Frost Dates for Round Rock, TX 78664

Round Rock has 3 ZIP codes. The Round Rock, TX frost page lists all of them with their dates.

Last spring frost February 24 · First fall frost November 28 · 277 frost-free days · USDA Zone 9a

Frost probability for 78664

Frost10%50%90%
Spring (last frost)March 20February 24February 1
Fall (first frost)November 7November 28December 19

Dates come from NOAA 1971–2000 freeze probabilities at the nearest reporting station (30.7 km away); the 50% date is the median year.

Month by month in Round Rock

MonthWhat to do
JanuaryStart herbs, basil, and squash indoors (4–6 weeks before frost). Direct sow peas, spinach, and lettuce if soil is workable.
FebruaryLast frost around February 24. Transplant cold-hardy crops (broccoli, kale, cabbage). Harden off tomato and pepper seedlings.
MarchFrost has passed. Transplant tomatoes, peppers, and basil outdoors. Direct sow beans, cucumbers, squash, and zucchini.
AprilSuccession plant lettuce and greens. Keep beds weeded and watered consistently.
MayHarvest regularly to encourage production. Monitor for pests and disease.
JuneMidsummer: harvest beans, zucchini, cucumbers. Start brassica seeds indoors for fall.
JulyDirect sow carrots and beets for fall harvest. Start fall broccoli and kale indoors.
AugustDirect sow carrots and beets for fall harvest. Start fall broccoli and kale indoors.
SeptemberDirect sow carrots and beets for fall harvest. Start fall broccoli and kale indoors.
OctoberFirst fall frost approaching (around November 28). Transplant fall brassicas. Sow spinach, arugula, and radishes.
NovemberFirst frost around November 28. Harvest tomatoes and peppers before frost. Cover cold-hardy crops with row covers to extend the season.
DecemberHarvest remaining cold-hardy crops: kale, carrots, and beets. Plant garlic bulbs for next year.

What grows in a 277-day season

Frequently Asked Questions

What is the last frost date for Round Rock, TX (ZIP 78664)?

The median last spring frost date for Round Rock, TX (ZIP code 78664) is around February 24. 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 Round Rock, TX?

The median first fall frost date for Round Rock, TX is around November 28. 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 Round Rock, TX?

The frost-free growing season in Round Rock is about 277 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 Round Rock, TX?

Based on frost date patterns, Round Rock falls approximately in 9a. 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 Round Rock, TX?

Start tomato seeds indoors 6–8 weeks before your last frost date (around February 24). For Round Rock, that's roughly December 30 to January 13. Transplant outdoors 1–2 weeks after your last frost.

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