USDA hardiness zone lookup
Harlingen, TX — USDA Zone 9b
Harlingen, Texas · 313-day growing season
Frost dates and growing season in Harlingen
| USDA hardiness zone | Zone 9b |
|---|---|
| Average last spring frost | February 5 |
| Average first fall frost | December 15 |
| Growing season length | ~313 days |
| Temperature range (F) | 20 to 30°F |
| Temperature range (C) | -7 to -1°C |
All of Harlingen's mapped ZIP codes fall in the same hardiness band, Zone 9b.
These are 50%-probability averages modeled from Harlingen's USDA hardiness zone and regional climate normals — not a single-station reading. In a typical year the last spring frost will have passed by February 5, but a colder-than-average year can run 1-2 weeks later. Plant tender crops (tomatoes, peppers, basil) once both soil and night temperatures are consistently warm — a thermometer beats the calendar.
Growing season in Harlingen
Harlingen, Texas sits in USDA Zone 9b, with roughly 313 frost-free days between an average last spring frost around February 5 and a first fall frost around December 15. That is a near year-round season — the limiting factor is summer heat, not frost, so schedule cool-season crops for winter and protect tender ones from extreme highs.
What grows in Harlingen
Harlingen falls in USDA Zone 9b, so the same hardiness constraints apply as the full Zone 9 guide. Vegetables, herbs, and fruit trees rated to Zone 9b (or hardier) will overwinter here in a typical year.
- Tomatoes (year-round in many areas)
- Peppers (all year)
- Citrus (oranges, lemons, limes, grapefruit)
- Avocado
- Mango (warmer areas)
- Banana
- Sweet potatoes
- Okra
- Southern peas
- Pomegranates
What to plant in Harlingen this week
Harlingen is in high summer — most spring plantings are in. Keep an eye on watering and start planning your fall crop. Cool-season seedlings (broccoli, cabbage, lettuce) can be started indoors for a fall transplant.
- When to plant tomatoes in zone 9
- When to plant peppers in zone 9
- When to plant bush beans in zone 9
- When to plant cucumbers in zone 9
- When to plant basil in zone 9
Full planting calendar for Harlingen
Crop-by-crop sowing, transplant, and harvest dates calibrated to zone 9 averages:
- When to plant tomatoes in zone 9
- When to plant peppers in zone 9
- When to plant basil in zone 9
- When to plant garlic in zone 9
- When to plant lettuce in zone 9
- When to plant bush beans in zone 9
- When to plant cucumbers in zone 9
- When to plant summer squash in zone 9
- When to plant peas in zone 9
- When to plant carrots in zone 9
ZIP codes in Harlingen
Drill down to the precise frost window and planting calendar for a specific ZIP in Harlingen:
Local microclimate notes
Zone tables give you the average — but Harlingengardens vary. South-facing walls and paved areas can run a full half-zone warmer than the published rating. Low-lying spots, frost pockets, and shaded north sides can run colder. If you've gardened here a few seasons, your own frost record — the last time you actually got frost damage — beats any national average.
Source and methodology
Hardiness zone from the USDA Plant Hardiness Zone Map (2023 revision). Frost-date and growing-season figures are modeled from Harlingen's USDA hardiness zone and regional NOAA 1991-2020 climate normals — zone-level estimates, not a per-station record, so treat them as planning guidance and confirm against your own local frost history. Crop recommendations draw on US Cooperative Extension references, curated by the Growli editorial team. Last reviewed June 2026.
Other cities in Texas
- Abilene, TX — USDA Zone 8a
- Allen, TX — USDA Zone 8a
- Arlington, TX — USDA Zone 8a
- Austin, TX — USDA Zone 8b
- Brownsville, TX — USDA Zone 10a
- Bryan, TX — USDA Zone 8b
- Carrollton, TX — USDA Zone 8a
- College Station, TX — USDA Zone 8b
- Conroe, TX — USDA Zone 9a
- Corpus Christi, TX — USDA Zone 9b
- Dallas, TX — USDA Zone 8b
- Del Rio, TX — USDA Zone 9a
- All of Texas by zone