USDA Hardiness Zone 9a
Frost Dates for 78253 — San Antonio, Texas
Averages from San Antonio/Seaworld, Tx US, the nearest reporting station, 3.5 miles away.
Plant tender crops after February 18, and expect the first autumn freeze around December 9. That leaves about 296 frost-free days.
- Last spring frost
- February 18
- First fall frost
- December 9
- Growing season
- 296 days
- Hardiness zone
- 9a
50% probability
50% probability
frost-free
20 to 25°F annual low
Planting calendar for 78253
| When | What to do |
|---|---|
| December 10 – December 24 | Start peppers and aubergines indoors They need eight to ten weeks under lights before they can go out. |
| December 24 – January 7 | Start tomatoes indoors Six to eight weeks gives a transplant big enough to set fruit early. |
| January 21 – February 4 | Sow peas, spinach, lettuce, radish outdoors These tolerate light frost and prefer to germinate in cool soil. |
| February 18 onward | Transplant tomatoes, peppers, basil, squash, cucumbers The average last freeze has passed — still watch the actual forecast. |
| by September 16 | Sow the autumn crop of carrots, beets and brassicas They need about twelve weeks to size up before growth stops. |
| by November 25 | Harvest tender crops, or be ready to cover them A first freeze two weeks early is well within normal variation. |
| December 9 onward | Plant garlic, mulch beds, lift tender bulbs Garlic wants a cold spell; bare soil loses structure over winter. |
What these dates mean
Wait until after February 18 to put tender plants — tomatoes, peppers, basil, squash — in the ground. That is the date by which half of years in San Antonio, Texas are past their last freeze. Harvest before December 9, which leaves roughly 296 frost-free days.
ZIP 78253 sits in USDA hardiness zone 9a, meaning the average coldest night of the year falls between 20 to 25°F. Zone decides what survives the winter; frost dates decide when to plant each spring. They are different questions, and a plant can pass one and fail the other.
These are thirty-year NOAA averages for 1991–2020, not a forecast. Any individual year can frost two to three weeks either side of these dates, so check the actual forecast before planting out.