Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated

Planting zone for Round Rock, TX

Round Rock, TX is in USDA zone 9a across its 6 ZIP codes. The median last spring frost is March 6 and the first fall frost November 24.

Round Rock on the zone map

Outlined: its 3 ZIP code areas · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zone9a20 to 25 °F
ZIP codes6
Last frostMar 6
First frostNov 24
Growing season259 days

9a 6 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Round Rock, TX…

Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Round Rock, TX

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 6median — 50% chance of a later frost
Safe for tender plantsMarch 30only 10% chance of frost after
First fall frostNovember 24median — 10% chance by Nov 5
Growing season259 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 23 and returns around December 5.

From the NOAA station Georgetown Lake, TX, elevation 873 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in Round Rock

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Jan 23 – Feb 6
SpinachSow outdoors · Jan 23 – Feb 13
Broccoli, cabbageStart indoors · Dec 26 – Jan 9
Broccoli, cabbageTransplant · Feb 13 – Feb 27
Onion setsPlant outdoors · Feb 6 – Feb 20
PotatoesPlant outdoors · Feb 13 – Feb 27
LettuceSow outdoors · Feb 6 – Feb 20
Carrots, beetsSow outdoors · Feb 13 – Feb 27
TomatoesStart indoors · Jan 9 – Jan 23
TomatoesTransplant · Mar 13 – Mar 27
Peppers, eggplantStart indoors · Dec 26 – Jan 9
Peppers, eggplantTransplant · Mar 20 – Apr 3
BeansSow outdoors · Mar 13 – Mar 27
Sweet cornSow outdoors · Mar 13 – Mar 27
Cucumbers, squashSow outdoors · Mar 13 – Mar 27
Fall lettuce, spinachSow outdoors · Sep 29 – Oct 13
GarlicPlant cloves · Nov 10 – Dec 15
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 6) and first fall frost (Nov 24) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 78665 came on Jan 29 — about the same time as the 1991–2020 average (Jan 28).

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Native plants for zone 9a in Texas

640 plants native to the lower 48 states, recorded in Texas, and rated by the USDA to survive 20 °F or colder — the bottom of zone 9a. Each links to its USDA PLANTS profile.

Trees 72

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °FArizona cypress50 ft · blooms spring · low shade tolerance · to −23 °FArizona walnut50 ft · blooms late spring · high shade tolerance · to −33 °F

Shrubs 141

alderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °Faloe yucca15 ft · blooms early summer · medium shade tolerance · to −1 °FAmerican beautyberry6 ft · blooms early summer · medium shade tolerance · to −8 °FAmerican holly40 ft · blooms mid spring · low shade tolerance · to −20 °FAmerican hornbeam30 ft · blooms mid spring · low shade tolerance · to −34 °FAmerican snowbell10 ft · blooms spring · medium shade tolerance · to −16 °F

Wildflowers & perennials 208

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine mountainsorrel1 ft · blooms mid summer · medium shade tolerance · to −43 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican century plant6 ft · blooms indeterminate · high shade tolerance · to 12 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °F

Grasses 196

alkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °FAmerican cupscale3 ft · blooms early summer · high shade tolerance · to −18 °FArizona cottontop4 ft · blooms late summer · high shade tolerance · to −13 °FArizona fescue2 ft · blooms late spring · high shade tolerance · to −23 °FArizona threeawn2 ft · blooms mid summer · high shade tolerance · to −3 °Fautumn bluegrass1.5 ft · blooms late spring · medium shade tolerance · to −8 °F

Vines 14

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °FAmerican wisteria50 ft · blooms spring · low shade tolerance · to −3 °Fcatbird grape30 ft · blooms late spring · medium shade tolerance · to −13 °Fcupseed30 ft · blooms late spring · low shade tolerance · to −3 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °F

Source: USDA, NRCS. 2026. The PLANTS Database (plants.usda.gov), National Plant Data Team — state distribution, native status and the “Temperature, Minimum” characteristic. Check light, moisture and soil needs before buying; local nurseries and your state native plant society can confirm what thrives in Round Rock, TX.

Soil in Round Rock, TX

The soil mapped at the center of ZIP 78665 is Castephen — silty clay, well drained.

TextureSilty clayholds water and nutrients; slow to drain and warm up
pH8.2alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2.5%moderate
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Castephen silty clay, 1 to 3 percent slopes.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 78665; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Round Rock, TX

Summer high97 °Faverage high, August
Winter low36 °Faverage low, January
Hot days112days a year at 90 °F or more
Freezing nights28nights a year at 32 °F or less
Growing degree days6,670base 50 °F — the season’s usable heat
Longest day14 h 08 mindaylight on June 21
Shortest day10 h 10 mindaylight on December 21
Onions to growShort-daysummer days stay under about 14 h 20 min, so long-day varieties won’t bulb
Precipitation34.3 inper year, rain and melted snow

Average high and low, by month

30°40°50°60°70°80°90°100°110°32 °FJanuary: average high 60 °F, low 36 °F 60°36° JanFebruary: average high 65 °F, low 40 °F 65°40° FebMarch: average high 72 °F, low 47 °F 72°47° MarApril: average high 79 °F, low 54 °F 79°54° AprMay: average high 85 °F, low 63 °F 85°63° MayJune: average high 92 °F, low 70 °F 92°70° JunJuly: average high 96 °F, low 72 °F 96°72° JulAugust: average high 97 °F, low 72 °F 97°72° AugSeptember: average high 90 °F, low 67 °F 90°67° SepOctober: average high 81 °F, low 57 °F 81°57° OctNovember: average high 70 °F, low 46 °F 70°46° NovDecember: average high 62 °F, low 38 °F 62°38° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 2.67 in precipitation 2.7 JanFebruary: 2.02 in precipitation 2.0 FebMarch: 3.15 in precipitation 3.1 MarApril: 1.97 in precipitation 2.0 AprMay: 4.33 in precipitation 4.3 MayJune: 3.43 in precipitation 3.4 JunJuly: 2.33 in precipitation 2.3 JulAugust: 2.73 in precipitation 2.7 AugSeptember: 3.46 in precipitation 3.5 SepOctober: 2.87 in precipitation 2.9 OctNovember: 2.78 in precipitation 2.8 NovDecember: 2.59 in precipitation 2.6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Georgetown Lake, TX (10 mi away); precipitation: Round Rock 3.0 Ne, TX (within 1 mile). Daylight is calculated from latitude.

ZIP codes in Round Rock

786649a
20 to 25 °F
786659a
20 to 25 °F
786809a
20 to 25 °F
786819a
20 to 25 °F
786829a
20 to 25 °F
786839a
20 to 25 °F

Texas planting zones →

Questions about Round Rock

What planting zone is Round Rock, TX?

Round Rock, TX is in USDA hardiness zone 9a on the 2023 map (9a: 20 to 25 °F).

When is the last frost in Round Rock, TX?

The median last spring frost is March 6 and the median first fall frost is November 24 (NOAA 1991–2020 normals, Georgetown Lake station).

When can I plant a garden in Round Rock, TX?

Cool-season crops like peas and spinach go in around Jan 23 – Feb 13; tomatoes, peppers, beans and squash after about Mar 13, once frost risk has passed.

What kind of onions grow in Round Rock, TX?

Short-day onions: the longest day is 14 h 08 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.

How much rain and snow does Round Rock, TX get?

About 34.3 inches of precipitation a year (NOAA 1991–2020 normals).