Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated

Planting zone for 78009 — Castroville, TX

ZIP code 78009 (Castroville, Medina County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is February 24 and the first fall frost December 2.

Where ZIP 78009 is

Outlined: the ZIP code area · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zone9a20 to 25 °F
Coldest night−6.7 to −3.9 °C
Last frostFeb 24
First frostDec 2
2012 zone8b

Was 8b on the 2012 map — half a zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 9a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Castroville, TX…

Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Castroville, TX

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostFebruary 24median — 50% chance of a later frost
Safe for tender plantsMarch 14only 10% chance of frost after
First fall frostDecember 2median — 10% chance by Nov 14
Growing season283 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 4 and returns around December 18.

From the NOAA station Lytle 3w, TX — 9 miles away, elevation 722 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in 78009

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 13 – Jan 27
SpinachSow outdoors · Jan 13 – Feb 3
Broccoli, cabbageStart indoors · Dec 16 – Dec 30
Broccoli, cabbageTransplant · Feb 3 – Feb 17
Onion setsPlant outdoors · Jan 27 – Feb 10
PotatoesPlant outdoors · Feb 3 – Feb 17
LettuceSow outdoors · Jan 27 – Feb 10
Carrots, beetsSow outdoors · Feb 3 – Feb 17
TomatoesStart indoors · Dec 30 – Jan 13
TomatoesTransplant · Mar 3 – Mar 17
Peppers, eggplantStart indoors · Dec 16 – Dec 30
Peppers, eggplantTransplant · Mar 10 – Mar 24
BeansSow outdoors · Mar 3 – Mar 17
Sweet cornSow outdoors · Mar 3 – Mar 17
Cucumbers, squashSow outdoors · Mar 3 – Mar 17
Fall lettuce, spinachSow outdoors · Oct 7 – Oct 21
GarlicPlant cloves · Nov 18 – Dec 23
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 24) and first fall frost (Dec 2) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 78009 came on Jan 29 — 4 days later than the 1991–2020 average (Jan 25).

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Soil in Castroville, TX

The soil mapped at the center of ZIP 78009 is Atco — loam, well drained.

TextureLoama good balance for most vegetables
pH8.2alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2%moderate
Hydrologic groupBwater soaks in moderately
Farmland classFarmland of statewide importance, if irrigatedUSDA classification

Map unit: Atco loam, 0 to 1 percent slopes.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 78009; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Castroville, TX

Summer high96 °Faverage high, July
Winter low42 °Faverage low, January
Hot days120days a year at 90 °F or more
Freezing nights17nights a year at 32 °F or less
Growing degree days7,659base 50 °F — the season’s usable heat
Longest day14 h 02 mindaylight on June 21
Shortest day10 h 16 mindaylight on December 21
Onions to growShort-daysummer days stay under about 14 h 20 min, so long-day varieties won’t bulb
Precipitation31.8 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°100°110°32 °FJanuary: average high 66 °F, low 42 °F 66°42° JanFebruary: average high 70 °F, low 45 °F 70°45° FebMarch: average high 77 °F, low 52 °F 77°52° MarApril: average high 83 °F, low 59 °F 83°59° AprMay: average high 87 °F, low 67 °F 87°67° MayJune: average high 94 °F, low 72 °F 94°72° JunJuly: average high 96 °F, low 73 °F 96°73° JulAugust: average high 96 °F, low 73 °F 96°73° AugSeptember: average high 91 °F, low 69 °F 91°69° SepOctober: average high 84 °F, low 60 °F 84°60° OctNovember: average high 74 °F, low 51 °F 74°51° NovDecember: average high 67 °F, low 43 °F 67°43° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 1.87 in precipitation 1.9 JanFebruary: 1.60 in precipitation 1.6 FebMarch: 2.24 in precipitation 2.2 MarApril: 2.50 in precipitation 2.5 AprMay: 4.17 in precipitation 4.2 MayJune: 3.79 in precipitation 3.8 JunJuly: 2.50 in precipitation 2.5 JulAugust: 2.34 in precipitation 2.3 AugSeptember: 2.78 in precipitation 2.8 SepOctober: 3.77 in precipitation 3.8 OctNovember: 2.37 in precipitation 2.4 NovDecember: 1.90 in precipitation 1.9 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Lytle 3w, TX (9 mi away); precipitation: Castroville 1.3 Ssw, TX (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 9a.

780399a
La Coste, TX · 5 mi
780669a
Rio Medina, TX · 9 mi
782459a
San Antonio, TX · 9 mi
782539a
San Antonio, TX · 9 mi
780029a
Atascosa, TX · 11 mi
782529a
San Antonio, TX · 12 mi
780549a
Macdona, TX · 12 mi
780569a
Mico, TX · 12 mi

Texas planting zones →

Questions about 78009

What planting zone is ZIP code 78009?

ZIP code 78009 (Castroville, TX) is in USDA hardiness zone 9a on the 2023 map: the coldest night of an average winter reaches 20 to 25 °F (−6.7 to −3.9 °C).

When is the last frost in Castroville, TX?

The median last spring frost (32 °F) near 78009 is February 24; after March 14 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Lytle 3w station.

When is the first frost in Castroville, TX?

The median first fall frost near 78009 is December 2, giving a median frost-free growing season of 283 days.

When should I plant tomatoes in 78009?

Start tomato seeds indoors around Dec 30 – Jan 13 and set transplants outside around Mar 3 – Mar 17, one to three weeks after the median last frost.

How much rain and snow does 78009 get?

About 31.8 inches of precipitation a year (NOAA 1991–2020 normals, Castroville 1.3 Ssw station).

How hot do summers get in Castroville, TX?

The average high peaks at 96 °F in July, with about 120 days a year at 90 °F or more.

What kind of soil does 78009 have?

The USDA soil survey maps Atco at the center of ZIP 78009: loam, well drained, pH about 8.2 (alkaline).

Did spring come early in Castroville, TX in 2026?

Spring leaf-out near 78009 came on Jan 29 in 2026, 4 days later than the 1991–2020 average (Jan 25), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Castroville, TX?

Short-day onions: the longest day near 78009 is 14 h 02 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.

Did the zone for 78009 change?

Yes. The 2012 USDA map put 78009 in zone 8b; the 2023 map puts it in zone 9a. The newer map uses 1991–2020 data and more weather stations.