Kirby, 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.
On paper, artichoke, fig, california poppy, and cabbage all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Even in Kirby, 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 Kirby 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 Kirby — soil, climate, flood, and parcel records. How we handle your address.
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Kirby — the short answer
Kirby, Texas: USDA zone 9a, about 306 days between hard freezes, across 1K acres of city.
- USDA zone
- 9a
- USDA PHZM 2023
- Last hard freeze (28°F)
- Feb 6
- Bexar County normal — NOAA 1991–2020, nearest to this town
- First hard freeze (28°F)
- Dec 9
- Bexar County normal — NOAA 1991–2020, nearest to this town
- Days between freezes
- ~306
- Bexar County normal — NOAA 1991–2020, nearest to this town
- City area
- 1K 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 Bexar County’s — the closest measured record, labelled as such rather than passed off as local.
Hardiness Zone Range
Zone 9a is Kirby's average, not your lot's — a low corner or a tree line moves it. Against Kirby's 306-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Kirby
Each reading below is measured for Kirby itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
From county recordsKirby runs about 306 days between hard freezes (read from Bexar County, the closest normal to Kirby) — 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
MeasuredKirby 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 Kirby is in
Kirby sits in the Texas Blackland Prairies — EPA Level III, inside the wider Great Plains. That is read at Kirby's own centroid rather than borrowed from Bexar County.
What Grows in Kirby
Every plant below cleared Kirby's own zone 9a and its 306-day season. Each card opens that plant's Texas profile. How we score.
Is it too late to plant in Kirby?
Almost never — the real question is what to plant next. Cool-season crops can go in from around Jan 9; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 6 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Dec 9 — 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 Kirby
Survey cells within 31 miles of Kirby checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 660 miles off. What to watch for.
What's on the federal record near Kirby
Closest first, within ~10 miles of Kirby. Listing isn't leaking, and distance isn't exposure.
- WASTE OIL TANK SERVICEBrownfields · 1300 ft
- KIRBY CONVENIENCE STOREUnderground Storage Tanks · 1600 ft
- AY-68-37-608Nitrate · 1600 ft
- DIADEM FOOD MARTUnderground Storage Tanks · 2400 ft
- LONE STAR ICE & FOOD STORE 14Underground Storage Tanks · 2400 ft
- POLICE STATIONUnderground Storage Tanks · 2600 ft
- AY-68-37-304Nitrate · 0.5 mi
- ABC CONVENIENCE STOREUnderground Storage Tanks · 0.5 mi
- AY-68-37-602Nitrate · 0.5 mi
- AY-68-37-603Nitrate · 0.6 mi
- FAMILY DOLLAR #6169Brownfields · 0.7 mi
- KIRBY FOOD MARTUnderground Storage Tanks · 0.7 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Kirby'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 Kirby.
Sources Checked
within ~10 miles of Kirby
Severity Distribution
within ~10 miles of Kirby
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Kirby, Underground Storage Tanks runs higher than the national average — 1,877 sites within ~10 miles of Kirby. That's not a problem with your land — it's information about it.
Underground Storage Tanks: Underground storage tanks are the single most common source of soil contamination near homes and gardens.
Use raised beds with imported soil — this eliminates the primary soil-contact pathway.
Check your specific parcel in Kirby
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 Kirby average
Your land is one point inside Kirby
Everything above resolves to Kirby as a whole — one PHZM band, read across 1K acres, with hard-freeze dates borrowed from Bexar 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 Kirby Average
Kirby Average
- ●USDA Zones 9a, averaged across Kirby
- ●One soil character for all of Kirby
- ●Frost dates read at Kirby's scale: Feb 6 to Dec 9
YOUR Parcel
- ✓Your exact zone, not Kirby's 9a
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Kirby
Pull a site-specific report for your exact address in Kirby, Texas — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Kirby averages can't show:
We read public map data around Kirby — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Kirby average
How we know this about Kirby
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 Bexar 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 Kirby
When does frost risk typically end in Kirby?
The last hard freeze (28°F) in Kirby typically lands around Feb 6, 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 Feb 27.
When is the first frost in Kirby?
The first hard freeze (28°F) in Kirby typically arrives around Dec 9, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 25, so the watching starts about Nov 9 — about 306 days after the spring freeze cleared.
How long is the growing season in Kirby?
Measured between 28°F hard freezes, Kirby sees about 306 frost-free days — roughly Feb 6 through Dec 9, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Feb 27 to Nov 25, about 271 days.
Is the soil safe to grow vegetables in Kirby?
The federal record around Kirby runs heavier than most — 2,598 documented sites, mostly Underground Storage Tanks entries (1,877), the nearest Brownfields record about 0.2 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 Kirby?
From about Nov 9 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 9 (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 9. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Kirby's scale — its 9a band and its 306-day season. Your yard writes its own version of Kirby'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 Kirby’s own scale
6 of the readings below were taken at Kirby's own scale — the 1,280 acres it covers and 2,598 documented sites around it; 5 are borrowed from a wider read, named and linked below.
Measured here
- Kirby's own USDA hardiness band, zones 9aUSDA PHZM 2023
- 2,598 documented contamination sites on the federal record near Kirby, the closest Brownfields record about 0.2 miles out from the town centreFederal environmental registers
- Kirby's boundary and the 1,280 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 9a and a ~306-day seasonGrowable Ground crop-matching engine
- The ecoregion at Kirby's own centroid, the Texas Blackland PrairiesUS EPA Level III Ecoregions
- Lanternfly survey cells around Kirby checked, none carrying a detectionlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- The 28°F hard-freeze dates — Kirby has no normal of its own, so its county's is the closest measured readfrom Bexar County
- Soil character — no town-scale survey exists, so Kirby's 1,280 acres read through its county's SSURGO summaryfrom Bexar County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Bexar 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 Bexar County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Kirby's 1,280 acreswhy one lot differs from the next →
- Which side of Kirby you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 1,280 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Brownfields record about 0.2 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 Kirby-wide figureread your own land →
More in Texas
Wider growing context
What grows across TexasKirby sits outside our named growing regions, so Texas as a whole is its closest context here.
Nearby growing guides