Starr County, in Texas, sits in USDA hardiness zone 9b — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
Crops well matched to these conditions include okra, meyer lemon, california poppy, and artichoke — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Starr County lies within the Rio Grande Valley — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring · NOAA 1991–2020 Climate Normals
Starr County holds more than one microclimate.
Soils and elevations shift across Starr 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 Starr County — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Starr County — the short answer
Starr County, Texas: USDA zone 9b, about 322 days between hard freezes, across 783K acres.
- USDA zone
- 9b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jan 21
- NOAA 1991–2020 Climate Normals, 28°F
- First hard freeze (28°F)
- Dec 9
- NOAA 1991–2020 Climate Normals, 28°F
- Days between freezes
- ~322
- NOAA 1991–2020 Climate Normals, 28°F
- County area
- 783K 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 Starr County's average, not your lot's — a low corner or a tree line moves it. Against Starr County's 322-day season, see what your own ground reads.
Heat and winter chill in Starr County
Across a year, Starr County accumulates about 8,904 growing degree days above 50°F, about 3,080 more than the middle Texas county — ahead of 250 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 0 hours below 45°F, 1,095 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 Starr County
Across Starr County, the ground is predominantly Inceptisols, where McAllen, Copita, and Zapata are the most extensive named soil series. The soil is generally well drained with a fine sandy loam surface. Topsoil pH runs about 7.6–8.2, slightly alkaline. Rainfall drains through hydrologic group B soils.
Soil order
Inceptisols
Drainage
Well drained
Prime farmland
1%
Hydric soils
1%
Soil still varies lot by lot — soil types explained.
How the ground varies across Starr County
The USDA soil survey maps 88% of Starr County as well drained — but another 12% drains differently: 10% moderately well drained, 1% somewhat poorly drained.
McAllen is the most extensive named soil at 33% of mapped acres, then Copita (14%) and Zapata (8%).
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 Starr County
Each reading below is measured for Starr 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 Starr 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 Starr County runs about pH 7.6–8.2, 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
MeasuredStarr County runs about 322 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
MeasuredStarr 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 Starr County is in
Starr County spans 2 EPA Level III ecoregions — Southern Texas Plains (93%) and Western Gulf Coastal Plain (7%). 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 Starr County
We scored all 1,086 plants against Starr County's own USDA zone 9b and its own 322-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 Starr County?
For most of the year, no — what changes is which crops still fit the days remaining. 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 21 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 9 — 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.
Documented around Starr County
- monarch butterfly13 documented records
Sighting records, so they follow observers as much as insects.
What gets applied to farmland in Starr County
USGS estimates 25,986 lb of Glyphosate on Starr County farmland in 2019, its largest by weight, ahead of Metolachlor & Metolachlor-s (10,589 lb) and Metolachlor-s (6,387 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 Starr County — and how to grow with it.
We checked the federal record across Starr County — 179 documented sites across 5 of the 9 source types we track.
The most significant on record: 1 Toxics Release Inventory facility. Active industrial facilities reporting chemical releases to air, water, and land.
There's a meaningful federal record across Starr 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.
What's on the federal record near Starr County
Closest first, across Starr County. Listing isn't leaking, and distance isn't exposure.
- RIO WSCPFAS · 25 ft
- CITY OF RIO GRANDE CITYPFAS · 25 ft
- UNION WSCPFAS · 25 ft
- TRIANGLE TRADING POSTUnderground Storage Tanks · 2.2 mi
- A & F MARTUnderground Storage Tanks · 2.2 mi
- A & L COUNTRY STOREUnderground Storage Tanks · 2.2 mi
- HIGH HILL GROCERYUnderground Storage Tanks · 2.2 mi
- SAENZ EXXONUnderground Storage Tanks · 2.2 mi
- LA LOMITAUnderground Storage Tanks · 2.2 mi
- J G AUTO SERVICESUnderground Storage Tanks · 2.2 mi
- GARCIAS DRIVE INNUnderground Storage Tanks · 2.2 mi
- MENDOZAS GROCERYUnderground Storage Tanks · 2.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Starr 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 Starr County.
Total Sites
179
across Starr County
Risk Level
Elevated
Highest-severity
1 Toxics Release Inventory facility
Sources Checked
across Starr County
Severity Distribution
across Starr County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Starr County, two things run higher than the national average across Starr County — PFAS (6 sites) and CAFO (3 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
CAFO: CAFOs pose a different contamination profile than chemical sources.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Wash all produce consumed raw thoroughly, especially leafy greens grown near CAFOs.
Check your specific parcel in Starr 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 Starr County average
Your land is one point inside Starr County
Everything above resolves to Starr County as a whole — one PHZM band and one county frost record, read across 783K 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 Starr County Average
Starr County Average
- ●USDA Zones 9b, averaged across Starr County
- ●One soil character for all of Starr County
- ●Frost dates read at Starr County's scale: Jan 21 to Dec 9
YOUR Parcel
- ✓Your exact zone, not Starr County's 9b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Starr County
Pull a site-specific report for your exact address in Starr County, Texas — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Starr County averages can't show:
We read public map data around Starr County — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Starr County average
How we know this about Starr 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 Starr County carries no record of its own, the figure is inherited and labelled — the resolution ledger below names each.
Common questions about Starr County
When does frost risk typically end in Starr County?
The last hard freeze (28°F) in Starr County typically lands around Jan 21, 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 11.
How long is the growing season in Starr County?
Measured between 28°F hard freezes, Starr County sees about 322 frost-free days — roughly Jan 21 through Dec 9, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 11 to Nov 25, about 287 days.
Is the soil safe to grow vegetables in Starr County?
The federal record around Starr County is a meaningful one — 179 documented sites, mostly Underground Storage Tanks entries (158), the nearest PFAS record under a tenth of a mile out — 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.
Everything above is measured at Starr County's scale — its 9b band and its 322-day season. Your yard writes its own version of Starr 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 Starr County’s own scale
9 of the readings below were taken at Starr County's own scale — its own ~322-day span between 28°F freezes, the 3 most extensive soil series mapped here and 179 documented sites inside its boundary; one is borrowed from a wider read, named and linked below.
Measured here
- Starr County's own USDA hardiness band, zones 9bUSDA PHZM 2023
- Starr County's own 28°F hard-freeze dates and its ~322-day span between themNOAA 1991–2020 Climate Normals
- The soil order, drainage, surface pH, and the 3 most extensive named soil series mapped in Starr CountyUSDA NRCS SSURGO
- 179 documented contamination sites inside the county boundary, distance-sorted from its center — the closest PFAS record under a tenth of a mile outFederal environmental registers
- Starr County's boundary and the 782,834 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9b and a ~322-day seasonGrowable Ground crop-matching engine
- The 2 ecoregions Starr County spans, Southern Texas Plains the largestUS EPA Level III Ecoregions
- Open occurrence records documented in Starr County for a tracked speciesGBIF derived datasets (CC0 / CC BY 4.0)
- Which agricultural compounds go onto Starr 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 Starr County — the ~322 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 Starr County's 782,834 acreswhy one lot differs from the next →
- Which of those 179 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 Starr Countyread your own land →