The Ouachita Mountains spans USDA hardiness zones 7b-8a — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
Arkansas's Ouachita Mountains run in long east-west acidic rock ridges and cool hollows — an Interior Highlands division of thin cherty soil and steep slope aspect, unlike any flat ground in the state. The higher western counties hold zone 7b-8a and a shorter frost-free window (Montgomery ~232 days, Polk ~245) than the 8a bottomlands, so hill gardening here is a slope, aspect, and drainage story the state's 8a/254 median can't tell. On paper, tomato, sweet potato, peach, and muscadine grape all suit these conditions — on the ground, soil, sun, and drainage make the final call.
The Ouachita Mountains spans Arkansas.
Your yard isn't all of the Ouachita Mountains.
The Ouachita Mountains spans USDA zones 7b-8a, but your parcel sits in exactly one — and slope, tree cover, and low spots nudge it further. 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 Ouachita Mountains — soil, climate, flood, and parcel records. How we handle your address.
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The Ouachita Mountains — the short answer
The Ouachita Mountains: USDA zones 7b-8a, 232–266 frost-free days depending where in it you stand, in Arkansas.
- USDA zones
- 7b-8a
- USDA PHZM 2023, aggregated over the footprint
- Shortest season here
- 232 days
- NOAA Regional Climate Centers ACIS, 1991-2020 — Montgomery County
- Counties
- 9
- US Census TIGER/Line 2025
- Region type
- County cluster
- Growable Ground growing-region registry
Region boundary: Growable Ground growing-region registry — curated county clusters, EPA Level III ecoregions, and town clusters drawn finer than any county. The season figure is this region's own record, measured across its 9 member counties, not a state or national average.
Hardiness Zone Range
The Ouachita Mountains is not one growing season
One answer for the Ouachita Mountains averages 9 counties whose growing seasons are 34 days apart — from 232 frost-free days in Montgomery County to 266 in Saline County. That is the same region, measured the same way, in the same years. Which end of it your land sits nearer decides what finishes before the first hard freeze.
The middle half of 9 counties runs 237–247 days, with a median of 245 days — a 34-day span end to end.
Measured across 9 member counties, each carrying its own 28°F normal. NOAA Regional Climate Centers ACIS, 1991-2020. A member with no own record is absent from the range rather than counted as zero — nothing here is interpolated to the region. Your own site sits somewhere inside this range; a parcel report resolves where.
Where the line runs inside the Ouachita Mountains
The middle half of the Ouachita Mountains runs 237–247 frost-free days, and 4 of its 9 counties sit outside that — 2 on the short side, 2 on the long. A regional planting date describes the middle well and the ends poorly, which is worth knowing before you follow one.
Under 237 frost-free days
2 counties
- Montgomery County · 232 days
- Pike County · 235 days
The end of the region that sets the planting calendar — start seed indoors here and the season stretches to meet the crop.
237–247 frost-free days
5 counties
0 of 5 shown
The middle half of the region, and the part a single regional season describes well.
Over 247 frost-free days
2 counties
- Saline County · 266 days
- Hot Spring County · 261 days
Long enough for a second succession of a quick crop after the first comes out.
Each county is placed by its OWN 28°F frost-free normal (NOAA Regional Climate Centers ACIS, 1991-2020), the same figure its own guide page publishes. Elevation, slope and cold-air drainage move a site within its county as well — which is the part only your address resolves.
What Grows in the Ouachita Mountains
All 2 of the plants below that publish a season requirement clear even Montgomery County’s 232 frost-free days — so on season alone, this grid works at both ends of the region. The 34-day spread still decides how far past this list you can push, and how early you can start.
Plants matched to the Ouachita Mountains' USDA zones 7b-8a, ordered by how much hardiness margin each has across the region — the ones with room to spare at both ends of this band lead. Each links to its full growing profile.
Native Plants of the Ouachita Mountains
Plants the USDA PLANTS Database documents as native and present in this region’s state, kept only where the published hardiness range meets the Ouachita Mountains’s USDA zones 7b-8a — closest range match first. Presence is recorded by state, so a plant can be documented across the state and still be scarce in your corner of the region.
The ground across the Ouachita Mountains
The USDA soil survey maps this ground county by county. These are those records weighted by land area across nine member counties — this region’s own profile, not a state figure.
