Frost dates for 78666 — San Marcos, TX
Last spring frostFeb 28median date
First fall frostNov 29median date
Growing season274 daysfrost-free
Hardiness zone9aZone 9a
How San Marcos compares
- In 8 years out of 10, the last spring frost in San Marcos falls between February 1 and March 21, a 48-day window. The first fall frost falls between November 8 and December 21.
- The median last frost is 15 days earlier than the Texas median of Mar 15.
- Its 274-day growing season is longer than 84% of the 1,316 Texas places with a regular frost season (state median 245 days).
- The last frost is typical for zone 9a, where the median is Mar 3.
- The weather station records an average of 20 nights a year at or below 32°F.
- Compared with New Braunfels, TX, 25 km away, the last frost here is 8 days earlier than there and the growing season is 19 days longer.
Frost probability
| Chance of frost after | Date |
|---|---|
| 90% (early) | February 1 |
| 50% (median) | February 28 |
| 10% (safe for tender plants) | March 21 |
| Chance of frost before | Date |
|---|---|
| 10% (early) | November 8 |
| 50% (median) | November 29 |
| 90% (late) | December 21 |
Frost here means 32°F (0°C). A median date means half of years have their last frost earlier and half later.
Planting calendar for San Marcos, TX
Frost dates for 78666 — San Marcos, TX — last frost Feb 28, first frost Nov 29, zone 9a. whenisthelastfrost.com
Crop
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Start indoors: Dec 6 to Dec 20Transplant outside: Jan 31 to Feb 14
Start indoors: Dec 20 to Jan 3Start indoors: Dec 20 to Jan 3Transplant outside: Mar 14 to Mar 28
Start indoors: Dec 20 to Jan 3Start indoors: Dec 20 to Jan 3Transplant outside: Mar 14 to Mar 28
Start indoors: Jan 3 to Jan 17Transplant outside: Mar 7 to Mar 21
Start indoors: Jan 3 to Jan 17Transplant outside: Feb 7 to Feb 21Sow outdoors: Jan 31 to Mar 7Plant for fall: Oct 4 to Nov 1
Start indoors: Jan 3 to Jan 17Transplant outside: Jan 31 to Feb 14Sow outdoors: Jan 31 to Feb 14Plant for fall: Sep 20 to Oct 11
Start indoors: Jan 3 to Jan 17Transplant outside: Feb 14 to Feb 28Plant for fall: Aug 23 to Sep 13
Start indoors: Jan 3 to Jan 17Transplant outside: Feb 7 to Feb 21Plant for fall: Aug 23 to Sep 13
Start indoors: Jan 3 to Jan 17Transplant outside: Feb 14 to Feb 28Plant for fall: Aug 23 to Sep 13
Start indoors: Jan 17 to Jan 31Transplant outside: Mar 21 to Apr 4Sow outdoors: Mar 21 to Apr 4
Start indoors: Jan 17 to Jan 31Transplant outside: Mar 7 to Mar 21
Sow outdoors: Jan 17 to Feb 7Plant for fall: Sep 6 to Sep 27
Sow outdoors: Jan 17 to Feb 7Plant for fall: Oct 4 to Oct 25
Sow outdoors: Jan 24 to Mar 7Plant for fall: Oct 18 to Nov 8
Start indoors: Jan 31 to Feb 7Transplant outside: Mar 14 to Mar 21Sow outdoors: Mar 7 to Mar 21Plant for fall: Sep 13 to Sep 27
Start indoors: Jan 31 to Feb 7Sow outdoors: Mar 7 to Mar 21Plant for fall: Sep 20 to Oct 4
Start indoors: Jan 31 to Feb 7Sow outdoors: Mar 7 to Mar 21
Start indoors: Jan 31 to Feb 7Transplant outside: Mar 14 to Mar 28
Sow outdoors: Feb 7 to Mar 7Plant for fall: Sep 6 to Sep 20
Sow outdoors: Feb 7 to Mar 7Plant for fall: Sep 20 to Oct 4
Sow outdoors: Feb 7 to Feb 28
Sow outdoors: Feb 14 to Mar 14Plant for fall: Sep 20 to Oct 4
