Pima County, in Arizona, sits in USDA hardiness zone 9a — a zone band wide enough that plant choice, not possibility, is the interesting question.
On paper, palo verde, citrus, jalapeno, and date palm all suit these conditions — on the ground, soil, sun, and drainage make the final call.
Pima County lies within the Sonoran Desert — a regional growing area with its own character.
Grounded in USDA PHZM 2023 · Growable Ground suitability scoring
Pima County holds more than one microclimate.
Soils and elevations shift across Pima County, so your frost dates and drainage aren't the county average. Enter your address and we'll score 1,112 plants against your land's actual soil, sun, and frost.
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
No card required · your full report in seconds
Quick Facts
USDA Zones
9a
Last Frost (state avg.)
Jan 15 - May 1
First Frost (state avg.)
Oct 15 - Dec 15
County Area
5.9M acres
Hardiness Zone Range
Growing Season
Zone maps are averages across Pima County. Your yard's slope, trees, and frost pockets shift what actually grows — see your land's exact reading.
Soil in Pima County
Across Pima County, the ground is predominantly Aridisols, where Mohall, Hayhook, and Bucklebar are the most extensive named soil series. The soil is generally well drained with a sandy loam surface. Topsoil pH runs about 7.2–7.9, slightly alkaline. Rainfall drains through hydrologic group D soils.
Soil order
Aridisols
Drainage
Well drained
Hydric soils
0%
Soil still varies lot by lot — soil types explained.
What Grows in Pima County
Plants matched to Pima County's USDA zones 9a — each links to its full growing profile.
Growing Challenges in Arizona
What an experienced grower plans around here — each one has a move.
Extreme heat exceeding 110F stresses most plants
Desert gardens run on winter: plant to the October-March windows and give the summer holdouts afternoon shade.
Minimal rainfall requires drip irrigation
Drip plus a deep mulch layer is the desert baseline — it waters roots, not air, and cuts evaporation dramatically.
Caliche hardpan prevents root penetration without breaking through
Where caliche won't break, build up instead — a deep raised bed gives roots the depth the ground refuses.
For cultivar selection, pest pressure, and planting-time guidance specific to Arizona, the University of Arizona Cooperative Extension is the authoritative local source.
Safe to Grow Here?
What the federal record shows across Pima County — and how to grow with it.
We checked the federal record across Pima County — 5,043 documented sites across 7 of the 9 source types we track.
The most significant on record: 22 Superfund sites. Sites tracked in EPA's Superfund program — from assessment-stage CERCLIS entries to confirmed National Priorities List cleanup sites.
Pima County carries one of the heavier federal records we track — and that's not a verdict on your yard. Proximity to a documented site is information, not a diagnosis: nothing here says any particular parcel is affected. It does earn one concrete step — before food beds go in the ground, a professional soil test tells you exactly what you're working with, and raised beds with clean imported soil grow well almost anywhere in the meantime.
Sources: EPA, USGS — 1.8M documented sites tracked nationwide across 9 federal source types.
Environmental Intelligence
Understanding what's nearby helps you make informed decisions about where and how to grow.
Severity Distribution
across Pima County
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Pima County, two things run higher than the national average — Mining (1,285 sites) and Nitrate (1,588 sites). That's not a problem with your land — it's information about it.
Mining: Mining sites — both historic and active — can leach heavy metals (arsenic, lead, cadmium, mercury) into soil and water for centuries after operations cease.
Nitrate: Nitrate contamination primarily comes from agricultural fertilizer runoff and failing septic systems.
Test soil for heavy metals (lead, arsenic, cadmium, mercury) — this is essential near any mining site.
Test well water for nitrate if you rely on a private well for irrigation (EPA standard: 10 mg/L).
Check your specific parcel in Pima County
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,112 plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Your Specific Parcel Matters
Pima County Average
- ●USDA Zones 9a
- ●Generic soil type for the area
- ●State-average frost dates
YOUR Parcel
- ✓Your exact hardiness zone
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your parcel in Pima County
Pull a site-specific report for your exact address in Pima County, Arizona — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your exact spot that zone averages miss:
We read public map data for this spot — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources analyzed in seconds
Key Growing Facts for Pima County, Arizona
- USDA Hardiness Zones: 9a (USDA PHZM 2023)
- Last Spring Frost (state avg.): Jan 15 - May 1 (NOAA 30-Year Climate Normals)
- First Fall Frost (state avg.): Oct 15 - Dec 15 (NOAA 30-Year Climate Normals)
- County Land Area: 5.9M acres (US Census TIGER 2025)
Zone data: USDA ARS Plant Hardiness Zone Map 2023. Climate data: NOAA NCEI. County boundaries: US Census TIGER/Line 2025.
Frost dates here are the Pima County average. Low spots and tree cover move them by days on any one yard — see your exact frost windows.
Frequently Asked Questions
What hardiness zone is Pima County, Arizona?
Pima County sits in USDA hardiness zone 9a, per the USDA Plant Hardiness Zone Map 2023. Zones reflect average annual extreme minimum temperatures from 1991–2020 weather data.
When does frost risk typically end in Pima County?
Pima County follows Arizona's statewide frost window: last spring frost around Jan 15 - May 1 and first fall frost around Oct 15 - Dec 15, per NOAA 30-year climate normals (1991–2020). Frost dates shift with elevation and local microclimate, so watch your own site's cold pockets.
What vegetables grow in Pima County?
Pima County's zone 9a supports a wide range — strong performers include Palo Verde, Citrus, Jalapeno, Date Palm, and Prickly Pear. What actually takes on any one site comes down to its soil, sun, and drainage, and we score each plant against the real conditions at your address.
Which hardiness zone is Pima County, really?
Officially, Pima County sits in USDA zone 9a (USDA PHZM 2023) — but a zone is a 30-year average of winter's coldest night across an area, and it can't see any one yard. A south-facing slope, a tree line, or a low frost pocket can shift a single site by half a zone either way, which is why neighboring gardeners often quote different numbers. We read the conditions at your exact address — soil, sun, slope, and frost — and score 1,112 plants against what's actually there.
Is the soil safe to grow vegetables in Pima County?
The federal record around Pima County runs heavier than most — 5,043 documented sites — 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.
Just moved to Pima County — what should I know before planting?
Start with three facts. Pima County sits in USDA zone 9a, which sets what survives winter; the statewide frost window runs about Jan 15 - May 1 to Oct 15 - Dec 15 (NOAA 30-year climate normals); and 5,043 documented sites sit on the federal record here, so a soil test before food beds is the smart first step. From there, matching plants to your actual soil and sun is the fun part.
Everything on this page is a Pima County average. Your yard writes its own version — we read soil, sun, drainage, and frost at your exact address. Try it for 14 days — no card required.
Will It Grow Here?
Zone fit is the first question — each answer below reads Arizona's frost window, season length, and soil profile against the plant's real requirements.