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USDA hardiness zone lookup

San Antonio, TX — USDA Zone 9a

San Antonio, Texas · 272-day growing season

Frost dates and growing season in San Antonio

USDA hardiness zoneZone 9a
Average last spring frostFebruary 28
Average first fall frostNovember 27
Growing season length~272 days
Temperature range (F)20 to 30°F
Temperature range (C)-7 to -1°C

San Antonio spans USDA zones 8 to 9 across its ZIP codes (Zone 8b, Zone 9a); the city center sits in Zone 9a, so warmer and cooler pockets exist either side of that.

These are 50%-probability averages modeled from San Antonio's USDA hardiness zone and regional climate normals — not a single-station reading. In a typical year the last spring frost will have passed by February 28, but a colder-than-average year can run 1-2 weeks later. Plant tender crops (tomatoes, peppers, basil) once both soil and night temperatures are consistently warm — a thermometer beats the calendar.

Growing season in San Antonio

San Antonio, Texas sits in USDA Zone 9a, with roughly 272 frost-free days between an average last spring frost around February 28 and a first fall frost around November 27. That is a near year-round season — the limiting factor is summer heat, not frost, so schedule cool-season crops for winter and protect tender ones from extreme highs. San Antonio lies near 29.4°N; higher-latitude gardens get longer midsummer days but a tighter shoulder season at this zone. As a large metro, the built-up core typically runs up to half a zone warmer than outlying suburbs through the urban heat-island effect — sheltered city gardens often push tender crops a little earlier than the average suggests.

What grows in San Antonio

San Antonio falls in USDA Zone 9a, so the same hardiness constraints apply as the full Zone 9 guide. Vegetables, herbs, and fruit trees rated to Zone 9a (or hardier) will overwinter here in a typical year.

What to plant in San Antonio this week

San Antonio is in high summer — most spring plantings are in. Keep an eye on watering and start planning your fall crop. Cool-season seedlings (broccoli, cabbage, lettuce) can be started indoors for a fall transplant.

Full planting calendar for San Antonio

Crop-by-crop sowing, transplant, and harvest dates calibrated to zone 9 averages:

ZIP codes in San Antonio

Drill down to the precise frost window and planting calendar for a specific ZIP in San Antonio:

Local microclimate notes

Zone tables give you the average — but San Antoniogardens vary. South-facing walls and paved areas can run a full half-zone warmer than the published rating. Low-lying spots, frost pockets, and shaded north sides can run colder. If you've gardened here a few seasons, your own frost record — the last time you actually got frost damage — beats any national average.

Source and methodology

Hardiness zone from the USDA Plant Hardiness Zone Map (2023 revision). Frost-date and growing-season figures are modeled from San Antonio's USDA hardiness zone and regional NOAA 1991-2020 climate normals — zone-level estimates, not a per-station record, so treat them as planning guidance and confirm against your own local frost history. Crop recommendations draw on US Cooperative Extension references, curated by the Growli editorial team. Last reviewed June 2026.

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