The ground is predominantly Ultisols, at 72% of mapped acres, followed by Inceptisols (14%), Alfisols (10%) and Entisols (4%). Six soil orders appear somewhere inside the footprint, which is the honest reason a regional soil answer only goes so far. The most extensive named soils are Carnasaw, Sherless, and Bismarck.
74% of those acres are well drained, and another 12% moderately well drained, 5% somewhat excessively drained. Topsoil pH runs 5.0–5.8 between the lowest and the highest county on record. 12% of the footprint is classed prime farmland.
Soil order
Ultisols
Drainage
Well drained
Topsoil pH
5.0–5.8
Hydric soils
3%
Soil changes across a driveway, so which of these your own ground sits on is a parcel question rather than a regional one. Saline County holds the most wetland ground here, at 10% — soil types explained.
USDA NRCS SSURGO via Soil Data Access
What this means for growing in the Ouachita Mountains
The soil survey reads this ground county by county, and the readings above are those records summed across the Ouachita Mountains. Here is what they mean for a garden here — and the move an experienced grower makes about each one.
Drainage
From county records74% of the mapped acres across the Ouachita Mountains are well drained — ground that drains quickly. That is area-weighted across all nine of its mapped counties.
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
From county recordsTopsoil across the Ouachita Mountains runs pH 5.0–5.8 — acidic in all nine of them.
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
Safe to Grow Here?
What the federal record shows across the Ouachita Mountains — and how to grow with it.
Across the Ouachita Mountains' 9 counties the federal record holds 1,893 documented sites, mostly Underground Storage Tanks (1,096), Nitrate (386) and Brownfields (240). The heaviest single county is Garland County, with 439.
That is a regional count, not a reading of any one lot — proximity to a documented site is information, not a diagnosis. Open the map outlined to the Ouachita Mountains to see which records sit where you actually grow.
Sources Checked
Summed across the 9 counties in the Ouachita Mountains
Know Before You Grow
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
- •On a private well, test for nitrates: above 10 mg/L the water needs treatment before irrigating.
- •Near a brownfield, raised beds of imported soil give your food clean ground.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Your land is one point inside the Ouachita Mountains
Everything above resolves to the Ouachita Mountains as a whole — a footprint whose own counties record seasons 34 days apart, and hardiness across zones 7b-8a. Your parcel sits at one point in that range, not in the middle of it. 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 region 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 regional average.
Your Lot vs the Ouachita Mountains Average
Ouachita Mountains Average
- ●USDA Zones 7b-8a, averaged across Ouachita Mountains
- ●One soil character for all of Ouachita Mountains
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not Ouachita Mountains' 7b-8a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in the Ouachita Mountains
Pull a site-specific report for your exact address in the Ouachita Mountains — soil, sun, drainage, frost risk, contamination, and scored plant recommendations.
Three things about your lot that Ouachita Mountains averages can't show:
We read public map data around The Ouachita Mountains — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Ouachita Mountains average
How we know this about the Ouachita Mountains
The boundary: a cluster of neighboring counties. Growing regions have no official boundary, so this footprint is our published one, and every figure on this page was measured over the counties inside it rather than borrowed from the state around it.
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, aggregated across the footprint; the growing season from NOAA Regional Climate Centers ACIS 1991–2020 28°F normals, read at each member’s own record; boundaries from US Census TIGER/Line 2025; the contamination record from the federal sources named in that beat above; the soil from the USDA NRCS SSURGO survey, read at each member county’s own record and weighted to this footprint by land area. Where a member carries no record of its own, it is absent from the figure rather than filled in.
Common questions about the Ouachita Mountains
What hardiness zone is the Ouachita Mountains?
The Ouachita Mountains spans USDA hardiness zones 7b-8a, aggregated from the USDA Agricultural Research Service Plant Hardiness Zone Map 2023 across the region's counties. Zones reflect average annual extreme minimum temperatures from 1991–2020 data.
How long is the growing season in the Ouachita Mountains?
Measured between 28°F hard freezes, the Ouachita Mountains' counties mostly run 237 to 247 frost-free days, median 245 (NOAA Regional Climate Centers ACIS, 1991–2020, over 9 member counties). That 10-day spread is the honest read — no single season describes 9 counties, and each county guide below carries its own.
When does frost risk end in the Ouachita Mountains?
