Round Rock, Texas, sits in USDA hardiness zone 9a — enough range to grow cool-season vegetables, hardy fruit, and warm-season crops that mature before the first hard frost.
Among the crops suited to this profile: artichoke, fig, california poppy, and cabbage. The site-level story — soil, sun, drainage — decides the rest.
Even in Round Rock, no two yards are alike.
A low spot, a south-facing slope, or a stand of trees moves the frost date and sun across a single Round Rock lot. Enter your address and we'll score 1,086 plants against your land's actual soil, sun, and frost.
We read public map data around Round Rock — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Round Rock — the short answer
Round Rock, Texas: USDA zone 9a, about 292 days between hard freezes, across 24K acres of city.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Feb 13
- Williamson County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 2
- Williamson County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~292
- Williamson County normal — NOAA 1991–2020, nearest to this town
- City area
- 24K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. No 30-year normal resolves at this town’s own centroid, so the hard-freeze dates are Williamson County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9a is Round Rock's average, not your lot's — a low corner or a tree line moves it. Against Round Rock's 292-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Round Rock
Each reading below is measured for Round Rock itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsRound Rock runs about 292 days between hard freezes (read from Williamson County, the closest normal to Round Rock) — close to year-round growing.
Frost is rarely the limit here; winter plantings are as real as summer ones, and the harder question is which crops shrug off the summer heat.
Grow cool-season crops through the mild winter, and choose heat-tolerant varieties for the summer beds.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredRound Rock sits in USDA hardiness zone 9a.
The zone sets which perennials, shrubs, and fruit trees live through an average winter here — a plant rated for a colder zone is a safe bet, one rated warmer needs winter protection or gets treated as an annual.
Match perennials and fruit to the zone before you buy, so nothing you plant is a gamble against the cold.
USDA PHZM 2023
The kind of country Round Rock is in
Round Rock sits in the Texas Blackland Prairies — EPA Level III, inside the wider Great Plains. That is read at Round Rock's own centroid rather than borrowed from Williamson County.
What Grows in Round Rock
Every plant below cleared Round Rock's own zone 9a and its 292-day season. Each card opens that plant's Texas profile. How we score.
Is it too late to plant in Round Rock?
Too late for some crops, right on time for others — a growing season is a sequence, not a deadline. Cool-season crops can go in from around Jan 16; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 13 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 2 — long-season crops need about 90 days of runway, quick greens only 30. And with a calendar this mild, the honest answer is that planting barely stops — winter opens seasons colder regions never see.
Documented around Round Rock
Survey cells within 31 miles of Round Rock checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 611 miles off. What to watch for.
What's on the federal record near Round Rock
Closest first, within ~10 miles of Round Rock. Listing isn't leaking, and distance isn't exposure.
- 7-ELEVEN STORE 36647Underground Storage Tanks · 0.6 mi
- Q & Q MARTUnderground Storage Tanks · 0.6 mi
- 7-ELEVEN 25391Underground Storage Tanks · 0.6 mi
- PALM VALLEY FOODMARTUnderground Storage Tanks · 0.6 mi
- HEB 591Underground Storage Tanks · 0.7 mi
- WAG-A-BAG 1Underground Storage Tanks · 0.7 mi
- CONSOLIDATED METAL TECHNOLOGIESBrownfields · 0.8 mi
- WAG-A-BAG 14Underground Storage Tanks · 0.9 mi
- MURPHY EXPRESS 8649Underground Storage Tanks · 0.9 mi
- WAG-A-BAG 7Underground Storage Tanks · 0.9 mi
- ZK-58-27-610Nitrate · 1.1 mi
- ROUND ROCK SERVICE CENTERUnderground Storage Tanks · 1.2 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Round Rock's center, not your beds. Run your own address for what's upwind of you specifically.
Environmental Intelligence
The counts behind that headline — every source type on the record near Round Rock.
Total Sites
788
within ~10 miles of Round Rock
Risk Level
High
Highest-severity
1 Superfund site (none NPL-listed)
Sources Checked
within ~10 miles of Round Rock
Severity Distribution
within ~10 miles of Round Rock
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Round Rock, two things run higher than the national average within ~10 miles of Round Rock — PFAS (19 sites) and Toxics Release Inventory (59 sites). It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
PFAS: PFAS (per- and polyfluoroalkyl substances) are called "forever chemicals" because they do not biodegrade.
