Duval County, in Texas, sits in USDA hardiness zone 9b — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Expect okra, meyer lemon, california poppy, and artichoke to be strong candidates here; the deciding factors on any one parcel stay local — soil, sun, and drainage.
Duval County lies within the South Texas Plains / Brush Country (Rio Grande Plains) and the Coastal Bend — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Duval County holds more than one microclimate.
Soils and elevations shift across Duval 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 Duval County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Duval County — the short answer
Duval County, Texas: USDA zone 9b, about 319 days between hard freezes, across 1.1M acres.
- USDA zone
- 9b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jan 29
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Dec 14
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~319
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 1.1M 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 9b is Duval County's average, not your lot's — a low corner or a tree line moves it. Against Duval County's 319-day season, see what your own ground reads.
Heat and winter chill in Duval County
Across a year, Duval County accumulates about 8,281 growing degree days above 50°F, about 2,457 more than the middle Texas county — ahead of 242 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 53 hours below 45°F, 1,042 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 Duval County
Across Duval County, the ground is predominantly Mollisols, where Benavides, Delmita, and Piedras are the most extensive named soil series. The soil is generally well drained with a fine sandy loam surface. Topsoil pH runs about 7.0–7.9, slightly alkaline. Rainfall drains through hydrologic group B soils.
Soil order
Mollisols
Drainage
Well drained
Prime farmland
1%
Hydric soils
0%
Soil still varies lot by lot — soil types explained.
How the ground varies across Duval County
The USDA soil survey maps 90% of Duval County as well drained — but another 10% drains differently: 10% moderately well drained.
Benavides is the most extensive named soil at 13% of mapped acres, then Delmita (9%) and Piedras (9%).
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 Duval County
Each reading below is measured for Duval 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 Duval County are well 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 Duval County runs about pH 7.0–7.9, on the alkaline side.
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
Season length
MeasuredDuval County runs about 319 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
MeasuredDuval County sits in USDA hardiness zone 9b.
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 Duval County is in
Duval County spans 2 EPA Level III ecoregions — Southern Texas Plains (86%) and Western Gulf Coastal Plain (14%). 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 Duval County
We scored all 1,086 plants against Duval County's own USDA zone 9b and its own 319-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 Duval County?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Jan 1; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Jan 29 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 14 — 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 Duval County
USGS estimates 6,528 lb of 2,4-d on Duval County farmland in 2019, its largest by weight, ahead of Glyphosate (5,642 lb) and Atrazine (825 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 Duval County — and how to grow with it.
We checked the federal record across Duval County — 192 documented sites across 5 of the 9 source types we track.
The most significant on record: 1 concentrated animal feeding operation. Large-scale animal operations that can contaminate soil and groundwater with nitrates and pathogens.
The federal record across Duval 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 Duval County
Closest first, across Duval County. Listing isn't leaking, and distance isn't exposure.
- J D WHITEUnderground Storage Tanks · 0.7 mi
- LUIS LEAL STOREUnderground Storage Tanks · 0.7 mi
- RAMIREZ DRIVE INNUnderground Storage Tanks · 0.7 mi
- KOCH FREER STATIONUnderground Storage Tanks · 0.7 mi
- THE COUNTRY STOREUnderground Storage Tanks · 0.7 mi
- PALANGANA URANIUM OPERATIONSUnderground Storage Tanks · 0.7 mi
- EL MESQUITE PLANTUnderground Storage Tanks · 0.7 mi
- GONZALEZ GROCERYUnderground Storage Tanks · 0.7 mi
- CONOCOUnderground Storage Tanks · 0.7 mi
- MRS MARIA G GRACIAUnderground Storage Tanks · 0.7 mi
- WR PETERS FACILITYUnderground Storage Tanks · 0.7 mi
- L R GARZAUnderground Storage Tanks · 0.7 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Duval 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 Duval County.
Total Sites
192
across Duval County
Risk Level
Moderate
Highest-severity
1 concentrated animal feeding operation
Sources Checked
across Duval County
Severity Distribution
across Duval County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Duval County, Nitrate runs higher than the national average — 130 sites across Duval 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 Duval 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 Duval County average
Your land is one point inside Duval County
Everything above resolves to Duval County as a whole — one PHZM band and one county frost record, read across 1.1M 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 Duval County Average
Duval County Average
- ●USDA Zones 9b, averaged across Duval County
- ●One soil character for all of Duval County
- ●Frost dates read at Duval County's scale: Jan 29 to Dec 14
YOUR Parcel
- ✓Your exact zone, not Duval County's 9b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Duval County
Pull a site-specific report for your exact address in Duval County, Texas — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Duval County averages can't show:
We read public map data around Duval County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Duval County average
How we know this about Duval 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 Duval County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Duval County
When does frost risk typically end in Duval County?
The last hard freeze (28°F) in Duval County typically lands around Jan 29, 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 Feb 19.
How long is the growing season in Duval County?
Measured between 28°F hard freezes, Duval County sees about 319 frost-free days — roughly Jan 29 through Dec 14, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 19 to Nov 30, about 284 days.
Is the soil safe to grow vegetables in Duval County?
The federal record around Duval County shows 192 documented sites, mostly Nitrate entries (130), the nearest Underground Storage Tanks 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 Duval County's scale — its 9b band and its 319-day season. Your yard writes its own version of Duval 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 Duval County’s own scale
8 of the readings below were taken at Duval County's own scale — its own ~319-day span between 28°F freezes, the 3 most extensive soil series mapped here and 192 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Duval County's own USDA hardiness band, zones 9bUSDA PHZM 2023
- Duval County's own 28°F hard-freeze dates and its ~319-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Duval CountyUSDA NRCS SSURGO
- 192 documented contamination sites inside the county boundary, distance-sorted from its center — the closest Underground Storage Tanks record about 0.7 miles outFederal environmental registers
- Duval County's boundary and the 1,147,824 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9b and a ~319-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Duval County spans, Southern Texas Plains the largestUS EPA Level III Ecoregions
- Which agricultural compounds go onto Duval 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 Duval County — the ~319 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 Duval County's 1,147,824 acreswhy one lot differs from the next →
- Which of those 192 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 Duval Countyread your own land →