Royal Oak, Michigan, sits in USDA hardiness zone 6b — a band that supports both cool-season staples and warm-season crops chosen to fit the local frost window.
Crops well matched to these conditions include cabbage, hazelnut, lavender, and collard greens — though what thrives on any one site still turns on its specific soil, sun, and drainage.
Even in Royal Oak, no two yards are alike.
A low spot, a south-facing slope, or a stand of trees moves the frost date and sun across a single Royal Oak lot. Enter your address and we'll score 1,086 plants against your land's actual soil, sun, and frost.
We read public map data around Royal Oak — soil, climate, flood, and parcel records. How we handle your address.
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Royal Oak — the short answer
Royal Oak, Michigan: USDA zone 6b, about 216 days between hard freezes, across 8K acres of city.
- USDA zone
- 6b
- USDA PHZM 2023
- Last hard freeze (28°F)
- Apr 7
- NOAA 1991–2020 Climate Normals, 28°F — this town
- First hard freeze (28°F)
- Nov 9
- NOAA 1991–2020 Climate Normals, 28°F — this town
- Days between freezes
- ~216
- NOAA 1991–2020 Climate Normals, 28°F — this town
- City area
- 8K acres
- US Census TIGER/Line 2025
Every figure names the dataset it came from. Hard-freeze dates are this town’s own 28°F normals: light frosts run a few weeks past them, and tender transplants usually wait 2–3 weeks after the last hard freeze.
Hardiness Zone Range
Zone 6b is Royal Oak's average, not your lot's — a low corner or a tree line moves it. Against Royal Oak's 216-day season, see what your own ground reads.
Soil varies lot by lot — soil types explained.
What this means for growing in Royal Oak
Each reading below is measured for Royal Oak itself — here is what it means for a garden here, and the move an experienced grower makes about it.
Season length
MeasuredRoyal Oak runs about 216 days between hard freezes — a long growing season.
There is slack for succession plantings and slow-finishing crops: many vegetables can be sown twice, and the heat-lovers have time to ripen fully.
Plan a second sowing of quick crops after the first comes out, and use the fall window most gardeners let sit idle.
NOAA 1991–2020 Climate Normals
Winter hardiness
MeasuredRoyal Oak sits in USDA hardiness zone 6b.
The zone sets which perennials, shrubs, and fruit trees live through an average winter here — a plant rated for a colder zone is a safe bet, one rated warmer needs winter protection or gets treated as an annual.
Match perennials and fruit to the zone before you buy, so nothing you plant is a gamble against the cold.
USDA PHZM 2023
The kind of country Royal Oak is in
Royal Oak sits in the Huron/Erie Lake Plains — EPA Level III, inside the wider Eastern Temperate Forests. That is read at Royal Oak's own centroid, and it is not what its county reads: Oakland County is mostly Southern Michigan/Northern Indiana Drift Plains. The wider page above you is answering a different question about different ground.
What Grows in Royal Oak
Every plant below cleared Royal Oak's own zone 6b and its 216-day season. Each card opens that plant's Michigan profile. How we score.
Is it too late to plant in Royal Oak?
For most of the year, no — what changes is which crops still fit the days remaining. Cool-season crops can go in from around Mar 10; tender transplants wait until two to three weeks after the last 28°F hard freeze, which lands near Apr 7 (NOAA 1991–2020 climate normals); and from midsummer, planting counts back from the first fall freeze around Nov 9 — long-season crops need about 90 days of runway, quick greens only 30. With a season this long, “too late” mostly means “switch crops” — second sowings and a full fall garden are the norm, with garlic closing the year.
Documented around Royal Oak
Spotted lanternfly documented 10 miles from Royal Oak, first recorded 2022. What to watch for.
What's on the federal record near Royal Oak
Closest first, within ~10 miles of Royal Oak. Listing isn't leaking, and distance isn't exposure.
