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

Planting zone for 48073 — Royal Oak, MI

ZIP code 48073 (Royal Oak, Oakland County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is April 26 and the first fall frost October 22.

Where ZIP 48073 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 frostApr 26
First frostOct 22
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 Royal Oak, MI…

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 Royal Oak, MI

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 26median — 50% chance of a later frost
Safe for tender plantsMay 12only 10% chance of frost after
First fall frostOctober 22median — 10% chance by Oct 7
Growing season177 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 16 and returns around November 4.

From the NOAA station Pontiac Wwtp, MI — 9 miles away, elevation 889 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 48073

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 15 – Mar 29
SpinachSow outdoors · Mar 15 – Apr 5
Broccoli, cabbageStart indoors · Feb 15 – Mar 1
Broccoli, cabbageTransplant · Apr 5 – Apr 19
Onion setsPlant outdoors · Mar 29 – Apr 12
PotatoesPlant outdoors · Apr 5 – Apr 19
LettuceSow outdoors · Mar 29 – Apr 12
Carrots, beetsSow outdoors · Apr 5 – Apr 19
TomatoesStart indoors · Mar 1 – Mar 15
TomatoesTransplant · May 3 – May 17
Peppers, eggplantStart indoors · Feb 15 – Mar 1
Peppers, eggplantTransplant · May 10 – May 24
BeansSow outdoors · May 3 – May 17
Sweet cornSow outdoors · May 3 – May 17
Cucumbers, squashSow outdoors · May 3 – May 17
Fall lettuce, spinachSow outdoors · Aug 27 – Sep 10
GarlicPlant cloves · Oct 8 – Nov 12
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 26) and first fall frost (Oct 22) 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 48073 came on Apr 1 — 6 days earlier than the 1991–2020 average (Apr 7).

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 Michigan

582 plants native to the lower 48 states, recorded in Michigan, and rated by the USDA to survive −5 °F or colder — the bottom of zone 6b. Each links to its USDA PLANTS profile.

Trees 58

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican chestnut115 ft · blooms early summer · high shade tolerance · to −33 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Farborvitae50 ft · blooms mid spring · medium shade tolerance · to −33 °F

Shrubs 105

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican hornbeam30 ft · blooms mid spring · low shade tolerance · to −34 °F

Wildflowers & perennials 221

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine bistort1 ft · blooms mid spring · high shade tolerance · to −38 °Falpine sweetvetch2 ft · blooms early summer · high shade tolerance · to −62 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °F

Grasses 175

alpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °FAmerican beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fautumn bluegrass1.5 ft · blooms late spring · medium shade tolerance · to −8 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °Fbeaked sedge4 ft · blooms late spring · low shade tolerance · to −38 °F

Vines 8

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °Ftrumpet creeper2 ft · blooms summer · high shade tolerance · to −13 °F

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 Royal Oak, MI.

Soil in Royal Oak, MI

The soil mapped at the center of ZIP 48073 is Thetford — loamy fine sand, somewhat poorly drained. Much of the area is built over (urban land); this is the natural soil underneath.

TextureLoamy fine sanddrains and warms fast; dries out and needs more feeding
pH6.5neutral; most vegetables like 6.0–7.0
DrainageSomewhat poorly drainedconsider raised beds
Organic matter2.5%moderate
Hydrologic groupA/Ddrains fast once dried out; wet otherwise
Farmland classNot prime farmlandUSDA classification

Map unit: Urban land-Thetford complex, 0 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 48073; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Royal Oak, MI

Summer high82 °Faverage high, July
Winter low17 °Faverage low, January
Hot days10days a year at 90 °F or more
Freezing nights135nights a year at 32 °F or less
Growing degree days2,869base 50 °F — the season’s usable heat
Longest day15 h 18 mindaylight on June 21
Shortest day9 h 03 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation33.9 inper year, rain and melted snow
Snowfall36 inper year; 62 days with snow on the ground

Average high and low, by month

10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 31 °F, low 17 °F 31°17° JanFebruary: average high 34 °F, low 18 °F 34°18° FebMarch: average high 44 °F, low 26 °F 44°26° MarApril: average high 58 °F, low 36 °F 58°36° AprMay: average high 69 °F, low 49 °F 69°49° MayJune: average high 78 °F, low 59 °F 78°59° JunJuly: average high 82 °F, low 63 °F 82°63° JulAugust: average high 81 °F, low 62 °F 81°62° AugSeptember: average high 74 °F, low 54 °F 74°54° SepOctober: average high 61 °F, low 42 °F 61°42° OctNovember: average high 47 °F, low 32 °F 47°32° NovDecember: average high 36 °F, low 24 °F 36°24° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″January: 2.18 in precipitation, 12.1 in snowfall 2.2❄12 JanFebruary: 1.87 in precipitation, 9 in snowfall 1.9❄9 FebMarch: 2.19 in precipitation, 4.1 in snowfall 2.2❄4 MarApril: 2.94 in precipitation, 0.9 in snowfall 2.9❄1 AprMay: 3.81 in precipitation 3.8 MayJune: 3.29 in precipitation 3.3 JunJuly: 3.14 in precipitation 3.1 JulAugust: 3.24 in precipitation 3.2 AugSeptember: 2.92 in precipitation 2.9 SepOctober: 2.90 in precipitation, 0.1 in snowfall 2.9 OctNovember: 3.15 in precipitation, 1.7 in snowfall 3.1❄2 NovDecember: 2.25 in precipitation, 8.1 in snowfall 2.3❄8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Pontiac Wwtp, MI (9 mi away); precipitation: Pontiac Wwtp, MI (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6b.

480176b
Clawson, MI · 1 mi
480726b
Berkley, MI · 2 mi
480686b
Royal Oak, MI · 2 mi
480676b
Royal Oak, MI · 2 mi
480706b
Huntington Woods, MI · 3 mi
480846b
Troy, MI · 3 mi
480126b
Birmingham, MI · 3 mi
480096b
Birmingham, MI · 3 mi

All 3 ZIP codes in Royal Oak → · Michigan planting zones →

Questions about 48073

What planting zone is ZIP code 48073?

ZIP code 48073 (Royal Oak, MI) 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 Royal Oak, MI?

The median last spring frost (32 °F) near 48073 is April 26; after May 12 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Pontiac Wwtp station.

When is the first frost in Royal Oak, MI?

The median first fall frost near 48073 is October 22, giving a median frost-free growing season of 177 days.

When should I plant tomatoes in 48073?

Start tomato seeds indoors around Mar 1 – Mar 15 and set transplants outside around May 3 – May 17, one to three weeks after the median last frost.

How much rain and snow does 48073 get?

About 33.9 inches of precipitation a year and 36 inches of snowfall (NOAA 1991–2020 normals, Pontiac Wwtp station).

How hot do summers get in Royal Oak, MI?

The average high peaks at 82 °F in July, with about 10 days a year at 90 °F or more.

What kind of soil does 48073 have?

The USDA soil survey maps Thetford at the center of ZIP 48073: loamy fine sand, somewhat poorly drained, pH about 6.5 (neutral).

Did spring come early in Royal Oak, MI in 2026?

Spring leaf-out near 48073 came on Apr 1 in 2026, 6 days earlier than the 1991–2020 average (Apr 7), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Royal Oak, MI?

Long-day onions: the longest day near 48073 is 15 h 18 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 48073 change?

Yes. The 2012 USDA map put 48073 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.