Frio County, in Texas, sits in USDA hardiness zone 9a — room for a real mix of vegetables, fruit, and perennials matched to the local frost calendar.
A short list that earns its place here — artichoke, fig, california poppy, and cabbage — with any one site's soil, sun, and drainage making the final cut.
Frio County lies within the South Texas Plains / Brush Country (Rio Grande Plains) — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Frio County holds more than one microclimate.
Soils and elevations shift across Frio 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 Frio County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Frio County — the short answer
Frio County, Texas: USDA zone 9a, about 302 days between hard freezes, across 725K acres.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Feb 8
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Dec 7
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~302
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 725K 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 9a is Frio County's average, not your lot's — a low corner or a tree line moves it. Against Frio County's 302-day season, see what your own ground reads.
Heat and winter chill in Frio County
Across a year, Frio County accumulates about 7,614 growing degree days above 50°F, about 1,790 more than the middle Texas county — ahead of 225 of Texas’s 254 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 373 hours below 45°F, 722 fewer than the Texas middle of 1,095. 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 Frio County
Across Frio County, the ground is predominantly Alfisols, where Duval, Webb, and Zavco are the most extensive named soil series. The soil is generally well drained with a very fine sandy loam surface. Topsoil pH runs about 6.5–7.5, neutral. Rainfall drains through hydrologic group C soils.
Soil order
Alfisols
Drainage
Well drained
Prime farmland
27%
Hydric soils
0%
Soil still varies lot by lot — soil types explained.
How the ground varies across Frio County
The USDA soil survey maps 92% of Frio County as well drained — but another 8% drains differently: 7% moderately well drained.
Duval is the most extensive named soil at 26% of mapped acres, then Webb (10%) and Zavco (6%).
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 Frio County
Each reading below is measured for Frio 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 Frio County are well drained, in hydrologic group C — 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 Frio County runs about pH 6.5–7.5, 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
MeasuredFrio County runs about 302 days between hard freezes — close to year-round growing.
Frost is rarely the limit here; winter plantings are as real as summer ones, and the harder question is which crops shrug off the summer heat.
Grow cool-season crops through the mild winter, and choose heat-tolerant varieties for the summer beds.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredFrio County sits in USDA hardiness zone 9a.
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 Frio County is in
Frio County sits in the Southern Texas Plains — EPA Level III, inside the wider Great Plains. One consistent ecological setting across the whole county.
What Grows in Frio County
We scored all 1,086 plants against Frio County's own USDA zone 9a and its own 302-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 Texas profile.
Is it too late to plant in Frio 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 Jan 11; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 8 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 7 — long-season crops need about 90 days of runway, quick greens only 30. With almost year-round growing weather, timing is about heat and rainfall more than frost — some bench is always in play.
What gets applied to farmland in Frio County
USGS estimates 30,893 lb of Glyphosate on Frio County farmland in 2019, its largest by weight, ahead of 2,4-d (11,786 lb) and Metolachlor & Metolachlor-s (8,214 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 Frio County — and how to grow with it.
We checked the federal record across Frio County — 154 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 Frio 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 Frio County
Closest first, across Frio County. Listing isn't leaking, and distance isn't exposure.
- THE WESTERN CO OF NORTH AMERICAUnderground Storage Tanks · 650 ft
- DILLEY YARDUnderground Storage Tanks · 650 ft
- ROAD & BRIDGE DEPTUnderground Storage Tanks · 650 ft
- NABORS FRIO FACILITYUnderground Storage Tanks · 650 ft
- GTSW-DILLEY CENTRAL OFFICEUnderground Storage Tanks · 650 ft
- GONZALES MOBIL STATIONUnderground Storage Tanks · 650 ft
- DILLEY FOOD MARTUnderground Storage Tanks · 650 ft
- DILLEY TEXACO STATIONUnderground Storage Tanks · 650 ft
- SAULS GULF SERVICE STATIONUnderground Storage Tanks · 650 ft
- AG SUPPLIES OF PEARSALLUnderground Storage Tanks · 650 ft
- DILLARDS OF DILLEYUnderground Storage Tanks · 650 ft
- TX DOT MAINTENCEUnderground Storage Tanks · 650 ft
6 more sites are on the record inside the same radius. See them on the map
Measured from Frio 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 Frio County.
Total Sites
154
across Frio County
Risk Level
Moderate
Highest-severity
4 Toxics Release Inventory facilities
Sources Checked
across Frio County
Severity Distribution
across Frio County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Frio County, Nitrate runs higher than the national average — 76 sites across Frio County. 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).
Check your specific parcel in Frio 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 Frio County average
Your land is one point inside Frio County
Everything above resolves to Frio County as a whole — one PHZM band and one county frost record, read across 725K 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 Frio County Average
Frio County Average
- ●USDA Zones 9a, averaged across Frio County
- ●One soil character for all of Frio County
- ●Frost dates read at Frio County's scale: Feb 8 to Dec 7
YOUR Parcel
- ✓Your exact zone, not Frio County's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Frio County
Pull a site-specific report for your exact address in Frio County, Texas — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Frio County averages can't show:
We read public map data around Frio County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Frio County average
How we know this about Frio 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 Frio County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Frio County
When does frost risk typically end in Frio County?
The last hard freeze (28°F) in Frio County typically lands around Feb 8, 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 Mar 1.
How long is the growing season in Frio County?
Measured between 28°F hard freezes, Frio County sees about 302 frost-free days — roughly Feb 8 through Dec 7, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Mar 1 to Nov 23, about 267 days.
Is the soil safe to grow vegetables in Frio County?
The federal record around Frio County shows 154 documented sites, mostly Nitrate entries (76), the nearest Underground Storage Tanks record about 0.1 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 Frio County's scale — its 9a band and its 302-day season. Your yard writes its own version of Frio 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 Texas's frost window, season length, and soil profile against the plant's real requirements.
What this page reads at Frio County’s own scale
8 of the readings below were taken at Frio County's own scale — its own ~302-day span between 28°F freezes, the 3 most extensive soil series mapped here and 154 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Frio County's own USDA hardiness band, zones 9aUSDA PHZM 2023
- Frio County's own 28°F hard-freeze dates and its ~302-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Frio CountyUSDA NRCS SSURGO
- 154 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 0.1 miles outFederal environmental registers
- Frio County's boundary and the 725,440 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~302-day seasonGrowable Ground crop-matching engine
- Frio County sitting wholly inside the Southern Texas PlainsUS EPA Level III Ecoregions
- Which agricultural compounds go onto Frio County farmland, and roughly how muchUSGS NAWQA EPest county estimates
Inherited from a wider read
- The growing challenges every Texas grower plans around — written at state scale, so they stay on the state guidefrom Texas
What this page can’t tell you
- How the season shifts across Frio County — the ~302 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 Frio County's 725,440 acreswhy one lot differs from the next →
- Which of those 154 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 Frio Countyread your own land →