Frost Dates for Harlingen, TX 78550

Last spring frost January 19 · First fall frost January 22 · 3 frost-free days · USDA Zone 10a

Frost probability for 78550

Frost10%50%90%
Spring (last frost)February 19January 19—
Fall (first frost)December 12January 22—

Dates come from NOAA 1971–2000 freeze probabilities at the nearest reporting station (26.2 km away); the 50% date is the median year.

Frost dates by ZIP code in Harlingen, TX

ZIPLast spring frost (50%)First fall frost (50%)Zone
78550January 19January 2210a
78552January 19January 2210a

Month by month in Harlingen

MonthWhat to do
JanuaryPlant cool-season crops: lettuce, spinach, broccoli, peas, and carrots.
FebruaryDirect sow brassicas and root vegetables. Start warm-season seedlings indoors.
MarchTransplant warm-season crops outdoors. Sow beans, cucumbers, and squash.
AprilMain warm-season planting window. Direct sow melons and sweet corn.
MaySuccession plant lettuce. Keep beds irrigated as temperatures climb.
JuneMonitor for heat stress. Harvest zucchini and cucumbers frequently.
JulyHarvest regularly to encourage continued production. Watch for pests.
AugustStart fall cool-season crops: broccoli, kale, beets, and carrots.
SeptemberPlant fall lettuce, spinach, arugula, and radishes.
OctoberHarvest mature crops. Direct sow cold-tolerant greens.
NovemberPlant garlic and onion sets. Harvest cool-season crops through the month.
DecemberPlant cool-season crops for winter harvest. Plan next year's garden.

What grows in a 3-day season

Frequently Asked Questions

What is the last frost date for Harlingen, TX (ZIP 78550)?

The median last spring frost date for Harlingen, TX (ZIP code 78550) is around January 19. This is the 50th-percentile date — meaning half of all years see frost end before this date. Use the 10% and 90% dates to understand the full range of risk in your area.

What is the first fall frost date in Harlingen, TX?

The median first fall frost date for Harlingen, TX is around January 22. Plan to harvest or protect frost-sensitive crops like tomatoes and peppers at least a week before this date to avoid losses.

How long is the growing season in Harlingen, TX?

The frost-free growing season in Harlingen is about 3 days. This window — from your last spring frost to your first fall frost — is when warm-season vegetables thrive. Cold-hardy crops like kale, spinach, and peas can extend your season by weeks on either side.

What USDA hardiness zone is Harlingen, TX?

Based on frost date patterns, Harlingen falls approximately in 10a. USDA hardiness zones are determined by average annual minimum winter temperatures and guide both plant selection and planting timing for your location.

When should I start tomatoes indoors in Harlingen, TX?

Start tomato seeds indoors 6–8 weeks before your last frost date (around January 19). For Harlingen, that's roughly November 24 to December 8. Transplant outdoors 1–2 weeks after your last frost.

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