Sow outdoors: Feb 14 to Mar 7Plant for fall: Oct 4 to Oct 25
Sow outdoors: Mar 7 to Mar 28Plant for fall: Sep 13 to Sep 27
Sow outdoors: Mar 7 to Mar 21
Transplant outside: Mar 14 to Apr 4
Plant for fall: Nov 15 to Dec 20
Start indoorsTransplant outsideSow outdoorsPlant for fallMedian frost dates
When to plant vegetables in San Marcos, TX
| Crop | Start indoors | Transplant | Sow outdoors | Fall crop |
|---|---|---|---|---|
| Onions | Dec 6 – Dec 20 | Jan 31 – Feb 14 | — | — |
| Peppers | Dec 20 – Jan 3 | Mar 14 – Mar 28 | — | — |
| Eggplant | Dec 20 – Jan 3 | Mar 14 – Mar 28 | — | — |
| Tomatoes | Jan 3 – Jan 17 | Mar 7 – Mar 21 | — | — |
| Lettuce | Jan 3 – Jan 17 | Feb 7 – Feb 21 | Jan 31 – Mar 7 | Oct 4 – Nov 1 |
| Kale | Jan 3 – Jan 17 | Jan 31 – Feb 14 | Jan 31 – Feb 14 | Sep 20 – Oct 11 |
| Broccoli | Jan 3 – Jan 17 | Feb 14 – Feb 28 | — | Aug 23 – Sep 13 |
| Cabbage | Jan 3 – Jan 17 | Feb 7 – Feb 21 | — | Aug 23 – Sep 13 |
| Cauliflower | Jan 3 – Jan 17 | Feb 14 – Feb 28 | — | Aug 23 – Sep 13 |
| Okra | Jan 17 – Jan 31 | Mar 21 – Apr 4 | Mar 21 – Apr 4 | — |
| Basil | Jan 17 – Jan 31 | Mar 7 – Mar 21 | — | — |
| Peas | — | — | Jan 17 – Feb 7 | Sep 6 – Sep 27 |
| Spinach | — | — | Jan 17 – Feb 7 | Oct 4 – Oct 25 |
| Radishes | — | — | Jan 24 – Mar 7 | Oct 18 – Nov 8 |
| Cucumbers | Jan 31 – Feb 7 | Mar 14 – Mar 21 | Mar 7 – Mar 21 | Sep 13 – Sep 27 |
| Zucchini & Summer Squash | Jan 31 – Feb 7 | — | Mar 7 – Mar 21 | Sep 20 – Oct 4 |
| Winter Squash & Pumpkins | Jan 31 – Feb 7 | — | Mar 7 – Mar 21 | — |
| Melons & Watermelon | Jan 31 – Feb 7 | Mar 14 – Mar 28 | — | — |
| Carrots | — | — | Feb 7 – Mar 7 | Sep 6 – Sep 20 |
| Beets | — | — | Feb 7 – Mar 7 | Sep 20 – Oct 4 |
| Potatoes | — | — | Feb 7 – Feb 28 | — |
| Swiss Chard | — | — | Feb 14 – Mar 14 | Sep 20 – Oct 4 |
| Cilantro | — | — | Feb 14 – Mar 7 | Oct 4 – Oct 25 |
| Green Beans | — | — | Mar 7 – Mar 28 | Sep 13 – Sep 27 |
| Sweet Corn | — | — | Mar 7 – Mar 21 | — |
| Sweet Potatoes | — | Mar 14 – Apr 4 | — | — |
| Garlic | — | — | — | Nov 15 – Dec 20 |
Dates come from the median frost dates and common extension-service timing. Adjust for your soil temperature, microclimate and the varieties you grow.
About these dates
Based on 1991–2020 NOAA climate normals for the San Marcos, TX weather station, about 1 km away (elevation 666 ft (203 m)).
ZIP codes in San Marcos: 78666 78667
Frost dates near San Marcos
- Martindale Feb 28 · Nov 29
- Maxwell Feb 28 · Nov 29
- Staples Feb 28 · Nov 29
- Kyle Feb 28 · Nov 29
- Fentress Mar 5 · Nov 23
- Wimberley Mar 1 · Dec 1
- Kingsbury Mar 5 · Nov 23
- New Braunfels Mar 8 · Nov 18
Frequently asked questions
When is the last frost in San Marcos, TX?
The median last spring frost in San Marcos, TX is February 28. There is still about a 10% chance of frost after March 21, so wait until then to plant frost-tender crops like tomatoes and peppers.
When is the first frost in San Marcos, TX?
The median first fall frost is November 29, with about a 10% chance of frost before November 8.
How long is the growing season in San Marcos, TX?
About 274 days between the median last spring frost and first fall frost.
What planting zone is San Marcos, TX?
San Marcos, TX is in USDA hardiness zone 9a.