San Isidro, Texas, sits in USDA hardiness zone 9b — a zone band wide enough that plant choice, not possibility, is the interesting question.
Reliable performers under these conditions include okra, meyer lemon, california poppy, and artichoke; what your own ground favors still comes down to its soil, sun, and drainage.
Even in San Isidro, no two yards are alike.
A low spot, a south-facing slope, or a stand of trees moves the frost date and sun across a single San Isidro lot. 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 San Isidro — soil, climate, flood, and parcel records. How we handle your address.
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San Isidro — the short answer
San Isidro, Texas: USDA zone 9b, about 322 days between hard freezes, across 2K acres of town.
- USDA zone
- 9b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Jan 21
- Starr County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 9
- Starr County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~322
- Starr County normal — NOAA 1991–2020, nearest to this town
- Town area
- 2K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. No 30-year normal resolves at this town’s own centroid, so the hard-freeze dates are Starr County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9b is San Isidro's average, not your lot's — a low corner or a tree line moves it. Against San Isidro's 322-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in San Isidro
Each reading below is measured for San Isidro itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsSan Isidro runs about 322 days between hard freezes (read from Starr County, the closest normal to San Isidro) — 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
MeasuredSan Isidro 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 San Isidro is in
San Isidro sits in the Southern Texas Plains — EPA Level III, inside the wider Great Plains. That is read at San Isidro's own centroid rather than borrowed from Starr County.
What Grows in San Isidro
Every plant below cleared San Isidro's own zone 9b and its 322-day season. Each card opens that plant's Texas profile. How we score.
Is it too late to plant in San Isidro?
Usually not — gardeners here simply switch what goes in the ground as the season moves. 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. In a climate this gentle, “too late” hardly applies — the question becomes which crops prefer the cooler months ahead.
What's on the federal record near San Isidro
Closest first, within ~10 miles of San Isidro. Listing isn't leaking, and distance isn't exposure.
- FARM & RANCH SUPPLYUnderground Storage Tanks · 2500 ft
- KOCH PIPELINE, STARR(SUNFIELD) STATIONBrownfields · 1.5 mi
- BARNEYS DRIVE INNUnderground Storage Tanks · 1.9 mi
- FLINT HILLS RESOURCES DELMITA TERMINALBrownfields · 4.3 mi
- BP-87-13-601Nitrate · 7.8 mi
- BP-87-14-401Nitrate · 7.9 mi
Measured from San Isidro'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 San Isidro.
Sources Checked
within ~10 miles of San Isidro
Severity Distribution
within ~10 miles of San Isidro
Highest-Severity Sites
Know Before You Grow
- •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.
- •Underground tanks leak petroleum as they age — near a former filling station, test the soil.
Check your specific parcel in San Isidro
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 San Isidro average
Your land is one point inside San Isidro
Everything above resolves to San Isidro as a whole — one PHZM band, read across 2K acres, with hard-freeze dates borrowed from Starr County’s record because no 30-year normal resolves at this town’s own centroid. 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 town 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 local average.
Your Lot vs the San Isidro Average
San Isidro Average
- ●USDA Zones 9b, averaged across San Isidro
- ●One soil character for all of San Isidro
- ●Frost dates read at San Isidro's scale: Jan 21 to Dec 9
YOUR Parcel
- ✓Your exact zone, not San Isidro's 9b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in San Isidro
Pull a site-specific report for your exact address in San Isidro, Texas — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that San Isidro averages can't show:
We read public map data around San Isidro — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the San Isidro average
How we know this about San Isidro
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this town’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Starr County’s record, because none resolves here; boundaries and acreage from US Census TIGER/Line 2025; the contamination records from the federal sources named in their beats above. Soil is not read at town grain anywhere on this page — there is no town-resolution survey in our data, which is why you will find no soil grid here rather than a statewide one wearing a local label. The resolution ledger below names every figure this page inherited.
Common questions about San Isidro
When does frost risk typically end in San Isidro?
The last hard freeze (28°F) in San Isidro 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.
When is the first frost in San Isidro?
The first hard freeze (28°F) in San Isidro typically arrives around Dec 9, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 25, so the watching starts about Nov 9 — about 322 days after the spring freeze cleared.
How long is the growing season in San Isidro?
Measured between 28°F hard freezes, San Isidro 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 San Isidro?
The federal record around San Isidro is light — 8 documented sites across the 9 federal source types we checked, mostly Nitrate entries (4), the nearest Underground Storage Tanks record about 0.5 miles out — and proximity to a documented site is information, not a diagnosis of any one yard. Growing food here starts from a strong position; a soil test before new food beds settles any site-specific question.
How do I protect my plants from frost in San Isidro?
From about Nov 9 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Dec 9 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Dec 9. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at San Isidro's scale — its 9b band and its 322-day season. Your yard writes its own version of San Isidro's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
What this page reads at San Isidro’s own scale
5 of the readings below were taken at San Isidro's own scale — the 1,986 acres it covers and 8 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- San Isidro's own USDA hardiness band, zones 9bUSDA PHZM 2023
- 8 documented contamination sites on the federal record near San Isidro, the closest Underground Storage Tanks record about 0.5 miles out from the town centreFederal environmental registers
- San Isidro's boundary and the 1,986 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 ecoregion at San Isidro's own centroid, the Southern Texas PlainsUS EPA Level III Ecoregions
Inherited from a wider read
- The 28°F hard-freeze dates — San Isidro has no normal of its own, so its county's is the closest measured readfrom Starr County
- Soil character — no town-scale survey exists, so San Isidro's 1,986 acres read through its county's SSURGO summaryfrom Starr County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Starr County
- The growing challenges every Texas grower plans around — written at state scale, so they stay on the state guidefrom Texas
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Starr County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among San Isidro's 1,986 acreswhy one lot differs from the next →
- Which side of San Isidro you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,986 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.5 miles out, measured from the town centrehow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — measured at your address, and averaged away by any San Isidro-wide figureread your own land →
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