San Antonio, Texas: planting zone & frost dates
San Antonio is in USDA plant hardiness zone 9a, where the average coldest winter night reaches 20 to 25°F (-6.7 to -3.9°C). The typical last spring frost is around Mar 5 and the first fall frost around Nov 18.
Frost dates
| Probability | Last spring frost (32°F) | First fall frost (32°F) |
|---|---|---|
| Safer (10% risk) | Mar 19 | Nov 7 |
| Typical planning date (30% risk) | Mar 5 | Nov 18 |
| Median (50%) | Feb 25 | Nov 28 |
How to read this: after the spring "10% risk" date, a 32°F frost happens in only about 1 year in 10. In fall, the "10% risk" date is the early end — a frost before it happens about 1 year in 10.
Frost data comes from NOAA station SAN ANTONIO INCARNATE WORD, TX (USC00417947), 3.2 mi (5.1 km) from the city center and 20 ft lower than the city center (-6 m). Record used for the 1991–2020 normals: 16 years.
Why your yard may differ from the station: microclimates.
Hardiness zone across San Antonio
San Antonio spans more than one half-zone. Share of the city's land area by zone (via its 55 ZIP codes): 9a (95%), 8b (5%). The headline zone is the one covering the most land. Look up your ZIP for your exact zone.
ZIP codes in San Antonio and their zones
| ZIP | Zone | Share of city land |
|---|---|---|
| 78023 | 8b | 4.7% |
| 78223 | 9a | 4.0% |
| 78221 | 9a | 3.4% |
| 78258 | 9a | 3.1% |
| 78264 | 9a | 3.1% |
| 78224 | 9a | 3.0% |
| 78251 | 9a | 3.0% |
| 78247 | 9a | 2.9% |
| 78259 | 9a | 2.9% |
| 78216 | 9a | 2.8% |
| 78249 | 9a | 2.8% |
| 78219 | 9a | 2.7% |
| 78222 | 9a | 2.7% |
| 78227 | 9a | 2.7% |
| 78257 | 9a | 2.4% |
| 78218 | 9a | 2.2% |
| 78228 | 9a | 2.2% |
| 78073 | 9a | 2.1% |
| 78211 | 9a | 2.0% |
| 78217 | 9a | 2.0% |
| 78230 | 9a | 2.0% |
| 78240 | 9a | 2.0% |
| 78250 | 9a | 1.9% |
| 78233 | 9a | 1.8% |
| 78112 | 9a | 1.6% |
| 78214 | 9a | 1.6% |
| 78232 | 9a | 1.6% |
| 78238 | 9a | 1.6% |
| 78242 | 9a | 1.6% |
| 78207 | 9a | 1.5% |
| 78210 | 9a | 1.5% |
| 78220 | 9a | 1.4% |
| 78237 | 9a | 1.4% |
| 78256 | 9a | 1.4% |
| 78201 | 9a | 1.3% |
| 78209 | 9a | 1.3% |
| 78212 | 9a | 1.3% |
| 78229 | 9a | 1.2% |
| 78245 | 9a | 1.2% |
| 78254 | 9a | 1.2% |
| 78213 | 9a | 1.1% |
| 78226 | 9a | 1.1% |
| 78109 | 9a | 1.0% |
| 78234 | 9a | 1.0% |
| 78252 | 9a | 1.0% |
| 78266 | 9a | 1.0% |
| 78248 | 9a | 0.8% |
| 78202 | 9a | 0.5% |
| 78204 | 9a | 0.5% |
| 78225 | 9a | 0.4% |
| 78235 | 9a | 0.4% |
| 78203 | 9a | 0.3% |
| 78205 | 9a | 0.2% |
| 78208 | 9a | 0.2% |
| 78215 | 9a | 0.2% |
Vegetable planting calendar for San Antonio
Dates are counted from the 30%-risk frost dates above (last frost Mar 5, first frost Nov 18). Shift a week later in cold spots or low-lying ground.
