Rhododendron maximum

Rosebay Rhododendron




  • eastern North America
  • zone 4

Habit and Form

  • multi-stemmed, evergreen, large shrub
  • typically 8' to 15' tall, but can reach to 30' in Appalachian Mountains
  • branching habit is upright and spreading to irregular
  • texture is coarse and it is somewhat loose and open

Summer Foliage

  • leaves are evergreen, broadest above the middle
  • leaves are thick, leathery and dark green
  • 4" to 8" long, somewhat strap-like
  • underside of leaves is either green or a light rusty color
  • upperside is dark green

Autumn Foliage

  • no fall color
  • evergreen


  • blooms later than most large-leaved rhododendrons in late June
  • flowers are rose-pink, pink margined, or nearly white
  • newly emerging shoot sometimes partially obscure the flowers
  • individual flowers are 1.5" across and are borne in crowned clusters of up to 25 flowers
  • flower buds are distictly larger than vegetative buds.
  • flower bud are surrounded at the base with leaf-like bracts


  • dehiscent capsule
  • not ornamentally attractive


  • color is brown, with light ridges and furrows
  • trunks often picturesque in the way they are contorted and twisted


  • partial shade; tolerates relatively dense shade
  • moist, cool, acidic, well-drained, organic soil
  • avoid windswept, exposed or hot locations
  • remove flower clusters following bloom to stimulate new growth and flower bud set
  • transplant from containers or B&B.

Landscape Use

  • shrub border
  • shady locations
  • naturalistic areas
  • edge of woods
  • as a screen


  • lacebug
  • phytophthora root rot
  • winterburn in exposed sites
  • chlorosis on high pH soils
  • leaves roll up in temperatures below 25o F to conserve moisture and unfurl when warm temperatures return
  • flowers partially hidden by new shoots

ID Features

  • long evergreen, strap-like leaves
  • large flower buds surround by leaf-like bracts at the base
  • large size for a rhododendron
  • late blooming rhododendron (late June)


  • by seed
  • by fall or winter stem cuttings


var. album - The flowers of this form are white or nearly so.

var. purpureum - Plants of this type have flowers colored deep pink to purple with green spotting.

var. roseum (also known as 'Roseum') - The emerging buds of this variety appear reddish and open to reveal pink flowers. It is a vigorous grower (to 12' tall) that offers reddish stems and dark green foliage.

'Leachii' (also known as var. leachii) - This form features leaves that are smaller than typical with deeply wavy margins. The plant is more compact than the species with pinkish-white blooms.

'Midsummer' - This cultivar bears pink blooms with a slightly gold throat. The healthy foliage is deep green and the habit is more open than the species.

'Pride's Pink' - A hardy plant with an upright-spreading habit, this cultivar has large pink blooms.

© Copyright Mark H. Brand, 1997-2015.

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Citation and Acknowledgements: University of Connecticut Plant Database, http://hort.uconn.edu/plants, Mark H. Brand, Department of Plant Science and Landscape Architecture, Storrs, CT 06269-4067 USA.