USDA zone 10a in Texas
USDA plant hardiness zone 10a covers 18 locations across Texas (average annual extreme minimum 30 to 35 °F): Alton, TX, Brownsville, TX, Corpus Christi, TX, Corpus Christi, TX, Harlingen, TX, La Coma Heights, TX, and 12 more. Average last spring frost across this group ranges January 8 (Lasana) to January 31 (Sullivan), and growing seasons run 321–362 days (Sullivan to Port Mansfield) — even within one state, because hardiness sets winter survival, not planting dates. The table below gives every Texas location's own frost dates; the printable planting calendar uses Lyford, this group's median-season location.
- USDA zone
- 10a30 to 35 °F
- Last frost range
- Jan 8–Jan 31avg, 32°F
- First frost range
- Jan 1–Dec 29avg, 32°F
- Growing season range
- 321–362days
Locations in this group
Every location below shares this zone and a nearby weather station, but keeps its own frost dates — find your town for its own numbers, or use the ZIP planner on the home page for an instant personalized answer.
| Location | Also covers | Nearest station | Last frost | First frost | Season (days) |
|---|---|---|---|---|---|
| Alton | Salida del Sol Estates, Citrus | La Joya | Jan 23 | Dec 28 | 340 |
| Brownsville | Rancho Viejo, San Pedro, Reid Hope King | Brownsville | frost-free | frost-free | 365 |
| Corpus Christi | Falman | Port Aransas | frost-free | frost-free | 365 |
| Corpus Christi | Tierra Grande | Corpus Christi Nas | frost-free | frost-free | 365 |
| Harlingen | San Benito, Combes, Los Indios | Harlingen | frost-free | frost-free | 365 |
| La Coma Heights | — | Edinburg 17 Nne | Jan 21 | Dec 23 | 338 |
| La Tina Ranch | Bayview | Port Isabel Cameron Ap | frost-free | frost-free | 365 |
| Laguna Heights | — | Port Isabel | frost-free | frost-free | 365 |
| Lasana | — | Harlingen Rio Grande Ap | Jan 8 | Dec 29 | 357 |
| Lyford * | Lasara, San Perlita, Los Angeles | Raymondville | Jan 21 | Dec 26 | 340 |
| McAllen | Edinburg, Donna, La Joya | Mcallen | frost-free | frost-free | 365 |
| McAllen | Mission, Pharr, Hidalgo, South Alamo | Mcallen Miller Intl Ap | frost-free | frost-free | 365 |
| Mercedes | La Feria, La Blanca, Olivarez, Progreso, Laguna Seca, Monte Alto, +5 more | Santa Rosa 3 Wnw | Jan 10 | Dec 27 | 355 |
| Port Mansfield | — | Port Mansfield | Jan 12 | Jan 1 | 362 |
| Portland | Tierra Grande | Corpus Christi | Jan 28 | Dec 21 | 331 |
| Rockport | — | Rockport Aransas Co Ap | Jan 23 | Jan 1 | 347 |
| Sullivan | La Grulla, Los Ebanos | Rio Grande City | Jan 31 | Dec 17 | 321 |
| Texas | Bolivar Peninsula, Galveston, Tiki Island | Galveston Scholes Fld | frost-free | frost-free | 365 |
* Lyford is this group's median-season location — the calendar below is computed from its data.
Data: NOAA NCEI U.S. Climate Normals 1991–2020 (public domain) and USDA Plant Hardiness Zone Map 2023. Planting windows synthesized from U.S. Cooperative Extension guides.
Planting calendar (Lyford, representative)
Computed from Lyford's average frost dates — the median-season location in this Texaszone 10a group. hatched = start seeds indoors, solid green = plant out, teal = a fall sowing, and the terracotta dot marks the estimated first harvest. Ranges are extension-guide planning guidance, not guarantees — your own location's dates may run a week or two earlier or later (see the table above).
