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

Planting zone for 85652 — Cortaro, AZ

ZIP code 85652 (Cortaro, Pima County) is in USDA zone 9b: the coldest winter night averages 25 to 30 °F. The median last spring frost is February 26 and the first fall frost December 4.

Where ZIP 85652 is

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 26

First frostDec 4

2012 zone9a

Was 9a on the 2012 map — half a zone warmer now. 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 Cortaro, 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 Cortaro, AZ

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostFebruary 26median — 50% chance of a later frost

Safe for tender plantsMarch 18only 10% chance of frost after

First fall frostDecember 4median — 10% chance by Nov 17

Growing season279 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 1 and returns around December 17.

From the NOAA station Tohono Chul, AZ — 9 miles away, elevation 2,526 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 85652

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Jan 15 – Jan 29

SpinachSow outdoors · Jan 15 – Feb 5

Broccoli, cabbageStart indoors · Dec 18 – Jan 1

Broccoli, cabbageTransplant · Feb 5 – Feb 19

Onion setsPlant outdoors · Jan 29 – Feb 12

PotatoesPlant outdoors · Feb 5 – Feb 19

LettuceSow outdoors · Jan 29 – Feb 12

Carrots, beetsSow outdoors · Feb 5 – Feb 19

TomatoesStart indoors · Jan 1 – Jan 15

TomatoesTransplant · Mar 5 – Mar 19

Peppers, eggplantStart indoors · Dec 18 – Jan 1

Peppers, eggplantTransplant · Mar 12 – Mar 26

BeansSow outdoors · Mar 5 – Mar 19

Sweet cornSow outdoors · Mar 5 – Mar 19

Cucumbers, squashSow outdoors · Mar 5 – Mar 19

Fall lettuce, spinachSow outdoors · Oct 9 – Oct 23

GarlicPlant cloves · Nov 20 – Dec 25

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 26) and first fall frost (Dec 4) 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 85652 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 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 Cortaro, AZ.

Soil in Cortaro, AZ

The soil mapped at the center of ZIP 85652 is Anthony — gravelly sandy loam, well drained.

TextureGravelly 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 matter0.5%low — add compost

Hydrologic groupAwater soaks in fast

Farmland classPrime farmland if irrigated and either protected from flooding or not frequently flooded during the growing seasonUSDA classification

Map unit: Anthony gravelly sandy loam,1 to 3 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 85652; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Cortaro, AZ

Summer high102 °Faverage high, June

Winter low37 °Faverage low, January

Hot days159days a year at 90 °F or more

Freezing nights20nights a year at 32 °F or less

Growing degree days7,240base 50 °F — the season’s usable heat

Longest day14 h 17 mindaylight on June 21

Shortest day10 h 01 mindaylight on December 21

Onions to growShort-daysummer days stay under about 14 h 20 min, so long-day varieties won’t bulb

Precipitation11.2 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: Tohono Chul, AZ (9 mi away); precipitation: Tucson 15.5 Nw, AZ (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

Arizona planting zones →

Questions about 85652

What planting zone is ZIP code 85652?

ZIP code 85652 (Cortaro, 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 Cortaro, AZ?

The median last spring frost (32 °F) near 85652 is February 26; after March 18 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Tohono Chul station.

When is the first frost in Cortaro, AZ?

The median first fall frost near 85652 is December 4, giving a median frost-free growing season of 279 days.

When should I plant tomatoes in 85652?

Start tomato seeds indoors around Jan 1 – Jan 15 and set transplants outside around Mar 5 – Mar 19, one to three weeks after the median last frost.

How much rain and snow does 85652 get?

About 11.2 inches of precipitation a year (NOAA 1991–2020 normals, Tucson 15.5 Nw station).

How hot do summers get in Cortaro, AZ?

The average high peaks at 102 °F in June, with about 159 days a year at 90 °F or more.

What kind of soil does 85652 have?

The USDA soil survey maps Anthony at the center of ZIP 85652: gravelly sandy loam, well drained, pH about 7.9 (alkaline).

Did spring come early in Cortaro, AZ in 2026?

Spring leaf-out near 85652 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 Cortaro, AZ?

Short-day onions: the longest day near 85652 is 14 h 17 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.

Did the zone for 85652 change?

Yes. The 2012 USDA map put 85652 in zone 9a; the 2023 map puts it in zone 9b. The newer map uses 1991–2020 data and more weather stations.