The South Texas Plains / Brush Country (Rio Grande Plains) spans USDA hardiness zones 9a-9b — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
Unlike the irrigated citrus delta of the Lower Rio Grande Valley or the Gulf-moist Coastal Bend prairie, the Brush Country is South Texas at its hottest and driest — Zone 9a–9b with roughly 300–327 frost-free days, yet only about 18–24 inches of rain a year over caliche soils. The growing calendar inverts here: summer is the season to survive with drip irrigation and heat-adapted natives like mesquite and huisache, while the nationally known Winter Garden district around Dimmit, Zavala, and Frio counties grows spinach and onions straight through the winter when most of the state lies dormant. Well-matched crops include okra, black-eyed pea, tomato, and jalapeno, and the gap between "grows in the area" and "grows in your yard" is closed by soil, sun, and drainage.
The South Texas Plains / Brush Country (Rio Grande Plains) spans Texas.
Your yard isn't all of the South Texas Plains / Brush Country (Rio Grande Plains).
The South Texas Plains / Brush Country (Rio Grande Plains) spans USDA zones 9a-9b, 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 South Texas Plains / Brush Country (Rio Grande Plains) — soil, climate, flood, and parcel records. How we handle your address.
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The South Texas Plains / Brush Country (Rio Grande Plains) — the short answer
The South Texas Plains / Brush Country (Rio Grande Plains): USDA zones 9a-9b, 297–327 frost-free days depending where in it you stand, in Texas.
- USDA zones
- 9a-9b
- USDA PHZM 2023, aggregated over the footprint
- Shortest season here
- 297 days
- NOAA Regional Climate Centers ACIS, 1991-2020 — Uvalde 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 South Texas Plains / Brush Country (Rio Grande Plains) is not one growing season
One answer for the South Texas Plains / Brush Country (Rio Grande Plains) averages 9 counties whose growing seasons are 30 days apart — from 297 frost-free days in Uvalde County to 327 in Zapata 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 307–319 days, with a median of 310 days — a 30-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 South Texas Plains / Brush Country (Rio Grande Plains)
The middle half of the South Texas Plains / Brush Country (Rio Grande Plains) runs 307–319 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 307 frost-free days
2 counties
- Uvalde County · 297 days
- Frio County · 302 days
The end of the region that sets the planting calendar — start seed indoors here and the season stretches to meet the crop.
307–319 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 319 frost-free days
2 counties
- Zapata County · 327 days
- Webb County · 326 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 South Texas Plains / Brush Country (Rio Grande Plains)
All 5 of the plants below that publish a season requirement clear even Uvalde County’s 297 frost-free days — so on season alone, this grid works at both ends of the region. The 30-day spread still decides how far past this list you can push, and how early you can start.
Plants matched to the South Texas Plains / Brush Country (Rio Grande Plains)'s USDA zones 9a-9b, 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 South Texas Plains / Brush Country (Rio Grande Plains)
Plants the USDA PLANTS Database documents as native and present in this region’s state, kept only where the published hardiness range meets the South Texas Plains / Brush Country (Rio Grande Plains)’s USDA zones 9a-9b — 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 South Texas Plains / Brush Country (Rio Grande Plains)
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 Mollisols, at 29% of mapped acres, followed by Alfisols (28%), Inceptisols (16%) and Vertisols (15%). 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 Duval, Maverick, and Catarina.
75% of those acres are well drained, and another 22% moderately well drained. Topsoil pH runs 6.5–8.2 between the lowest and the highest county on record. 6% of the footprint is classed prime farmland.
Soil order
Mollisols
Drainage
Well drained
Topsoil pH
6.5–8.2
Hydric soils
0%
Soil changes across a driveway, so which of these your own ground sits on is a parcel question rather than a regional one. Maverick County holds the most wetland ground here, at 0% — soil types explained.
USDA NRCS SSURGO via Soil Data Access
What this means for growing in the South Texas Plains / Brush Country (Rio Grande Plains)
The soil survey reads this ground county by county, and the readings above are those records summed across the South Texas Plains / Brush Country (Rio Grande Plains). Here is what they mean for a garden here — and the move an experienced grower makes about each one.
