Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 85172 — Stanfield, AZ

ZIP code 85172 (Stanfield, Pinal County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is February 5 and the first fall frost December 6.

Where ZIP 85172 is

Outlined: the ZIP code area · 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

Coldest night−6.7 to −3.9 °C

Last frostFeb 5

First frostDec 6

2012 zone9a

Same zone as on the 2012 map. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 9a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Stanfield, AZ…

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 Stanfield, AZ

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostFebruary 5median — 50% chance of a later frost

Safe for tender plantsFebruary 28only 10% chance of frost after

First fall frostDecember 6median — 10% chance by Nov 18

Growing season305 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 14 and returns around December 22.

From the NOAA station Casa Grande, AZ — 14 miles away, elevation 1,401 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 85172

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Dec 25 – Jan 8

SpinachSow outdoors · Dec 25 – Jan 15

Broccoli, cabbageStart indoors · Nov 27 – Dec 11

Broccoli, cabbageTransplant · Jan 15 – Jan 29

Onion setsPlant outdoors · Jan 8 – Jan 22

PotatoesPlant outdoors · Jan 15 – Jan 29

LettuceSow outdoors · Jan 8 – Jan 22

Carrots, beetsSow outdoors · Jan 15 – Jan 29

TomatoesStart indoors · Dec 11 – Dec 25

TomatoesTransplant · Feb 12 – Feb 26

Peppers, eggplantStart indoors · Nov 27 – Dec 11

Peppers, eggplantTransplant · Feb 19 – Mar 5

BeansSow outdoors · Feb 12 – Feb 26

Sweet cornSow outdoors · Feb 12 – Feb 26

Cucumbers, squashSow outdoors · Feb 12 – Feb 26

Fall lettuce, spinachSow outdoors · Oct 11 – Oct 25

GarlicPlant cloves · Nov 22 – Dec 27

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 5) and first fall frost (Dec 6) 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 85172 came on Jan 23 — 3 days earlier than the 1991–2020 average (Jan 26).

average
Jan 262026
Jan 23

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 Arizona

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

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 Stanfield, AZ.

Soil in Stanfield, AZ

The soil mapped at the center of ZIP 85172 is Contine — clay, well drained.

TextureClayholds water and nutrients; slow to drain and warm up

pH7.9alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter0.75%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Contine clay.

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 85172; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Stanfield, AZ

Summer high107 °Faverage high, July

Winter low38 °Faverage low, December

Hot days184days a year at 90 °F or more

Freezing nights17nights a year at 32 °F or less

Growing degree days8,266base 50 °F — the season’s usable heat

Longest day14 h 19 mindaylight on June 21

Shortest day9 h 59 mindaylight on December 21

Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully

Precipitation8.3 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Casa Grande, AZ (14 mi away); precipitation: Casa Grande 6.5 Nnw, AZ (11 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

1 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

851389a

Maricopa, AZ · 8 mi

851939a

Casa Grande, AZ · 9 mi

851229a

Casa Grande, AZ · 12 mi

851399a

Maricopa, AZ · 15 mi

851309a

Casa Grande, AZ · 16 mi

Casa Grande, AZ · 19 mi

Arizona planting zones →

Questions about 85172

What planting zone is ZIP code 85172?

ZIP code 85172 (Stanfield, AZ) is in USDA hardiness zone 9a on the 2023 map: the coldest night of an average winter reaches 20 to 25 °F (−6.7 to −3.9 °C).

When is the last frost in Stanfield, AZ?

The median last spring frost (32 °F) near 85172 is February 5; after February 28 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Casa Grande station.

When is the first frost in Stanfield, AZ?

The median first fall frost near 85172 is December 6, giving a median frost-free growing season of 305 days.

When should I plant tomatoes in 85172?

Start tomato seeds indoors around Dec 11 – Dec 25 and set transplants outside around Feb 12 – Feb 26, one to three weeks after the median last frost.

How much rain and snow does 85172 get?

About 8.3 inches of precipitation a year (NOAA 1991–2020 normals, Casa Grande 6.5 Nnw station).

How hot do summers get in Stanfield, AZ?

The average high peaks at 107 °F in July, with about 184 days a year at 90 °F or more.

What kind of soil does 85172 have?

The USDA soil survey maps Contine at the center of ZIP 85172: clay, well drained, pH about 7.9 (alkaline).

Did spring come early in Stanfield, AZ in 2026?

Spring leaf-out near 85172 came on Jan 23 in 2026, 3 days earlier than the 1991–2020 average (Jan 26), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Stanfield, AZ?

Intermediate onions: the longest day near 85172 is 14 h 19 min, so day-neutral types bulb best; long-day varieties may not bulb fully.