Variation
Rhododendron x mucronatum var ripense
This semi evergreen shrub grows to 1 m (3 ft) tall and wide with mid-green lanceolate or oblanceolate leaves to 50 mm (2 in) long and produces rose-purple funnel-shaped flowers in a terminal umbel during mid-spring.

Cultivars
There are many cultivars and it is advised to contact your local nursery for available varieties.

'Delaware Valley White'
This semi evergreen shrub grows to 3 m (10 ft) tall by 2 m (6 ft) wide with small elliptical leaves and forms a compact bushy habit. It produces clusters of large funnelform white, single flowers during mid-spring and is very showy. It prefers a semi-shaded to full sun wind protected position and grows in organic rich well-drained sandy to clay loam soils that are tending acidic with a pH 4.5-6. It grows in USDA zones 7-9.

'Fujimanyo'
This semi evergreen shrub grows to 2 m (6 ft) tall by 1.5 m (5 ft) wide with narrow lanceolate mid-green leaves and forms a compact bushy habit. During mid-spring it produces double pale pink flowers in a small terminal trusses. 

It prefers a semi-shaded wind protected position and grows in most well-drained fertile moist sandy to like clay soils that are tending acidic. It may be difficult to obtain outside its native region requiring a specialist nursery.

'Kyokanoko'
This evergreen shrub grows to 2 m (6 ft) tall and wide with mid-green elliptical leaves forming a bushy habit. It produces large trusses of single white funnelform flowers that are flushed pink or have a pink marketing towards the centre and appears during mid-spring. 

It prefers a semi-shaded to sunny position and grows in most well-drained fertile moist sandy to clay soils that are tending acidic, with a pH 4.5-6. It grows in USDA zones 7-9.

'Nankinmurasaki'
This semi evergreen shrub grows to 2 m (6 ft) tall and wide with elliptical mid-green leaves and forms a compact bushy habit. During mid-spring it produces single purplish pink flowers with reddish markings towards the upper centre and appears in small terminal trusses. 

It prefers a semi-shaded wind protected position and grows in most well-drained fertile moist sandy to like clay soils that are tending acidic. It may be difficult to obtain outside its native region requiring a specialist nursery.

'Shirayuki'
This semi evergreen shrub grows to 2 m (6 ft) tall by 1.5 m (5 ft) wide with elliptical mid-green leaves and forms a compact bushy habit. During mid-spring it produces single white flowers in a small terminal trusses.  

It prefers a semi-shaded wind protected position and grows in most well-drained fertile moist sandy to like clay soils that are tending acidic. It may be difficult to obtain outside its native region requiring a specialist nursery.

'Usuyo'
This semi evergreen spreading shrub grows to 2 m (6 ft) tall and wide with a narrow elliptical mid-green leaves and forms a compact bushy habit. During mid-spring it produces single bright pink flowers with exserted stamens and is arranged in a small terminal truss.  

It prefers a semi-shaded wind protected position and grows in most well-drained fertile moist sandy to like clay soils that are tending acidic.  It may be difficult to obtain outside its native region requiring a specialist nursery.