- Start indoors
- Plant out
- Fall sowing
- First harvest
| Crop | Frost tolerance | Start indoors | Plant out | First harvest | Fall planting | Season fit |
|---|---|---|---|---|---|---|
| Tomato | Tender | Jan 1 | Jan 28 – Feb 4 | Mar 29 – Apr 18 | — | matures comfortably |
| Pepper | Very tender | Jan 1 | Feb 4 – Feb 11 | Apr 5 – May 5 | — | matures comfortably |
| Cucumber | Tender | Jan 1 | Jan 28 – Feb 4 | Mar 19 – Apr 8 | — | matures comfortably |
| Summer squash / zucchini | Tender | — | Jan 28 – Feb 4 | Mar 14 – Mar 29 | — | matures comfortably |
| Bush bean | Tender | — | Jan 28 – Feb 4 | Mar 19 – Mar 29 | Oct 27 – Nov 6 | matures comfortably |
| Sweet corn | Tender | — | Jan 21 – Feb 4 | Mar 22 – Apr 21 | — | matures comfortably |
| Basil | Very tender | Jan 1 | Jan 28 – Feb 4 | Feb 27 – Mar 14 | — | matures comfortably |
| Lettuce | Half-hardy | Jan 1 | Jan 1 – Jan 7 | Feb 15 – Mar 2 | Oct 13 – Oct 28 | matures comfortably |
| Pea | Hardy | — | Jan 1 | Feb 25 – Mar 12 | Oct 3 – Oct 18 | matures comfortably |
| Spinach | Hardy | — | Jan 1 | Feb 10 – Feb 20 | Oct 23 – Nov 2 | matures comfortably |
| Carrot | Half-hardy | — | Jan 1 – Jan 7 | Mar 2 – Mar 22 | Sep 23 – Oct 13 | matures comfortably |
| Broccoli | Half-hardy | Jan 1 | Jan 1 – Jan 7 | Feb 25 – Mar 17 | Sep 28 – Oct 18 | matures comfortably |
Which crops fit this growing season
Using Lyford's own 340-day growing season (32°F, NOAA 1991–2020 median) against each crop's real days-to-maturity range: 12 of 12 crops mature here with comfortable margin. A different location in the table above with a longer or shorter season will get a different mix — the ZIP planner on the home page gives your own.
Frost & freeze dates (Lyford)
From NOAA's 1991–2020 Climate Normals at station USC00417458. The median (p50) is the average date; the 90%-safe column is the date the freeze has passed in about 9 years out of 10 — the conservative date to plant after or harvest before.
| Threshold | Last spring — avg | Last spring — 90%-safe | First fall — avg | First fall — 90%-safe | Season (days) |
|---|---|---|---|---|---|
| 36°F | Feb 15 | Mar 16 | Dec 8 | Jan 5 | 301 |
| 32°F (freeze) | Jan 21 | Feb 27 | Dec 26 | Feb 1 | 340 |
| 28°F | Jan 7 | Feb 8 | Jan 2 | Feb 1 | 365 |
| 24°F | Jan 7 | Jan 27 | Jan 5 | Jan 22 | 365 |
Growing degree days
Growing degree days (GDD) accumulate warmth above a base temperature over the year — a better predictor of crop development than the calendar alone. This group's median GDD (base 50°F) across all 18 locations is 9,041; Lyford's own reading is shown below.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 9,001 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 12,595 | cool-season crops (brassicas, greens) |
Hardiness zone 10a in Texas
Zone 10a means an average annual extreme minimum winter temperature of about 30 to 35 °F on the USDA's 2023 map — the number that tells you which perennials, shrubs, and trees reliably survive an average winter here. It does not set your planting dates, which come from the frost calendar above. Texas spans 9 hardiness zones in this dataset — see all Texas locations for the full range, including zones6b, 7a, 7b, 8a, 8b, 9a, 9b, 10b.
Explore zone 10a in other states at zone 10a, or see all USDA hardiness zones.
Frequently asked questions
- What does USDA hardiness zone 10a mean in Texas?
- Zone 10a means an average annual extreme minimum winter temperature of 30 to 35 °F — the standard USDA measure of which perennials survive winter. 18 locations in Texas fall in this zone. It does not set planting dates; see the frost calendar below for that.
- Where in Texas's zone 10a is the growing season longest?
- Port Mansfield runs the longest season on this page at about 362 days; Sullivan is shortest at about 321 days — they share the same hardiness zone, but they sit at different weather stations, so their frost calendars differ.
- When should I plant tomatoes in Texas's zone 10a?
- Using Lyford's frost dates (this page's median-season location): start seeds indoors about Jan 1, then transplant outside about Jan 28 – Feb 4. Your own location in the table above may differ by a week or two — use the ZIP planner on the home page for your exact station's dates.
- Does every location in Texas's zone 10a have the same frost dates?
- No — they do not all share a weather station, so frost dates vary by a week or more across the 18 locations listed (see the table above for each location's own dates).
Sources & method
Frost, freeze, growing-season, and growing-degree-day figures are NOAA NCEI U.S. Climate Normals 1991–2020, one reading per location's own nearest station (see the table above). The hardiness zone is the USDA Plant Hardiness Zone Map 2023, matched to each location's ZIP. Planting windows are computed by counting from the average last and first frost using per-crop offsets synthesized from U.S. Cooperative Extension guides — the full method and citations are on the methodology page.