Rhododendron maximum (Great Laurel, Rosebay Rhododenron)


Michael's Opinion

Unique evergreen plant with large strap-like leaves, beautiful clusters of late blooming flowers.

Botanical Information

FamilyEricaceae
GenusRhododendron
Speciesmaximum
CategoryWoody
TypeShrub (evergreen)
References"Rhododendron Maximum Fact Sheet". Virginia Tech, 2012. Web. 02 Mar. 2013.
OriginNorth America, from Nova Scotia south to northern Alabama.
Pronunciation

Details

USDA Hardiness Zone3 - 7
USDA Hardiness Ref.
Canadian Hardiness Zone1a - 7a
Canada Hardiness Ref.
RHS Hardiness ZoneH7 - H5
RHS Hardiness Ref.
Temperature (°C)(-37) - (-12)
Temperature (°F)(-35) - 10
Height4-10 m
Spread5-8 m
GrowthSlow
Flowering PeriodJune, July

Description and Growing Information

General DescriptionA later blooming species with a large open and loose form. Long strap-like, medium green leaves are whorled around the stem and give rise to large clusters of inflorescences.
ShapeUpright, multi-stemmed, evergreen shrub, open and loose, broadly spreading, and often forming thickets.
LandscapeA nice focal point in a shade garden, use as a screen or the margins of a wood.
PropagationSemi-ripe cuttings in late summer, 10 cm in length, insert into a propagator with bottom heat. Seeds should be surface sown on fine peat moss as soon as they are ripe and planted in the spring, germinate between temperatures of 13-16°C.
CultivationThrives in part to full shade in acidic, moist well-drained soils.
PestsCrown rot, dieback, aphids, powdery mildew, and leaf scorch.
HabitatForests in cool, damp bog-like conditions.
Bark/Stem DescriptionBark is brown with shallow furrows between elongated scales.
Flower/Leaf Bud DescriptionLarge ovoid flower buds are 1.2 cm pubescent a yellowish-lime green in colour and emerge into a white inflorescence.
Leaf DescriptionR. maximum has large, 10-20 cm long by 4-6 cm wide, dark to medium green leaves, light green to bronze underneath. Leaves are alternately whorled around the stem. The leaf blade is lanceolate to elliptical with entire margins, and a prominent central vein.
Flower DescriptionMonoecious; up to 25 inflorescences are borne in large clusters, each inflorescence measures 2.5-5 cm across and is held up by four leaf-like bracts, five white concave petals are dotted in an olive colour.
Fruit DescriptionCinnamon brown, dehiscent, elongated pods are 1.3 cm in length and split along five lines to reveal tiny seeds inside.
Texture DescriptionLeaf texture is likened to a leather strap.

Photographs