- Amoco Oil Station #6294Underground Storage Tanks · 1300 ft
- Royal Oak FuelUnderground Storage Tanks · 1500 ft
- K-351 (Citgo)Underground Storage Tanks · 1700 ft
- We've Got Gas LLCUnderground Storage Tanks · 1900 ft
- AMERICAN HOUSEBrownfields · 1900 ft
- AQUA CLEAR LABS LLCBrownfields · 2100 ft
- Alpha Auto IncUnderground Storage Tanks · 2200 ft
- NEW MAGIC CLEANERS INCBrownfields · 2600 ft
- ST JOSEPH MERCY OAKLAND A MEMBER OF TRINITY HEALTHBrownfields · 0.6 mi
- BEAUMONT HEALTH-BERKLEY PTBrownfields · 0.6 mi
- ASSOCIATES IN MEDICINEBrownfields · 0.6 mi
- RED RUN GOLF CLUB - RESTAURANTBrownfields · 0.6 mi
6 more sites are on the record inside the same radius. See them on the map
Measured from Royal Oak's center, not your beds. Run your own address for what's upwind of you specifically.
Environmental Intelligence
The counts behind that headline — every source type on the record near Royal Oak.
Total Sites
5,627
within ~10 miles of Royal Oak
Risk Level
Elevated
Highest-severity
72 Superfund sites (none NPL-listed)
Sources Checked
within ~10 miles of Royal Oak
Severity Distribution
within ~10 miles of Royal Oak
Highest-Severity Sites
A note from Gnorman
What an experienced grower watches for around here
In and around Royal Oak, two things run higher than the national average within ~10 miles of Royal Oak — Brownfields (2,828 sites) and Superfund (72 sites). Knowing it is half the work — and it's nothing a thoughtful grower can't plan for.
Brownfields: Brownfield sites are former commercial or industrial properties where legacy soil contamination (heavy metals, PAHs, petroleum compounds) may persist.
Superfund: Superfund sites represent the most severe contamination in the federal system.
Check EPA brownfield remediation status — many sites have completed cleanup with institutional controls.
Commission professional soil testing before any food production (test for heavy metals, VOCs, and SVOCs).
Check your specific parcel in Royal Oak
Get exact proximity distances to contamination sources for your specific parcel — plus soil, sun, drainage, and 1,086 plant recommendations.
25+ data sources read at your address, not the Royal Oak average
Your land is one point inside Royal Oak
Everything above resolves to Royal Oak as a whole — one PHZM band and one 28°F frost record, read across 8K acres. Your parcel is one point inside that footprint. Slope, tree cover, a low spot that pools cold air, and what is in the soil are all resolved at the address, and none of them are visible at city scale. That is the honest boundary of this page, and the reason the next step is a reading of your own ground rather than a better local average.
Your Lot vs the Royal Oak Average
Royal Oak Average
- ●USDA Zones 6b, averaged across Royal Oak
- ●One soil character for all of Royal Oak
- ●Frost dates read at Royal Oak's scale: Apr 7 to Nov 9
YOUR Parcel
- ✓Your exact zone, not Royal Oak's 6b
- ✓Your SSURGO soil type & pH
- ✓Your sun exposure, cast in 3D
See MY Growing Report
Read your specific parcel in Royal Oak
Pull a site-specific report for your exact address in Royal Oak, Michigan — soil, sun, drainage, frost risk, and scored plant recommendations.
Three things about your lot that Royal Oak averages can't show:
We read public map data around Royal Oak — soil, climate, flood, and parcel records. How we handle your address.
25+ data sources read at your address, not the Royal Oak average
How we know this about Royal Oak
The datasets: hardiness from the USDA ARS Plant Hardiness Zone Map 2023, read at this city’s own centroid; hard-freeze dates from NOAA 1991–2020 28°F normals at Royal Oak’s own record; boundaries and acreage from US Census TIGER/Line 2025; the contamination records from the federal sources named in their beats above. Soil is not read at city grain anywhere on this page — there is no city-resolution survey in our data, which is why you will find no soil grid here rather than a statewide one wearing a local label. The resolution ledger below names every figure this page inherited.
Common questions about Royal Oak
When does frost risk typically end in Royal Oak?
The last hard freeze (28°F) in Royal Oak typically lands around Apr 7, per NOAA 1991–2020 climate normals — earlier than the light-frost dates most charts quote. That marks the hard freeze, not the last light frost — lighter frosts keep biting past it, which is why tender transplants here wait until about Apr 28.
