Illustration
Rosebay Rhododendron
Rhododendron maximum
Also called great laurel, great rhododendron, white laurel and american rosebay
Also comes in pink and purple.
Rosebay Rhododendron blooms from June through August.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Rosebay Rhododendron
Plant it in part shade. It prefers moderate water. It is hardy in USDA zones 3–7. Expect it to reach about 11 ft tall and 9.5 ft wide at maturity, in roughly 4 years (a house reading).
Is Rosebay Rhododendron toxic to dogs or cats?
- Listed as toxic to dogs and cats by NC State Extension, Pet Poison Helpline and Royal Horticultural Society.
- Listed as poisonous to people by NC State Extension and Royal Horticultural Society.
Lists differ and none is complete. If a pet eats a plant and seems unwell, call a veterinarian or a pet poison helpline.
What was checked
Nine facts were checked against named botanical sources, each recorded beside the sources that carried it: mature height and spread, hardiness zones, sun, water, bloom months and color, the trait tags, and years to mature size, which rests on a recorded house rule where no publisher states one and is marked so. Soil, diseases, pests, toxicity and the plant's own names have not yet been read for this plant, and its trait tags are the ones a feature uses rather than every word a page prints. Each fact above carries its own mark. The planting, spacing and size sections are derived from these checked facts by a fixed rule, not checked separately, and the plant type is the library's own classification.
When to plant Rosebay Rhododendron
Plant Rosebay Rhododendron in early spring as soon as the soil is workable, or in early fall at least six weeks before your first frost, so roots establish in cool weather. In zone 5, the middle of its hardy zones 3 to 7, spring means April to June and fall means August or September. Once settled, it blooms from June to August.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 5, the middle of this plant's hardy range, start with zone 5 in April. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does Rosebay Rhododendron get?
11 fttall5 ft 7 inan adult9.5 ftwideSee Rosebay Rhododendron in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.
How far apart to plant Rosebay Rhododendron
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Give Rosebay Rhododendron about 9.5 ft of clear ground in every direction, measured from its center. It is one plant with room around it, not a row, and a raised bed is too small for it.
Add Rosebay Rhododendron to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.
Where these facts come from
Rosebay Rhododendron's height, spread, hardiness zones, sun, water, bloom months and color and trait tags were checked against 8 published sources on October 24, 2026. Each one is linked below with every fact it carried, which can include a fact this page still marks as not yet checked, because a source carrying a value is not the same as the value being held to the standard. Facts not in that list, and the planting, spacing and size sections, are not covered by these sources.
- Missouri Botanical GardenPlant Finderheight, spread, hardiness zones, sun, water, bloom months and color and trait tags
- Mt. Cuba Centerheight, spread, hardiness zones, sun, water, bloom months and color and trait tags
- NC State ExtensionPlant Toolboxheight, spread, hardiness zones, sun, water, bloom months and color and trait tags
- plantfinder.nativeplanttrust.orgNative Plant Trustheight, spread, hardiness zones, water, bloom months and color and trait tags
- woodyplants.cals.cornell.eduCornell University Woody Plants Databaseheight, spread, hardiness zones, water, bloom months and color and trait tags
- plantdatabase.uconn.eduUniversity of Connecticut Plant Databaseheight, hardiness zones, sun, bloom months and color and trait tags
- tlcwholesalenursery.comTLC Wholesale Nurseryheight, spread, hardiness zones, water and bloom months and color
- RHSRoyal Horticultural Societyheight, sun and bloom months and color
How the checking works, and what each standard covers, is on the verified plants page.
Where it grows wild
Native to 20 states
United States: Alabama, Connecticut, Delaware, Georgia, Kentucky, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Vermont, Virginia, West Virginia and 8 more
Recorded growing wild in 314 counties.
Range data from the World Checklist of Vascular Plants, Royal Botanic Gardens, Kew (CC BY 4.0, adapted) and USDA PLANTS. How the native range is credited.
Featured in these guides
Explore similar plants
You might also like
Design a garden with this
Drop this plant onto a 3D plan, see how it fills in, and watch your whole garden bloom across the year.