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

Planting zone for 85297 — Gilbert, AZ

ZIP code 85297 (Gilbert, Maricopa County) is in USDA zone 9b: the coldest winter night averages 25 to 30 °F. The median last spring frost is February 1 and the first fall frost December 11.

Where ZIP 85297 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.

Zone9b25 to 30 °F

Coldest night−3.9 to −1.1 °C

Last frostFeb 1

First frostDec 11

2012 zone9b

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 9b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Gilbert, 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 Gilbert, AZ

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostFebruary 1median — 50% chance of a later frost

Safe for tender plantsFebruary 27only 10% chance of frost after

First fall frostDecember 11median — 10% chance by Nov 23

Growing season315 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 8 and returns around December 26.

From the NOAA station Chandler Heights, AZ — 6 miles away, elevation 1,424 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 85297

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Dec 21 – Jan 4

SpinachSow outdoors · Dec 21 – Jan 11

Broccoli, cabbageStart indoors · Nov 23 – Dec 7

Broccoli, cabbageTransplant · Jan 11 – Jan 25

Onion setsPlant outdoors · Jan 4 – Jan 18

PotatoesPlant outdoors · Jan 11 – Jan 25

LettuceSow outdoors · Jan 4 – Jan 18

Carrots, beetsSow outdoors · Jan 11 – Jan 25

TomatoesStart indoors · Dec 7 – Dec 21

TomatoesTransplant · Feb 8 – Feb 22

Peppers, eggplantStart indoors · Nov 23 – Dec 7

Peppers, eggplantTransplant · Feb 15 – Mar 1

BeansSow outdoors · Feb 8 – Feb 22

Sweet cornSow outdoors · Feb 8 – Feb 22

Cucumbers, squashSow outdoors · Feb 8 – Feb 22

Fall lettuce, spinachSow outdoors · Oct 16 – Oct 30

GarlicPlant cloves · Nov 27 – Jan 1

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 1) and first fall frost (Dec 11) 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 85297 came on Jan 22 — 3 days earlier than the 1991–2020 average (Jan 25).

average
Jan 252026
Jan 22

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 9b in Arizona

499 plants native to the lower 48 states, recorded in Arizona, and rated by the USDA to survive 25 °F or colder — the bottom of zone 9b. 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 Gilbert, AZ.

Soil in Gilbert, AZ

The soil mapped at the center of ZIP 85297 is Mohall — loam, well drained.

TextureLoama good balance for most vegetables

pH8.2alkaline; 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: Mohall loam MLRA 40.

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 85297; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Gilbert, AZ

Summer high104 °Faverage high, July

Winter low39 °Faverage low, December

Hot days165days a year at 90 °F or more

Freezing nights11nights a year at 32 °F or less

Growing degree days7,921base 50 °F — the season’s usable heat

Longest day14 h 21 mindaylight on June 21

Shortest day9 h 57 mindaylight on December 21

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

Precipitation8.8 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: Chandler Heights, AZ (6 mi away); precipitation: Gilbert 3.9 Se, AZ (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 9b.

Chandler Heights, AZ · 5 mi

All 7 ZIP codes in Gilbert → · Arizona planting zones →

Questions about 85297

What planting zone is ZIP code 85297?

ZIP code 85297 (Gilbert, AZ) is in USDA hardiness zone 9b on the 2023 map: the coldest night of an average winter reaches 25 to 30 °F (−3.9 to −1.1 °C).

When is the last frost in Gilbert, AZ?

The median last spring frost (32 °F) near 85297 is February 1; after February 27 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Chandler Heights station.

When is the first frost in Gilbert, AZ?

The median first fall frost near 85297 is December 11, giving a median frost-free growing season of 315 days.

When should I plant tomatoes in 85297?

Start tomato seeds indoors around Dec 7 – Dec 21 and set transplants outside around Feb 8 – Feb 22, one to three weeks after the median last frost.

How much rain and snow does 85297 get?

About 8.8 inches of precipitation a year (NOAA 1991–2020 normals, Gilbert 3.9 Se station).

How hot do summers get in Gilbert, AZ?

The average high peaks at 104 °F in July, with about 165 days a year at 90 °F or more.

What kind of soil does 85297 have?

The USDA soil survey maps Mohall at the center of ZIP 85297: loam, well drained, pH about 8.2 (alkaline).

Did spring come early in Gilbert, AZ in 2026?

Spring leaf-out near 85297 came on Jan 22 in 2026, 3 days earlier than the 1991–2020 average (Jan 25), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Gilbert, AZ?

Intermediate onions: the longest day near 85297 is 14 h 21 min, so day-neutral types bulb best; long-day varieties may not bulb fully.