't see any one yard. A south-facing slope, a tree line, or a low frost pocket can shift a single site by half a zone either way, which is why neighboring gardeners often quote different numbers. We read the conditions at your exact address — soil, sun, slope, and frost — and score 1,112 plants against what's actually there.
Is the soil safe to grow vegetables in Johnston County?
The federal record around Johnston County is a meaningful one — 115 documented sites — 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.
Just moved to Johnston County — what should I know before planting?
Start with three facts. Johnston County sits in USDA zone 8a, which sets what survives winter; the last 28°F hard freeze typically clears around Feb 3, with about 318 frost-free days to work with (NOAA 1991–2020 climate normals); and 115 documented sites sit on the federal record here, so a soil test before food beds is the smart first step. From there, matching plants to your actual soil and sun is the fun part.
Everything on this page is a Johnston County average. Your yard writes its own version — 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.