Mercedes, TX planting calendar
- USDA zone
- 10a30 to 35 °F
- Last frost
- Jan 10avg, 32°F
- First frost
- Dec 27avg, 32°F
- Growing season
- 355days
Mercedes, Texas is in USDA plant hardiness zone 10a. Its average last spring frost is around January 10 and the first fall frost around December 27, giving a growing season of about 355 days (NOAA 1991–2020 normals, 32°F, median). Start tender crops like tomatoes and peppers indoors weeks before the last frost and set them out afterward; sow hardy crops such as peas, spinach, and lettuce before it. The planner below turns those frost dates into a printable per-crop planting calendar.
Mercedes planting calendar
Each crop's windows are counted from Mercedes's average frost dates. 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.
- Start indoors
- Plant out
- Fall sowing
- First harvest
| Crop | Frost tolerance | Start indoors | Plant out | First harvest | Fall planting |
|---|---|---|---|---|---|
| Tomato | Tender | Jan 1 | Jan 17 – Jan 24 | Mar 18 – Apr 7 | — |
| Pepper | Very tender | Jan 1 | Jan 24 – Jan 31 | Mar 25 – Apr 24 | — |
| Cucumber | Tender | Jan 1 | Jan 17 – Jan 24 | Mar 8 – Mar 28 | — |
| Summer squash / zucchini | Tender | — | Jan 17 – Jan 24 | Mar 3 – Mar 18 | — |
| Bush bean | Tender | — | Jan 17 – Jan 24 | Mar 8 – Mar 18 | Oct 28 – Nov 7 |
| Sweet corn | Tender | — | Jan 10 – Jan 24 | Mar 11 – Apr 10 | — |
| Basil | Very tender | Jan 1 | Jan 17 – Jan 24 | Feb 16 – Mar 3 | — |
| Lettuce | Half-hardy | Jan 1 | Jan 1 | Feb 15 – Mar 2 | Oct 14 – Oct 29 |
| Pea | Hardy | — | Jan 1 | Feb 25 – Mar 12 | Oct 4 – Oct 19 |
| Spinach | Hardy | — | Jan 1 | Feb 10 – Feb 20 | Oct 24 – Nov 3 |
| Carrot | Half-hardy | — | Jan 1 | Mar 2 – Mar 22 | Sep 24 – Oct 14 |
| Broccoli | Half-hardy | Jan 1 | Jan 1 | Feb 25 – Mar 17 | Sep 29 – Oct 19 |
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.
Frost & freeze dates
From NOAA's 1991–2020 Climate Normals at station USC00418059. 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 (p10 for spring, p90 for fall) — 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 3 | Mar 8 | Dec 12 | Jan 12 | 316 |
| 32°F (freeze) | Jan 10 | Feb 24 | Dec 27 | Feb 1 | 355 |
| 28°F | Jan 1 | Feb 1 | Dec 29 | Jan 24 | 365 |
| 24°F | — | — | — | — | 365 |
32°F is the standard "freeze" line that damages tender crops; lighter 36°F frost can nip the most cold-sensitive plants, while hardy crops shrug off light frost down toward 28°F. Use the threshold that matches what you are protecting.
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. Warm-season crops need a long, warm GDD total; a short, cool GDD total favors greens and brassicas.
| Model | °F·days | Used for |
|---|---|---|
| Base 50°F (warm-season) | 9,080 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 12,680 | cool-season crops (brassicas, greens) |
Hardiness zone 10a
Mercedes sits in USDA plant hardiness zone 10a on the 2023 map — meaning its average annual extreme minimum winter temperature is about 30 to 35 °F. That number 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.
Explore more places in zone 10a, or see all USDA hardiness zones.
Frequently asked questions
- What USDA hardiness zone is Mercedes?
- Mercedes, Texas is in USDA plant hardiness zone 10a on the 2023 map (average annual extreme minimum temperature 30 to 35 °F) — from the USDA Plant Hardiness Zone Map 2023, matched to this location's ZIP. See the methodology page for sources.
- When is the last frost in Mercedes?
- The average (median) last spring frost at 32°F is around January 10, from NOAA's 1991–2020 climate normals at the nearest reporting station. Roughly one year in ten the last frost is as late as February 24, so wait until then before setting out frost-tender plants if you want to be safe.
- When is the first fall frost in Mercedes?
- The average first fall frost at 32°F is around December 27. That leaves a growing season of about 355 days between the average last spring and first fall frosts.
- When should I start tomatoes in Mercedes?
- Start tomato seeds indoors about Jan 1 and transplant them outside about Jan 17 – Jan 24, once the danger of frost has passed. Estimated first harvest is around Mar 18 – Apr 7.
- How long is the growing season in Mercedes?
- About 355 days at the 32°F threshold (NOAA 1991–2020, median) — the span between the average last spring frost (~January 10) and the average first fall frost (~December 27). Cold-hardy crops extend usable time at both ends; frost-tender crops fit inside it.
Sources & method
Frost, freeze, growing-season, and growing-degree-day figures are NOAA NCEI U.S. Climate Normals 1991–2020 for station USC00418059 (Santa Rosa 3 Wnw, 2.8 km away). The hardiness zone is the USDA Plant Hardiness Zone Map 2023, matched to this 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.