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

Planting zone for 85601 — Arivaca, AZ

ZIP code 85601 (Arivaca, Pima County) is in USDA zone 8b: the coldest winter night averages 15 to 20 °F. The median last spring frost is March 21 and the first fall frost November 20.

Where ZIP 85601 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.

Zone8b15 to 20 °F

Coldest night−9.4 to −6.7 °C

Last frostMar 21

First frostNov 20

2012 zone8b

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 8b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Arivaca, 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 Arivaca, AZ

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMarch 21median — 50% chance of a later frost

Safe for tender plantsApril 14only 10% chance of frost after

First fall frostNovember 20median — 10% chance by Nov 1

Growing season246 daysfrost-free, median

A hard freeze (28 °F) usually ends around February 20 and returns around December 3.

From the NOAA station Sasabe, AZ — 14 miles away, elevation 3,589 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 85601

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Feb 7 – Feb 21

SpinachSow outdoors · Feb 7 – Feb 28

Broccoli, cabbageStart indoors · Jan 10 – Jan 24

Broccoli, cabbageTransplant · Feb 28 – Mar 14

Onion setsPlant outdoors · Feb 21 – Mar 7

PotatoesPlant outdoors · Feb 28 – Mar 14

LettuceSow outdoors · Feb 21 – Mar 7

Carrots, beetsSow outdoors · Feb 28 – Mar 14

TomatoesStart indoors · Jan 24 – Feb 7

TomatoesTransplant · Mar 28 – Apr 11

Peppers, eggplantStart indoors · Jan 10 – Jan 24

Peppers, eggplantTransplant · Apr 4 – Apr 18

BeansSow outdoors · Mar 28 – Apr 11

Sweet cornSow outdoors · Mar 28 – Apr 11

Cucumbers, squashSow outdoors · Mar 28 – Apr 11

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 21) 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 85601 came on Jan 27 — 4 days earlier than the 1991–2020 average (Jan 31).

average
Jan 312026
Jan 27

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 8b in Arizona

482 plants native to the lower 48 states, recorded in Arizona, and rated by the USDA to survive 15 °F or colder — the bottom of zone 8b. 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 Arivaca, AZ.

Soil in Arivaca, AZ

The soil mapped at the center of ZIP 85601 is Deloro — extremely channery loam, well drained.

TextureExtremely channery loama good balance for most vegetables

pH6.7neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2%moderate

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Deloro-Schrap association, 1 to 8 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 85601; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Arivaca, AZ

Summer high97 °Faverage high, June

Winter low35 °Faverage low, January

Hot days118days a year at 90 °F or more

Freezing nights31nights a year at 32 °F or less

Growing degree days5,798base 50 °F — the season’s usable heat

Longest day14 h 13 mindaylight on June 21

Shortest day10 h 05 mindaylight on December 21

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

Precipitation17.9 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: Sasabe, AZ (14 mi away); precipitation: Arivaca, AZ (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

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

Tumacacori, AZ · 17 mi

Green Valley, AZ · 21 mi

856399a

Topawa, AZ · 24 mi

Arizona planting zones →

Questions about 85601

What planting zone is ZIP code 85601?

ZIP code 85601 (Arivaca, AZ) is in USDA hardiness zone 8b on the 2023 map: the coldest night of an average winter reaches 15 to 20 °F (−9.4 to −6.7 °C).

When is the last frost in Arivaca, AZ?

The median last spring frost (32 °F) near 85601 is March 21; after April 14 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Sasabe station.

When is the first frost in Arivaca, AZ?

The median first fall frost near 85601 is November 20, giving a median frost-free growing season of 246 days.

When should I plant tomatoes in 85601?

Start tomato seeds indoors around Jan 24 – Feb 7 and set transplants outside around Mar 28 – Apr 11, one to three weeks after the median last frost.

How much rain and snow does 85601 get?

About 17.9 inches of precipitation a year (NOAA 1991–2020 normals, Arivaca station).

How hot do summers get in Arivaca, AZ?

The average high peaks at 97 °F in June, with about 118 days a year at 90 °F or more.

What kind of soil does 85601 have?

The USDA soil survey maps Deloro at the center of ZIP 85601: extremely channery loam, well drained, pH about 6.7 (neutral).

Did spring come early in Arivaca, AZ in 2026?

Spring leaf-out near 85601 came on Jan 27 in 2026, 4 days earlier than the 1991–2020 average (Jan 31), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Arivaca, AZ?

Short-day onions: the longest day near 85601 is 14 h 13 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.