| Crop | Start indoors | Transplant / plant out | Direct sow | Fall crop sow/plant |
|---|---|---|---|---|
| Tomato | Jan 8 – Jan 22 | Mar 12 – Mar 26 | — | — |
| Pepper | Dec 25 – Jan 8 | Mar 19 – Apr 2 | — | — |
| Lettuce | Jan 22 – Feb 5 | Feb 19 – Mar 12 | Feb 5 – Mar 19 | Sep 9 – Oct 7 |
| Green Beans | — | — | Mar 12 – Apr 16 | Aug 26 – Sep 9 |
| Sweet Corn | — | — | Mar 12 – Apr 9 | — |
| Zucchini & Summer Squash | Feb 5 – Feb 12 | Mar 12 – Mar 26 | Mar 12 – Apr 2 | Aug 26 – Sep 9 |
| Cucumber | Feb 5 – Feb 12 | Mar 19 – Mar 26 | Mar 12 – Apr 2 | Aug 26 – Sep 9 |
| Carrot | — | — | Feb 12 – Mar 19 | Aug 26 – Sep 9 |
| Onion | Dec 11 – Dec 25 | Feb 5 – Feb 19 | — | — |
| Potato | — | Feb 5 – Feb 26 | — | — |
| Basil | Jan 22 – Feb 5 | Mar 19 – Apr 2 | Mar 19 – Apr 9 | — |
| Spinach | — | — | Jan 22 – Feb 19 | Sep 23 – Oct 21 |
| Kale | Jan 8 – Jan 22 | Feb 5 – Feb 26 | Feb 5 – Feb 26 | Sep 9 – Oct 7 |
| Broccoli | Jan 8 – Jan 22 | Feb 19 – Mar 12 | — | Aug 26 – Sep 9 |
| Peas | — | — | Jan 22 – Feb 12 | Sep 9 – Sep 23 |
| Eggplant | Dec 25 – Jan 8 | Mar 19 – Apr 2 | — | — |
| Cabbage | Jan 8 – Jan 22 | Feb 5 – Feb 19 | — | Aug 26 – Sep 9 |
| Radish | — | — | Jan 29 – Mar 19 | Oct 7 – Nov 4 |
| Strawberry | — | Feb 5 – Feb 26 | — | — |
| Beets | — | — | Feb 12 – Mar 26 | Sep 9 – Sep 23 |
Nearby cities in Texas
- New Braunfels — zone 9a, last frost Mar 18, first frost Nov 10
- Austin — zone 9a, last frost Mar 2, first frost Nov 26
- Cedar Park — zone 9a, last frost Mar 19, first frost Nov 13
- Leander — zone 9a, last frost Mar 15, first frost Nov 16
- Round Rock — zone 9a, last frost Mar 19, first frost Nov 13
- Georgetown — zone 9a, last frost Mar 15, first frost Nov 16
More: all Texas cities · other zone 9a cities: Austin, TX, Seattle, WA, Las Vegas, NV, Portland, OR, Tucson, AZ, Baton Rouge, LA, Tallahassee, FL, Mobile, AL
San Antonio gardening questions
When is the last frost in San Antonio, TX?
Plan around Mar 5. At NOAA's San Antonio Incarnate Word, TX station, 3.2 mi from the city center, there is a 30% chance of a 32°F frost after that date. Half of springs have their last frost by Feb 25, and after Mar 19 the risk drops to about 1 in 10. A hard freeze (28°F) usually ends earlier, around Feb 5. Springs here are erratic: 50 days separate the 90% and 10% dates, versus a median of 36 days for cities on this site, so watch the forecast rather than the calendar.
When should I plant tomatoes in San Antonio, TX?
Start seeds indoors Jan 8 – Jan 22 and set transplants outside Mar 12 – Mar 26, once nights stay above 50°F and the soil is near 60°F. That leaves 258 days between the 30% frost dates, enough for most varieties including 80–85-day slicers. More: tomato planting dates by zone.
How long is the growing season in San Antonio?
About 277 days without a 32°F frost in a typical (median) year. In 9 years out of 10 the season lasts at least 249 days, and in 1 year in 10 it runs 313 days or more. In fall there is a 10% chance of frost by Nov 7 and a 30% chance by Nov 18. That ranks 20th longest of 55 Texas cities on this site.
When should I plant a fall garden in San Antonio?
Count back from the first fall frost (Nov 18): transplant broccoli Aug 26 – Sep 9; sow kale Sep 9 – Oct 7; sow lettuce Sep 9 – Oct 7; sow radishes Oct 7 – Nov 4. Hardy crops keep growing through light frosts; the median 28°F hard freeze here is Dec 15. How the math works: succession and fall planting.
Did San Antonio's hardiness zone change on the 2023 map?
Yes. Most of San Antonio was zone 8b on the 2012 map and is zone 9a on the 2023 map — half a zone warmer, like about 56% of U.S. ZIP codes. The shift comes from a newer 1991–2020 averaging period plus more weather stations and better mapping; it does not mean last frost comes earlier. Why the 2023 map is warmer.
Is all of San Antonio in zone 9a?
No. Zone 9a covers about 95% of the city's land; the rest is in 8b (5%), measured across the city's 55 ZIP codes. Check your own ZIP code in the table above or with the ZIP lookup.