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

Planting zone for 85551 — Solomon, AZ

ZIP code 85551 (Solomon, Graham County) is in USDA zone 8b: the coldest winter night averages 15 to 20 °F. The median last spring frost is March 25 and the first fall frost November 9.

Where ZIP 85551 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 25
First frostNov 9
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 Solomon, 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 Solomon, AZ

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 25median — 50% chance of a later frost
Safe for tender plantsApril 14only 10% chance of frost after
First fall frostNovember 9median — 10% chance by Oct 23
Growing season228 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 3 and returns around November 22.

From the NOAA station Safford Ag Center, AZ — 9 miles away, elevation 2,953 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 85551

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 11 – Feb 25
SpinachSow outdoors · Feb 11 – Mar 4
Broccoli, cabbageStart indoors · Jan 14 – Jan 28
Broccoli, cabbageTransplant · Mar 4 – Mar 18
Onion setsPlant outdoors · Feb 25 – Mar 11
PotatoesPlant outdoors · Mar 4 – Mar 18
LettuceSow outdoors · Feb 25 – Mar 11
Carrots, beetsSow outdoors · Mar 4 – Mar 18
TomatoesStart indoors · Jan 28 – Feb 11
TomatoesTransplant · Apr 1 – Apr 15
Peppers, eggplantStart indoors · Jan 14 – Jan 28
Peppers, eggplantTransplant · Apr 8 – Apr 22
BeansSow outdoors · Apr 1 – Apr 15
Sweet cornSow outdoors · Apr 1 – Apr 15
Cucumbers, squashSow outdoors · Apr 1 – Apr 15
Fall lettuce, spinachSow outdoors · Sep 14 – Sep 28
GarlicPlant cloves · Oct 26 – Nov 30
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 25) and first fall frost (Nov 9) 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 85551 came on Jan 31 — 3 days earlier than the 1991–2020 average (Feb 3).

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).

Soil in Solomon, AZ

The soil mapped at the center of ZIP 85551 is Tres Hermanos — gravelly loam, well drained.

TextureGravelly loama good balance for most vegetables
pH8.2alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter0.75%low — add compost
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Tres Hermanos gravelly loam.

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 85551; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Solomon, AZ

Summer high100 °Faverage high, June
Winter low30 °Faverage low, January
Hot days142days a year at 90 °F or more
Freezing nights70nights a year at 32 °F or less
Growing degree days5,967base 50 °F — the season’s usable heat
Longest day14 h 19 mindaylight on June 21
Shortest day9 h 59 mindaylight on December 21
Onions to growIntermediateday-neutral types bulb best; long-day varieties may not bulb fully
Precipitation8.8 inper year, rain and melted snow

Average high and low, by month

20°30°40°50°60°70°80°90°100°110°32 °FJanuary: average high 62 °F, low 30 °F 62°30° JanFebruary: average high 67 °F, low 34 °F 67°34° FebMarch: average high 74 °F, low 39 °F 74°39° MarApril: average high 83 °F, low 46 °F 83°46° AprMay: average high 91 °F, low 54 °F 91°54° MayJune: average high 100 °F, low 63 °F 100°63° JunJuly: average high 99 °F, low 69 °F 99°69° JulAugust: average high 97 °F, low 68 °F 97°68° AugSeptember: average high 93 °F, low 61 °F 93°61° SepOctober: average high 84 °F, low 48 °F 84°48° OctNovember: average high 72 °F, low 37 °F 72°37° NovDecember: average high 61 °F, low 30 °F 61°30° Dec

Precipitation by month inches

0″1″2″January: 0.71 in precipitation, 0.2 in snowfall 0.7 JanFebruary: 0.66 in precipitation 0.7 FebMarch: 0.45 in precipitation 0.5 MarApril: 0.21 in precipitation 0.2 AprMay: 0.18 in precipitation 0.2 MayJune: 0.27 in precipitation 0.3 JunJuly: 1.35 in precipitation 1.4 JulAugust: 1.84 in precipitation 1.8 AugSeptember: 1.08 in precipitation 1.1 SepOctober: 0.75 in precipitation 0.8 OctNovember: 0.51 in precipitation 0.5 NovDecember: 0.77 in precipitation 0.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Safford Ag Center, AZ (9 mi away); precipitation: Safford Ag Center, AZ (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

855468b
Safford, AZ · 3 mi
855488b
Safford, AZ · 12 mi
855528b
Thatcher, AZ · 14 mi
855318b
Central, AZ · 16 mi
855408b
Morenci, AZ · 21 mi
855348a
Duncan, AZ · 24 mi
855438b
Pima, AZ · 25 mi
855358b
Eden, AZ · 27 mi

Arizona planting zones →

Questions about 85551

What planting zone is ZIP code 85551?

ZIP code 85551 (Solomon, 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 Solomon, AZ?

The median last spring frost (32 °F) near 85551 is March 25; after April 14 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Safford Ag Center station.

When is the first frost in Solomon, AZ?

The median first fall frost near 85551 is November 9, giving a median frost-free growing season of 228 days.

When should I plant tomatoes in 85551?

Start tomato seeds indoors around Jan 28 – Feb 11 and set transplants outside around Apr 1 – Apr 15, one to three weeks after the median last frost.

How much rain and snow does 85551 get?

About 8.8 inches of precipitation a year (NOAA 1991–2020 normals, Safford Ag Center station).

How hot do summers get in Solomon, AZ?

The average high peaks at 100 °F in June, with about 142 days a year at 90 °F or more.

What kind of soil does 85551 have?

The USDA soil survey maps Tres Hermanos at the center of ZIP 85551: gravelly loam, well drained, pH about 8.2 (alkaline).

Did spring come early in Solomon, AZ in 2026?

Spring leaf-out near 85551 came on Jan 31 in 2026, 3 days earlier than the 1991–2020 average (Feb 3), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Solomon, AZ?

Intermediate onions: the longest day near 85551 is 14 h 19 min, so day-neutral types bulb best; long-day varieties may not bulb fully.