Drainage
From county records75% of the mapped acres across the South Texas Plains / Brush Country (Rio Grande Plains) 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 South Texas Plains / Brush Country (Rio Grande Plains) runs pH 6.5–8.2 — alkaline in seven of its nine counties.
Many vegetables cope, but acid-lovers like blueberries struggle, and iron and manganese lock up above about pH 7.5 — leaves yellow between the veins even in rich soil.
Elemental sulfur and generous organic matter lower pH slowly for the beds that need it; test first so you add only what the soil actually calls for.
USDA NRCS SSURGO
Safe to Grow Here?
What the federal record shows across the South Texas Plains / Brush Country (Rio Grande Plains) — and how to grow with it.
Across the South Texas Plains / Brush Country (Rio Grande Plains)'s 9 counties the federal record holds 1,934 documented sites, mostly Underground Storage Tanks (904), Nitrate (716) and Brownfields (261). The heaviest single county is Webb County, with 653.
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 South Texas Plains / Brush Country (Rio Grande Plains) to see which records sit where you actually grow.
Sources Checked
Summed across the 9 counties in the South Texas Plains / Brush Country (Rio Grande Plains)
A note from Gnorman
What an experienced grower watches for around here
In and around the South Texas Plains / Brush Country (Rio Grande Plains), Nitrate runs higher than the national average — 716 sites across the 9 counties in the South Texas Plains / Brush Country (Rio Grande Plains). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around 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).
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Your land is one point inside the South Texas Plains / Brush Country (Rio Grande Plains)
Everything above resolves to the South Texas Plains / Brush Country (Rio Grande Plains) as a whole — a footprint whose own counties record seasons 30 days apart, and hardiness across zones 9a-9b. 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 South Texas Plains / Brush Country (Rio Grande Plains) Average
South Texas Plains / Brush Country (Rio Grande Plains) Average
- ●USDA Zones 9a-9b, averaged across South Texas Plains / Brush Country (Rio Grande Plains)
- ●One soil character for all of South Texas Plains / Brush Country (Rio Grande Plains)
- ●State-average frost dates
YOUR Parcel
- ✓Your exact zone, not South Texas Plains / Brush Country (Rio Grande Plains)'s 9a-9b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in the South Texas Plains / Brush Country (Rio Grande Plains)
Pull a site-specific report for your exact address in the South Texas Plains / Brush Country (Rio Grande Plains) — soil, sun, drainage, frost risk, contamination, and scored plant recommendations.
Three things about your lot that South Texas Plains / Brush Country (Rio Grande Plains) averages can't show:
We read public map data around The South Texas Plains / Brush Country (Rio Grande Plains) — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the South Texas Plains / Brush Country (Rio Grande Plains) average
How we know this about the South Texas Plains / Brush Country (Rio Grande Plains)
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 South Texas Plains / Brush Country (Rio Grande Plains)
What hardiness zone is the South Texas Plains / Brush Country (Rio Grande Plains)?
The South Texas Plains / Brush Country (Rio Grande Plains) spans USDA hardiness zones 9a-9b, 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 South Texas Plains / Brush Country (Rio Grande Plains)?
Measured between 28°F hard freezes, the South Texas Plains / Brush Country (Rio Grande Plains)'s counties mostly run 307 to 319 frost-free days, median 310 (NOAA Regional Climate Centers ACIS, 1991–2020, over 9 member counties). That 12-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 South Texas Plains / Brush Country (Rio Grande Plains)?
Across the South Texas Plains / Brush Country (Rio Grande Plains), the middle half of member counties see their last 28°F hard freeze between Jan 29 and Feb 4 (median Feb 2), and their first fall freeze between Dec 8 and Dec 10. Those are hard freezes, not the last light frost: tender transplants wait for about Feb 23, and elevation decides which end of a 6-day spread you garden in.
