Castroville, Texas, sits in USDA hardiness zone 9a — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Expect artichoke, fig, california poppy, and cabbage to be strong candidates here; the deciding factors on any one parcel stay local — soil, sun, and drainage.
Even in Castroville, 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 Castroville 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 Castroville — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Castroville — the short answer
Castroville, Texas: USDA zone 9a, about 299 days between hard freezes, across 2K acres of city.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Feb 10
- Medina County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 6
- Medina County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~299
- Medina County normal — NOAA 1991–2020, nearest to this town
- City 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 Medina County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9a is Castroville's average, not your lot's — a low corner or a tree line moves it. Against Castroville's 299-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Castroville
Each reading below is measured for Castroville itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsCastroville runs about 299 days between hard freezes (read from Medina County, the closest normal to Castroville) — 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
MeasuredCastroville 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 Castroville is in
Castroville sits in the Texas Blackland Prairies — EPA Level III, inside the wider Great Plains. That is read at Castroville's own centroid, and it is not what its county reads: Medina County is mostly Southern Texas Plains. The wider page above you is answering a different question about different ground.
What Grows in Castroville
Every plant below cleared Castroville's own zone 9a and its 299-day season. Each card opens that plant's Texas profile. How we score.
Is it too late to plant in Castroville?
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 13; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 10 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 6 — 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 Castroville
Survey cells within 31 miles of Castroville checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 689 miles off. What to watch for.
What's on the federal record near Castroville
Closest first, within ~10 miles of Castroville. Listing isn't leaking, and distance isn't exposure.
- CORNER STORE 1822Underground Storage Tanks · 1800 ft
- WALMART SUPERCENTER 4102Underground Storage Tanks · 1900 ft
- WALMART SUPERCENTER 4102Brownfields · 2000 ft
- KELLER GRAINUnderground Storage Tanks · 2100 ft
- RUDYS CHEVRONUnderground Storage Tanks · 2200 ft
- BIGS 103Underground Storage Tanks · 2600 ft
- VALLEY MART 4Underground Storage Tanks · 0.7 mi
- ROYCE GROFF OILUnderground Storage Tanks · 0.7 mi
- TD-68-42-109Nitrate · 1.0 mi
- CASTROVILLE MUNICIPAL AIRPORTUnderground Storage Tanks · 1.1 mi
- GASGO MARKETS 4Underground Storage Tanks · 1.2 mi
- INDUSTRY STATE BANKUnderground Storage Tanks · 1.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Castroville'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 Castroville.
Sources Checked
within ~10 miles of Castroville
Severity Distribution
within ~10 miles of Castroville
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Castroville, Nitrate runs higher than the national average — 100 sites within ~10 miles of Castroville. That's not a problem with your land — it's information about 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 Castroville
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 Castroville average
Your land is one point inside Castroville
Everything above resolves to Castroville as a whole — one PHZM band, read across 2K acres, with hard-freeze dates borrowed from Medina County’s record because no 30-year normal resolves at this city’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 city 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 Castroville Average
Castroville Average
- ●USDA Zones 9a, averaged across Castroville
- ●One soil character for all of Castroville
- ●Frost dates read at Castroville's scale: Feb 10 to Dec 6
YOUR Parcel
- ✓Your exact zone, not Castroville's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Castroville
Pull a site-specific report for your exact address in Castroville, Texas — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Castroville averages can't show:
We read public map data around Castroville — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Castroville average
How we know this about Castroville
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Medina 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 city grain anywhere on this page — there is no city-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 Castroville
When does frost risk typically end in Castroville?
The last hard freeze (28°F) in Castroville typically lands around Feb 10, 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 3.
When is the first frost in Castroville?
The first hard freeze (28°F) in Castroville typically arrives around Dec 6, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 22, so the watching starts about Nov 6 — about 299 days after the spring freeze cleared.
How long is the growing season in Castroville?
Measured between 28°F hard freezes, Castroville sees about 299 frost-free days — roughly Feb 10 through Dec 6, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Mar 3 to Nov 22, about 264 days.
Is the soil safe to grow vegetables in Castroville?
The federal record around Castroville is a meaningful one — 173 documented sites, mostly Nitrate entries (100), the nearest Underground Storage Tanks record about 0.3 miles 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.
How do I protect my plants from frost in Castroville?
From about Nov 6 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 6 (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 6. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Castroville's scale — its 9a band and its 299-day season. Your yard writes its own version of Castroville'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 Castroville’s own scale
6 of the readings below were taken at Castroville's own scale — the 2,269 acres it covers and 173 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Castroville's own USDA hardiness band, zones 9aUSDA PHZM 2023
- 173 documented contamination sites on the federal record near Castroville, the closest Underground Storage Tanks record about 0.3 miles out from the town centreFederal environmental registers
- Castroville's boundary and the 2,269 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~299-day seasonGrowable Ground crop-matching engine
- Castroville sits in the Texas Blackland Prairies — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
- Lanternfly survey cells around Castroville checked, none carrying a detectionlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- The 28°F hard-freeze dates — Castroville has no normal of its own, so its county's is the closest measured readfrom Medina County
- Soil character — no town-scale survey exists, so Castroville's 2,269 acres read through its county's SSURGO summaryfrom Medina County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Medina 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 Medina County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Castroville's 2,269 acreswhy one lot differs from the next →
- Which side of Castroville you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 2,269 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.3 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 Castroville-wide figureread your own land →
More in Texas
Wider growing context
What grows across TexasCastroville sits outside our named growing regions, so Texas as a whole is its closest context here.