Across the Ouachita Mountains, the middle half of member counties see their last 28°F hard freeze between Mar 13 and Mar 21 (median Mar 15), and their first fall freeze between Nov 13 and Nov 17. Those are hard freezes, not the last light frost: tender transplants wait for about Apr 5, and elevation decides which end of a 8-day spread you garden in.
What grows well in the Ouachita Mountains?
The Ouachita Mountains' conditions suit plants such as Tomato, Sweet Potato, Peach, Muscadine Grape, Blackberry. What actually thrives on any one site still turns on its specific soil, sun, and drainage — we score each plant against the real conditions at your address.
How is the Ouachita Mountains defined?
The Ouachita Mountains is defined here as a curated cluster of 9 neighboring counties that share a growing character. Growing regions have no official boundary, so this footprint is our published one — every county in it is named on this page.
Which states does the Ouachita Mountains cover?
The Ouachita Mountains spans Arkansas. Each state's full growing guide is linked on this page.
What other growing regions cover the same states?
Mississippi Delta, The Ozarks, West Gulf Coastal Plain (South Arkansas), Arkansas River Valley, and Crowley's Ridge share at least one state with the Ouachita Mountains. Growing regions overlap and interlock — a single address can sit inside more than one, which is why the precise read is always the parcel, not the region.
What this page reads at the Ouachita Mountains’s own scale
6 of the readings below were taken at the Ouachita Mountains' own scale — the zone 7b-8a band across its footprint, a median 245-day season across its 9 counties and 1,893 documented federal contamination records across its 9 counties, 439 of them in Garland County alone; one is borrowed from a wider read, named and linked below.
Measured here
- The USDA hardiness band 7b-8a aggregated across all 9 counties in the footprintUSDA PHZM 2023
- The boundary itself — the 9 counties this region is curated fromGrowable Ground subregion registry
- The growing character that makes this region distinct from the states it crossesGrowable Ground subregion registry
- The 28°F season across the footprint — the middle half of its 9 counties run 237 to 247 frost-free days, median 245NOAA Regional Climate Centers ACIS, 1991-2020
- The federal contamination record over the whole footprint — 1,893 documented federal contamination records across its 9 counties, 439 of them in Garland County aloneEPA, USGS and USDA federal site records
- The soil order mix across the footprint — 72% Ultisols, topsoil pH 5.0–5.8, area-weighted across its 9 mapped countiesUSDA NRCS SSURGO
Inherited from a wider read
- The candidate plant list — its state's curated sets, merged and filtered to zones 7b-8afrom Arkansas
What this page can’t tell you
- Which end of the 10-day range your ground sits at — 237 days at one extreme, 247 at the other, decided mostly by elevationfrost dates explained →
- Which of those soils your own ground sits on — the survey maps them county-wide, and they change across a drivewaysoil types explained →
- The soil pH, drainage, sun hours, and frost pockets on one specific lotwhy one lot differs from the next →
Explore the Ouachita Mountains
State growing guides
Counties in this region
Other growing regions across Arkansas
The flat, deep, dark alluvial bottomland of the lower Mississippi River — extraordinarily fertile cotton, soybean, rice, and sweet-potato ground.
A rugged Interior Highlands of cherty, rocky soils, oak-hickory forest, and clear streams — brambles, peaches, and tough hill gardens.
South Arkansas's pine Timberlands are the warmest, longest-season corner of the state — USDA zones 8a-8b with roughly 256-278 frost-free days (per county_data.json) — but the real signature is the ground: sandy, acidic, well-drained Coastal Plain soils under the pine belt, not the heavy dark alluvium of the Delta to the east or the rocky uplands to the north. That pairing — a long southern season on light, low-pH pine-flatwoods beds — pushes the playbook toward acid-tolerant and heat-loving Southern staples, raised quick-draining beds, and liming/organic-matter management that the Delta and mountain pages never need to cover. Around El Dorado, Camden, Magnolia, and Texarkana this is a distinct crop-and-soil story the statewide and tidal gulf-coast pages both miss.
The Arkansas River Valley — one of Arkansas's six natural divisions, threading the Arkansas River between the Ozark and Ouachita Mountains — spans USDA zones 7b to 8a across its eight member counties, with frost-free seasons of roughly 243 to 254 days.
A loess ridge rising two hundred feet out of the Delta's flatness — the well-drained upland that carried Arkansas's historic orchards, running 7b-8a from Piggott to Helena through country that is otherwise alluvial bottomland; the differentiator is the ground itself: deep, drained loess where the Delta holds water.