What grows well in the South Texas Plains / Brush Country (Rio Grande Plains)?
The South Texas Plains / Brush Country (Rio Grande Plains)'s conditions suit plants such as Okra, Black-eyed Pea, Tomato, Jalapeno, Sweet Potato, Rosemary. 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 South Texas Plains / Brush Country (Rio Grande Plains) defined?
The South Texas Plains / Brush Country (Rio Grande Plains) 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 South Texas Plains / Brush Country (Rio Grande Plains) cover?
The South Texas Plains / Brush Country (Rio Grande Plains) spans Texas. Each state's full growing guide is linked on this page.
What other growing regions cover the same states?
High Plains, Piney Woods, Texas High Plains / Panhandle, Gulf Coast, Blackland Prairie, and Coastal Bend share at least one state with the South Texas Plains / Brush Country (Rio Grande Plains). 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 South Texas Plains / Brush Country (Rio Grande Plains)’s own scale
6 of the readings below were taken at the South Texas Plains / Brush Country (Rio Grande Plains)'s own scale — the zone 9a-9b band across its footprint, a median 310-day season across its 9 counties and 1,934 documented federal contamination records across its 9 counties, 653 of them in Webb County alone; one is borrowed from a wider read, named and linked below.
Measured here
- The USDA hardiness band 9a-9b 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 307 to 319 frost-free days, median 310NOAA Regional Climate Centers ACIS, 1991-2020
- The federal contamination record over the whole footprint — 1,934 documented federal contamination records across its 9 counties, 653 of them in Webb County aloneEPA, USGS and USDA federal site records
- The soil order mix across the footprint — 29% Mollisols, topsoil pH 6.5–8.2, 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 9a-9bfrom Texas
What this page can’t tell you
- Which end of the 12-day range your ground sits at — 307 days at one extreme, 319 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 South Texas Plains / Brush Country (Rio Grande Plains)
State growing guides
Counties in this region
Other growing regions across Texas
A semi-arid shortgrass tableland of deep soils and big sky, where wind, low rainfall, and irrigation shape dryland wheat, sorghum, and resilient gardens.
The sandy, acidic pine-and-hardwood forest belt of East Texas and western Louisiana — the humid South Central Plains, where a long frost-free season of roughly nine months favors heat- and acid-tolerant Southern gardens.
The southern, warmer anchor of the High Plains — the Llano Estacado tableland west of the Caprock Escarpment, where a longer season (frost-free days run near 227 across the Texas counties, well above the multi-state High Plains average) and deep-well Ogallala irrigation define the growing reality. This is the largest contiguous cotton patch in the world around Lubbock (Texas Co-op Power), and, west of the Caprock, the Texas High Plains AVA (TTB, 27 CFR 9.144) that grows roughly 80% of the state's wine grapes. High, flat, and semi-arid: what grows here is what deep-well water and a zone 7a-8a season can coax from it, a distinctly Texan story rather than the dryland wheat and sorghum of the northern High Plains.
The humid, near-frost-free coastal rim of the Gulf of Mexico — long seasons, sandy and alluvial soils, heat, and hurricanes shaping what thrives. (Representative coastal counties, not exhaustive.)
Here the soil, not the zone, defines the garden. The Blackland Prairie is a narrow black-clay belt tracing the I-35 corridor from Sherman through Dallas, Waco, and Temple down to Austin — built on vertisol "black gumbo" that swells sticky when wet, then cracks open as it dries. That shrink-swell clay is alkaline and slow-draining, so where the sandy acid soils of the Piney Woods to the east or the thin limestone of the Hill Country to the west let many gardeners plant straight in the ground, growers here reach for raised beds, gypsum, and heavy organic amendment first. The season runs long — commonly 264 to 300 frost-free days across zones 8a to 9a — but it's the black clay, not the calendar, your beds have to answer to.
The 11 counties of Texas's Coastal Bend, anchored on Corpus Christi and the Nueces estuary, span USDA hardiness zones 9a to 10a with frost-free seasons running 311 to 343 days.