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

Planting zone for 86001 — Flagstaff, AZ

ZIP code 86001 (Flagstaff, Coconino County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is June 11 and the first fall frost September 25.

Where ZIP 86001 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.

Zone6a−10 to −5 °F

Coldest night−23.3 to −20.6 °C

Last frostJun 11

First frostSep 25

2012 zone6a

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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Flagstaff, 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 Flagstaff, AZ

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostJune 11median — 50% chance of a later frost

Safe for tender plantsJune 30only 10% chance of frost after

First fall frostSeptember 25median — 10% chance by Sep 8

Growing season99 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 27 and returns around October 4.

From the NOAA station Ft Valley, AZ — 6 miles away, elevation 7,346 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 86001

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 30 – May 14

SpinachSow outdoors · Apr 30 – May 21

Broccoli, cabbageStart indoors · Apr 2 – Apr 16

Broccoli, cabbageTransplant · May 21 – Jun 4

Onion setsPlant outdoors · May 14 – May 28

PotatoesPlant outdoors · May 21 – Jun 4

LettuceSow outdoors · May 14 – May 28

Carrots, beetsSow outdoors · May 21 – Jun 4

TomatoesStart indoors · Apr 16 – Apr 30

TomatoesTransplant · Jun 18 – Jul 2

Peppers, eggplantStart indoors · Apr 2 – Apr 16

Peppers, eggplantTransplant · Jun 25 – Jul 9

BeansSow outdoors · Jun 18 – Jul 2

Sweet cornSow outdoors · Jun 18 – Jul 2

Cucumbers, squashSow outdoors · Jun 18 – Jul 2

Fall lettuce, spinachSow outdoors · Jul 31 – Aug 14

GarlicPlant cloves · Sep 11 – Oct 16

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 11) and first fall frost (Sep 25) 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 86001 came on Mar 20 — 25 days earlier than the 1991–2020 average (Apr 14).

average
Apr 142026
Mar 20

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 6a in Arizona

436 plants native to the lower 48 states, recorded in Arizona, and rated by the USDA to survive −10 °F or colder — the bottom of zone 6a. 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 Flagstaff, AZ.

Soil in Flagstaff, AZ

The soil mapped at the center of ZIP 86001 is Pachic Argiustolls — cobbly silt loam, well drained.

TextureCobbly silt loama good balance for most vegetables

pH5.8moderately acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2%moderate

Hydrologic groupCwater soaks in slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Pachic Argiustolls, Typic Haplustalfs, and Lithic Haplustepts; cool mesic ustic mountains.

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 86001; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Flagstaff, AZ

Summer high84 °Faverage high, July

Winter low16 °Faverage low, December

Hot days6days a year at 90 °F or more

Freezing nights244nights a year at 32 °F or less

Growing degree days1,730base 50 °F — the season’s usable heat

Longest day14 h 33 mindaylight on June 21

Shortest day9 h 46 mindaylight on December 21

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

Precipitation19.1 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: Ft Valley, AZ (6 mi away); precipitation: Fort Valley, AZ (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

860155b

Bellemont, AZ · 10 mi

860026a

Flagstaff, AZ · 13 mi

860186b

Parks, AZ · 14 mi

860056a

Flagstaff, AZ · 21 mi

860046b

Flagstaff, AZ · 22 mi

860467a

Williams, AZ · 23 mi

860166b

Gray Mountain, AZ · 28 mi

860177a

Munds Park, AZ · 29 mi

All 5 ZIP codes in Flagstaff → · Arizona planting zones →

Questions about 86001

What planting zone is ZIP code 86001?

ZIP code 86001 (Flagstaff, AZ) is in USDA hardiness zone 6a on the 2023 map: the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C).

When is the last frost in Flagstaff, AZ?

The median last spring frost (32 °F) near 86001 is June 11; after June 30 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Ft Valley station.

When is the first frost in Flagstaff, AZ?

The median first fall frost near 86001 is September 25, giving a median frost-free growing season of 99 days.

When should I plant tomatoes in 86001?

Start tomato seeds indoors around Apr 16 – Apr 30 and set transplants outside around Jun 18 – Jul 2, one to three weeks after the median last frost.

How much rain and snow does 86001 get?

About 19.1 inches of precipitation a year (NOAA 1991–2020 normals, Fort Valley station).

How hot do summers get in Flagstaff, AZ?

The average high peaks at 84 °F in July, with about 6 days a year at 90 °F or more.

What kind of soil does 86001 have?

The USDA soil survey maps Pachic Argiustolls at the center of ZIP 86001: cobbly silt loam, well drained, pH about 5.8 (moderately acidic).

Did spring come early in Flagstaff, AZ in 2026?

Spring leaf-out near 86001 came on Mar 20 in 2026, 25 days earlier than the 1991–2020 average (Apr 14), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Flagstaff, AZ?

Intermediate onions: the longest day near 86001 is 14 h 33 min, so day-neutral types bulb best; long-day varieties may not bulb fully.