Karnes, TX planting calendar
- USDA zone
- 9a20 to 25 °F
- Last frost
- Feb 16avg, 32°F
- First frost
- Dec 9avg, 32°F
- Growing season
- 300days
Karnes, Texas is in USDA plant hardiness zone 9a. Its average last spring frost is around February 16 and the first fall frost around December 9, giving a growing season of about 300 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.
Karnes planting calendar
Each crop's windows are counted from Karnes'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 5 | Feb 23 – Mar 2 | Apr 24 – May 14 | — |
| Pepper | Very tender | Jan 1 | Mar 2 – Mar 9 | May 1 – May 31 | — |
| Cucumber | Tender | Jan 19 – Jan 26 | Feb 23 – Mar 2 | Apr 14 – May 4 | — |
| Summer squash / zucchini | Tender | — | Feb 23 – Mar 2 | Apr 9 – Apr 24 | — |
| Bush bean | Tender | — | Feb 23 – Mar 2 | Apr 14 – Apr 24 | Oct 10 – Oct 20 |
| Sweet corn | Tender | — | Feb 16 – Mar 2 | Apr 17 – May 17 | — |
| Basil | Very tender | Jan 5 – Jan 19 | Feb 23 – Mar 2 | Mar 25 – Apr 9 | — |
| Lettuce | Half-hardy | Jan 5 – Jan 19 | Jan 19 – Feb 2 | Mar 5 – Mar 20 | Sep 26 – Oct 11 |
| Pea | Hardy | — | Jan 5 – Jan 19 | Mar 1 – Mar 16 | Sep 16 – Oct 1 |
| Spinach | Hardy | — | Jan 5 – Jan 19 | Feb 14 – Feb 24 | Oct 6 – Oct 16 |
| Carrot | Half-hardy | — | Jan 26 – Feb 2 | Mar 27 – Apr 16 | Sep 6 – Sep 26 |
| Broccoli | Half-hardy | Jan 1 – Jan 5 | Jan 19 – Feb 2 | Mar 15 – Apr 4 | Sep 11 – Oct 1 |
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 USC00414696. 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 | Mar 4 | Mar 28 | Nov 27 | Dec 16 | 267 |
| 32°F (freeze) | Feb 16 | Mar 13 | Dec 9 | Jan 10 | 300 |
| 28°F | Jan 28 | Mar 2 | Dec 27 | Feb 3 | 337 |
| 24°F | Jan 13 | Feb 13 | Jan 4 | Feb 6 | 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) | 7,588 | standard warm-season base (tomato, corn, beans) |
| Base 40°F (cool-season) | 11,073 | cool-season crops (brassicas, greens) |
Hardiness zone 9a
Karnes sits in USDA plant hardiness zone 9a on the 2023 map — meaning its average annual extreme minimum winter temperature is about 20 to 25 °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 9a, or see all USDA hardiness zones.
Frequently asked questions
- What USDA hardiness zone is Karnes?
- Karnes, Texas is in USDA plant hardiness zone 9a on the 2023 map (average annual extreme minimum temperature 20 to 25 °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 Karnes?
- The average (median) last spring frost at 32°F is around February 16, from NOAA's 1991–2020 climate normals at the nearest reporting station. Roughly one year in ten the last frost is as late as March 13, so wait until then before setting out frost-tender plants if you want to be safe.
- When is the first fall frost in Karnes?
- The average first fall frost at 32°F is around December 9. That leaves a growing season of about 300 days between the average last spring and first fall frosts.
- When should I start tomatoes in Karnes?
- Start tomato seeds indoors about Jan 1 – Jan 5 and transplant them outside about Feb 23 – Mar 2, once the danger of frost has passed. Estimated first harvest is around Apr 24 – May 14.
- How long is the growing season in Karnes?
- About 300 days at the 32°F threshold (NOAA 1991–2020, median) — the span between the average last spring frost (~February 16) and the average first fall frost (~December 9). 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 USC00414696 (Karnes City 2n, 5.2 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.