Fort Thomas, Arizona, sits in USDA hardiness zone 8b — a range where zone-matched perennials and frost-aware annual timing set what succeeds.
On paper, cabbage, fig, california poppy, and collard greens all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Even in Fort Thomas, 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 Fort Thomas 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 Fort Thomas — soil, climate, flood, and parcel records. How we handle your address.
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Fort Thomas — the short answer
Fort Thomas, Arizona: USDA zone 8b, about 266 days between hard freezes, across 6K acres of town.
- USDA zone
- 8b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Feb 27
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 20
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~266
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Town area
- 6K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 8b is Fort Thomas's average, not your lot's — a low corner or a tree line moves it. Against Fort Thomas's 266-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Fort Thomas
Each reading below is measured for Fort Thomas itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredFort Thomas runs about 266 days between hard freezes — 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
MeasuredFort Thomas sits in USDA hardiness zone 8b.
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 Fort Thomas is in
Fort Thomas sits in the Chihuahuan Deserts — EPA Level III, inside the wider North American Deserts. That is read at Fort Thomas's own centroid, and it is not what its county reads: Graham County is mostly Madrean Archipelago. The wider page above you is answering a different question about different ground.
What Grows in Fort Thomas
Every plant below cleared Fort Thomas's own zone 8b and its 266-day season. Each card opens that plant's Arizona profile. How we score.
Is it too late to plant in Fort Thomas?
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 30; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Feb 27 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 20 — 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 Fort Thomas
Survey cells within 31 miles of Fort Thomas checked for spotted lanternfly, none carrying a detection — a surveyed negative, not an absence of looking. Nearest documented record 418 miles off. What to watch for.
What's on the federal record near Fort Thomas
Closest first, within ~10 miles of Fort Thomas. Listing isn't leaking, and distance isn't exposure.
- D-05-23 02ACNitrate · 1300 ft
- D-05-23 02CBB1Nitrate · 2200 ft
- D-04-23 35CC 2Nitrate · 2300 ft
- KEENS FORT THOMAS STOREUnderground Storage Tanks · 2400 ft
- D-05-23 02CDNitrate · 0.6 mi
- D-05-23 03DCCNitrate · 1.0 mi
- D-05-23 01DCCNitrate · 1.4 mi
- D-04-23 27CCC2Nitrate · 1.9 mi
- D-04-23 28CDCNitrate · 2.4 mi
- FAA PIMA RMLRUnderground Storage Tanks · 2.7 mi
- D-04-23 29ADCNitrate · 3.1 mi
- D-05-24 18ADNitrate · 3.4 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Fort Thomas'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 Fort Thomas.
Total Sites
90
within ~10 miles of Fort Thomas
Risk Level
Moderate
Highest-severity
1 mining site (prospects, none worked)
Sources Checked
within ~10 miles of Fort Thomas
Severity Distribution
within ~10 miles of Fort Thomas
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Fort Thomas, Nitrate runs higher than the national average — 86 sites within ~10 miles of Fort Thomas. It's not cause for alarm — it's worth knowing, and there's a sensible way to grow around it.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Fort Thomas
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 Fort Thomas average
Your land is one point inside Fort Thomas
Everything above resolves to Fort Thomas as a whole — one PHZM band and one 28°F frost record, read across 6K acres. 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 town 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 Fort Thomas Average
Fort Thomas Average
- ●USDA Zones 8b, averaged across Fort Thomas
- ●One soil character for all of Fort Thomas
- ●Frost dates read at Fort Thomas's scale: Feb 27 to Nov 20
YOUR Parcel
- ✓Your exact zone, not Fort Thomas's 8b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Fort Thomas
Pull a site-specific report for your exact address in Fort Thomas, Arizona — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Fort Thomas averages can't show:
We read public map data around Fort Thomas — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Fort Thomas average
How we know this about Fort Thomas
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this town’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Fort Thomas’s own record; 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 town grain anywhere on this page — there is no town-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 Fort Thomas
When does frost risk typically end in Fort Thomas?
The last hard freeze (28°F) in Fort Thomas typically lands around Feb 27, 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 20.
When is the first frost in Fort Thomas?
The first hard freeze (28°F) in Fort Thomas typically arrives around Nov 20, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Nov 6, so the watching starts about Oct 21 — about 266 days after the spring freeze cleared.
How long is the growing season in Fort Thomas?
Measured between 28°F hard freezes, Fort Thomas sees about 266 frost-free days — roughly Feb 27 through Nov 20, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Mar 20 to Nov 6, about 231 days.
Is the soil safe to grow vegetables in Fort Thomas?
The federal record around Fort Thomas shows 90 documented sites, mostly Nitrate entries (86), the nearest Nitrate record about 0.2 miles out — a typical footprint for a growing area, and proximity to a documented site is information, not a diagnosis of any one yard. It's worth seeing which recorded sites sit closest to where you grow, and testing the soil before new food beds near any of them.
How do I protect my plants from frost in Fort Thomas?
From about Oct 21 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 Nov 20 (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 Nov 20. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Fort Thomas's scale — its 8b band and its 266-day season. Your yard writes its own version of Fort Thomas'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 Fort Thomas’s own scale
7 of the readings below were taken at Fort Thomas's own scale — its own ~266-day season between 28°F freezes, the 5,549 acres it covers and 90 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Fort Thomas's own USDA hardiness band, zones 8bUSDA PHZM 2023
- Fort Thomas's own 28°F hard-freeze dates, about Feb 27 and Nov 20 and the ~266-day span between themNOAA 1991–2020 Climate Normals
- 90 documented contamination sites on the federal record near Fort Thomas, the closest Nitrate record about 0.2 miles out from the town centreFederal environmental registers
- Fort Thomas's boundary and the 5,549 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 8b and a ~266-day seasonGrowable Ground crop-matching engine
- Fort Thomas sits in the Chihuahuan Deserts — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
- Lanternfly survey cells around Fort Thomas checked, none carrying a detectionlydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Fort Thomas's 5,549 acres read through its county's SSURGO summaryfrom Graham County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Graham County
- The growing challenges every Arizona grower plans around — written at state scale, so they stay on the state guidefrom Arizona
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Graham County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Fort Thomas's 5,549 acreswhy one lot differs from the next →
- Which side of Fort Thomas you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 5,549 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Nitrate 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 Fort Thomas-wide figureread your own land →
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