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

Planting zone for 85390 — Wickenburg, AZ

ZIP code 85390 (Wickenburg, Maricopa County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is March 7 and the first fall frost November 20.

Where ZIP 85390 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 frostMar 7

First frostNov 20

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 Wickenburg, 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 Wickenburg, AZ

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMarch 7median — 50% chance of a later frost

Safe for tender plantsApril 8only 10% chance of frost after

First fall frostNovember 20median — 10% chance by Nov 4

Growing season254 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 14 and returns around December 2.

From the NOAA station Wickenburg, AZ — 9 miles away, elevation 2,097 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 85390

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Jan 24 – Feb 7

SpinachSow outdoors · Jan 24 – Feb 14

Broccoli, cabbageStart indoors · Dec 27 – Jan 10

Broccoli, cabbageTransplant · Feb 14 – Feb 28

Onion setsPlant outdoors · Feb 7 – Feb 21

PotatoesPlant outdoors · Feb 14 – Feb 28

LettuceSow outdoors · Feb 7 – Feb 21

Carrots, beetsSow outdoors · Feb 14 – Feb 28

TomatoesStart indoors · Jan 10 – Jan 24

TomatoesTransplant · Mar 14 – Mar 28

Peppers, eggplantStart indoors · Dec 27 – Jan 10

Peppers, eggplantTransplant · Mar 21 – Apr 4

BeansSow outdoors · Mar 14 – Mar 28

Sweet cornSow outdoors · Mar 14 – Mar 28

Cucumbers, squashSow outdoors · Mar 14 – Mar 28

Fall lettuce, spinachSow outdoors · Sep 25 – Oct 9

GarlicPlant cloves · Nov 6 – Dec 11

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 7) and first fall frost (Nov 20) 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 85390 came on Jan 21 — 6 days earlier than the 1991–2020 average (Jan 27).

average
Jan 272026
Jan 21

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 Wickenburg, AZ.

Soil in Wickenburg, AZ

The soil mapped at the center of ZIP 85390 is Gran — very gravelly sandy loam, well drained.

TextureVery gravelly sandy loamdrains and warms fast; dries out and needs more feeding

pH7.9alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter0.75%low — add compost

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Gran-Wickenburg complex, low precipitation, 1 to 10 percent slopes.

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 85390; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Wickenburg, AZ

Summer high104 °Faverage high, July

Winter low33 °Faverage low, December

Hot days162days a year at 90 °F or more

Freezing nights47nights a year at 32 °F or less

Growing degree days6,532base 50 °F — the season’s usable heat

Longest day14 h 25 mindaylight on June 21

Shortest day9 h 54 mindaylight on December 21

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

Precipitation10.9 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: Wickenburg, AZ (9 mi away); precipitation: Wickenburg, AZ (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

853589a

Wickenburg, AZ · 10 mi

Morristown, AZ · 24 mi

All 2 ZIP codes in Wickenburg → · Arizona planting zones →

Questions about 85390

What planting zone is ZIP code 85390?

ZIP code 85390 (Wickenburg, 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 Wickenburg, AZ?

The median last spring frost (32 °F) near 85390 is March 7; after April 8 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Wickenburg station.

When is the first frost in Wickenburg, AZ?

The median first fall frost near 85390 is November 20, giving a median frost-free growing season of 254 days.

When should I plant tomatoes in 85390?

Start tomato seeds indoors around Jan 10 – Jan 24 and set transplants outside around Mar 14 – Mar 28, one to three weeks after the median last frost.

How much rain and snow does 85390 get?

About 10.9 inches of precipitation a year (NOAA 1991–2020 normals, Wickenburg station).

How hot do summers get in Wickenburg, AZ?

The average high peaks at 104 °F in July, with about 162 days a year at 90 °F or more.

What kind of soil does 85390 have?

The USDA soil survey maps Gran at the center of ZIP 85390: very gravelly sandy loam, well drained, pH about 7.9 (alkaline).

Did spring come early in Wickenburg, AZ in 2026?

Spring leaf-out near 85390 came on Jan 21 in 2026, 6 days earlier than the 1991–2020 average (Jan 27), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Wickenburg, AZ?

Intermediate onions: the longest day near 85390 is 14 h 25 min, so day-neutral types bulb best; long-day varieties may not bulb fully.