When is the first frost in Royal Oak?
The first hard freeze (28°F) in Royal Oak typically arrives around Nov 9, per NOAA 1991–2020 climate normals — the point tender summer crops finish. Lighter frosts run ahead of it, near Oct 26, so the watching starts about Oct 10 — about 216 days after the spring freeze cleared.
How long is the growing season in Royal Oak?
Measured between 28°F hard freezes, Royal Oak sees about 216 frost-free days — roughly Apr 7 through Nov 9, per NOAA 1991–2020 climate normals. Tender crops work a shorter one: nearer Apr 28 to Oct 26, about 181 days.
Is the soil safe to grow vegetables in Royal Oak?
The federal record around Royal Oak is a meaningful one — 5,627 documented sites, mostly Brownfields entries (2,828), the nearest Underground Storage Tanks record about 0.2 miles out — so a soil test before new food beds is a sensible precaution here, not a reason to hold back from growing. Remember that proximity to a documented site is information, not a diagnosis of any one yard; the contamination map shows exactly what sits where.
How do I protect my plants from frost in Royal Oak?
From about Oct 10 the job here turns from planting to protecting — the last start even a 30-day crop can finish. As the season closes around the first 28°F hard freeze near Nov 9 (NOAA 1991–2020 climate normals), three moves buy time: row cover or an old sheet over tender plants on still, clear nights; water the soil the afternoon before a freeze, so it holds warmth overnight; and harvest tomatoes, peppers and basil before Nov 9. Hardy greens and roots shrug off light frost and sweeten after it — leave them in.
Everything above is measured at Royal Oak's scale — its 6b band and its 216-day season. Your yard writes its own version of Royal Oak's numbers: we read soil, sun, drainage and frost at your exact address. Try it for 14 days — no card required.
What this page reads at Royal Oak’s own scale
7 of the readings below were taken at Royal Oak's own scale — its own ~216-day season between 28°F freezes, the 7,547 acres it covers and 5,627 documented sites around it; 4 are borrowed from a wider read, named and linked below.
Measured here
- Royal Oak's own USDA hardiness band, zones 6bUSDA PHZM 2023
- Royal Oak's own 28°F hard-freeze dates, about Apr 7 and Nov 9 and the ~216-day span between themNOAA 1991–2020 Climate Normals
- 5,627 documented contamination sites on the federal record near Royal Oak, the closest Underground Storage Tanks record about 0.2 miles out from the town centreFederal environmental registers
- Royal Oak's boundary and the 7,547 acres inside itUS Census TIGER/Line 2025
- Which of 1,086 plants clear zones 6b and a ~216-day seasonGrowable Ground crop-matching engine
- Royal Oak sits in the Huron/Erie Lake Plains — not the ecoregion its county mostly readsUS EPA Level III Ecoregions
- A documented spotted-lanternfly record within reach of Royal Oaklydemapr (De Bona & Helmus), 10 km survey lattice
Inherited from a wider read
- Soil character — no town-scale survey exists, so Royal Oak's 7,547 acres read through its county's SSURGO summaryfrom Oakland County
- Growing-degree days and winter chill — measured county-wide only, so the county page carries themfrom Oakland County
- The growing challenges every Michigan grower plans around — written at state scale, so they stay on the state guidefrom Michigan
- Butterfly and beetle records, and the farmland pesticide estimate — all published county-widefrom Oakland County
What this page can’t tell you
- The soil pH, drainage, sun hours, and frost pockets on any one lot among Royal Oak's 7,547 acreswhy one lot differs from the next →
- Which side of Royal Oak you're on — a low spot frosts first and a south wall warms early, and one normal is being asked to speak for all 7,547 acresreading your own microclimate →
- How close that record sits to YOUR lot — the closest Underground Storage Tanks record about 0.2 miles out, measured from the town centrehow we read the record →
- Where cold air settles, which slopes face the sun, and which way the wind runs on your own ground — measured at your address, and averaged away by any Royal Oak-wide figureread your own land →