Toxics Release Inventory: TRI facilities report annual chemical releases to air, water, and land.
Test irrigation water source — this is the primary pathway for PFAS to reach garden crops.
Check prevailing wind direction — downwind parcels face higher exposure than upwind or crosswind locations.
Check your specific parcel in Round Rock
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,086 plant recommendations.
25+ data sources read at your address, not the Round Rock average
Your land is one point inside Round Rock
Everything above resolves to Round Rock as a whole — one PHZM band, read across 24K acres, with hard-freeze dates borrowed from Williamson County’s record because no 30-year normal resolves at this city’s own centroid. Your parcel is one point inside that footprint. Slope, tree cover, a low spot that pools cold air, and what is in the soil are all resolved at the address, and none of them are visible at city scale. That is the honest boundary of this page, and the reason the next step is a reading of your own ground rather than a better local average.
Your Lot vs the Round Rock Average
Round Rock Average
- ●USDA Zones 9a, averaged across Round Rock
- ●One soil character for all of Round Rock
- ●Frost dates read at Round Rock's scale: Feb 13 to Dec 2
YOUR Parcel
- ✓Your exact zone, not Round Rock's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Round Rock
Pull a site-specific report for your exact address in Round Rock, Texas — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Round Rock averages can't show:
We read public map data around Round Rock — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Round Rock average
How we know this about Round Rock
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Williamson County’s record, because none resolves here; boundaries and acreage from US Census TIGER/Line 2025; the contamination records from the federal sources named in their beats above. Soil is not read at city grain anywhere on this page — there is no city-resolution survey in our data, which is why you will find no soil grid here rather than a statewide one wearing a local label. The resolution ledger below names every figure this page inherited.
Common questions about Round Rock
When does frost risk typically end in Round Rock?
The last hard freeze (28°F) in Round Rock typically lands around Feb 13, per NOAA 1991–2020 climate normals — earlier than the light-frost dates most charts quote. That marks the hard freeze, not the last light frost — lighter frosts keep biting past it, which is why tender transplants here wait until about Mar 6.
When is the first frost in Round Rock?
The first hard freeze (28°F) in Round Rock typically arrives around Dec 2, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 18, so the watching starts about Nov 2 — about 292 days after the spring freeze cleared.
How long is the growing season in Round Rock?
Measured between 28°F hard freezes, Round Rock sees about 292 frost-free days — roughly Feb 13 through Dec 2, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Mar 6 to Nov 18, about 257 days.
Is the soil safe to grow vegetables in Round Rock?
The federal record around Round Rock runs heavier than most — 788 documented sites, mostly Underground Storage Tanks entries (460), the nearest Underground Storage Tanks record about 0.6 miles out — so test the soil before planting food in the ground, and raised beds with clean imported soil grow well in the meantime. Even here, proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what's recorded and where.
How do I protect my plants from frost in Round Rock?
From about Nov 2 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Dec 2 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Dec 2. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Round Rock's scale — its 9a band and its 292-day season. Your yard writes its own version of Round Rock's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
What this page reads at Round Rock’s own scale
6 of the readings below were taken at Round Rock's own scale — the 24,408 acres it covers and 788 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Round Rock's own USDA hardiness band, zones 9aUSDA PHZM 2023
- 788 documented contamination sites on the federal record near Round Rock, the closest Underground Storage Tanks record about 0.6 miles out from the town centreFederal environmental registers
- Round Rock's boundary and the 24,408 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~292-day seasonGrowable Ground crop-matching engine
- The ecoregion at Round Rock's own centroid, the Texas Blackland PrairiesUS EPA Level III Ecoregions
- Lanternfly survey cells around Round Rock checked, none carrying a detectionlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- The 28°F hard-freeze dates — Round Rock has no normal of its own, so its county's is the closest measured readfrom Williamson County
- Soil character — no town-scale survey exists, so Round Rock's 24,408 acres read through its county's SSURGO summaryfrom Williamson County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Williamson County
- The growing challenges every Texas grower plans around — written at state scale, so they stay on the state guidefrom Texas
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Williamson County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Round Rock's 24,408 acreswhy one lot differs from the next →
- Which side of Round Rock you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 24,408 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.6 miles out, measured from the town centrehow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — measured at your address, and averaged away by any Round Rock-wide figureread your own land →
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