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

Planting zone for 86504 — Fort Defiance, AZ

ZIP code 86504 (Fort Defiance, Apache County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is May 29 and the first fall frost September 28.

Where ZIP 86504 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.

Zone6b−5 to 0 °F

Coldest night−20.6 to −17.8 °C

Last frostMay 29

First frostSep 28

2012 zone6a

Was 6a 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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Fort Defiance, 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 Fort Defiance, AZ

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 29median — 50% chance of a later frost

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

First fall frostSeptember 28median — 10% chance by Sep 16

Growing season121 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 13 and returns around October 4.

From the NOAA station Window Rock Airport, AZ — 15 miles away, elevation 6,739 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 86504

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 17 – May 1

SpinachSow outdoors · Apr 17 – May 8

Broccoli, cabbageStart indoors · Mar 20 – Apr 3

Broccoli, cabbageTransplant · May 8 – May 22

Onion setsPlant outdoors · May 1 – May 15

PotatoesPlant outdoors · May 8 – May 22

LettuceSow outdoors · May 1 – May 15

Carrots, beetsSow outdoors · May 8 – May 22

TomatoesStart indoors · Apr 3 – Apr 17

TomatoesTransplant · Jun 5 – Jun 19

Peppers, eggplantStart indoors · Mar 20 – Apr 3

Peppers, eggplantTransplant · Jun 12 – Jun 26

BeansSow outdoors · Jun 5 – Jun 19

Sweet cornSow outdoors · Jun 5 – Jun 19

Cucumbers, squashSow outdoors · Jun 5 – Jun 19

Fall lettuce, spinachSow outdoors · Aug 3 – Aug 17

GarlicPlant cloves · Sep 14 – Oct 19

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 29) and first fall frost (Sep 28) 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 86504 came on Mar 19 — 18 days earlier than the 1991–2020 average (Apr 6).

average
Apr 62026
Mar 19

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 6b in Arizona

441 plants native to the lower 48 states, recorded in Arizona, and rated by the USDA to survive −5 °F or colder — the bottom of zone 6b. 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 Fort Defiance, AZ.

Soil in Fort Defiance, AZ

The soil mapped at the center of ZIP 86504 is Arabrab — very fine sandy loam, well drained.

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

pH7.6slightly alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1%low — add compost

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Arabrab-Parkelei family complex, dry, 3 to 12 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 86504; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Fort Defiance, AZ

Summer high88 °Faverage high, July

Winter low14 °Faverage low, January

Hot days24days a year at 90 °F or more

Freezing nights196nights a year at 32 °F or less

Growing degree days2,321base 50 °F — the season’s usable heat

Longest day14 h 36 mindaylight on June 21

Shortest day9 h 43 mindaylight on December 21

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

Precipitation11.3 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: Window Rock Airport, AZ (15 mi away); precipitation: Window Rock Airport, AZ (15 mi away). 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.

873286b

Navajo, NM · 13 mi

865156b

Window Rock, AZ · 14 mi

865116a

Saint Michaels, AZ · 15 mi

873206b

Mexican Springs, NM · 15 mi

Arizona planting zones →

Questions about 86504

What planting zone is ZIP code 86504?

ZIP code 86504 (Fort Defiance, AZ) is in USDA hardiness zone 6b on the 2023 map: the coldest night of an average winter reaches −5 to 0 °F (−20.6 to −17.8 °C).

When is the last frost in Fort Defiance, AZ?

The median last spring frost (32 °F) near 86504 is May 29; after June 10 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Window Rock Airport station.

When is the first frost in Fort Defiance, AZ?

The median first fall frost near 86504 is September 28, giving a median frost-free growing season of 121 days.

When should I plant tomatoes in 86504?

Start tomato seeds indoors around Apr 3 – Apr 17 and set transplants outside around Jun 5 – Jun 19, one to three weeks after the median last frost.

How much rain and snow does 86504 get?

About 11.3 inches of precipitation a year (NOAA 1991–2020 normals, Window Rock Airport station).

How hot do summers get in Fort Defiance, AZ?

The average high peaks at 88 °F in July, with about 24 days a year at 90 °F or more.

What kind of soil does 86504 have?

The USDA soil survey maps Arabrab at the center of ZIP 86504: very fine sandy loam, well drained, pH about 7.6 (slightly alkaline).

Did spring come early in Fort Defiance, AZ in 2026?

Spring leaf-out near 86504 came on Mar 19 in 2026, 18 days earlier than the 1991–2020 average (Apr 6), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Fort Defiance, AZ?

Intermediate onions: the longest day near 86504 is 14 h 36 min, so day-neutral types bulb best; long-day varieties may not bulb fully.

Did the zone for 86504 change?

Yes. The 2012 USDA map put 86504 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.