Rhododendron maximum

RHS Plant Profile
great laurel

Other common names

American rosebay

Shrubs

A large evergreen shrub or small tree, usually up to about 3.5m high in cultivation, though can reach up to 10m in the wild. Leaves are elliptic, up to 20cm long, with fine rust-coloured felting on the undersides when young, and sparse hairs on the leaf stems. Late flowering, producing dense clusters of 14-25 small, bell-shaped flowers, in shades from white to lilac pink and with yellow-green speckles on the upper petals, in summer

Position

Partial shade

Soil Types

Clay, Loam, Sand

Max Height

2.5-4 metres

Max Spread

2.5-4 metres

Size

Time to Maturity
5–10 years
Max Spread
2.5-4 metres
Max Height
2.5-4 metres

Growing Conditions

Clay Loam Sand
Moisture
Moist but well–drained
pH
Acid

Position

Partial shade
Aspect
North–facing or West–facing
Exposure
Sheltered
Hardiness
H7

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Ericaceae
Native to GB/Ireland
No
Foliage
Evergreen
Habit
Columnar upright
Potentially harmful
Harmful if eaten. Wear gloves and other protective equipment when handling. Pets (dogs, cats, rabbits, tortoises) Harmful if eaten - for further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants
Genus
Rhododendron can be evergreen or deciduous shrubs or trees, with simple leaves, sometimes with a dense colourful indumentum of hairs on the lower side, and funnel-shaped, bell-shaped or tubular flowers that may be solitary or in short racemes
Name Status
Correct
Plant Range
Eastern N America

How to Grow

Cultivation

Grow in moist but well-drained, humus rich, acidic soil, in partial or dappled shade. Choose a site away from frost pockets and sheltered from strong winds, and do not allow plants to dry out. Mulch annually, ideally with leaf mould. See rhododendron cultivation for more detailed advice

Propagation

Propagate by semi-ripe cuttings in late summer, by layering in autumn, or by grafting in winter

Suggested planting locations and garden types

  • Cottage and informal garden
  • Flower borders and beds
  • Wall side borders

Pruning

Minimal pruning required, see pruning group 8 (evergreens)

Pests

May be susceptible to vine weevil, rhododendron and azalea whitefly, rhododendron leafhopper, Pieris lacebug, scale insects, caterpillars and aphids

Diseases

May be susceptible to powdery mildews, honey fungus, silver leaf and Phytophthora, as well as more specific Rhododendron diseases