Propagation
Surface sow fresh seeds in boxes, using a sandy-peat media that is lime free and cover the seeds lightly with sphagnum or sand. Keep moist and pot up as soon as large enough to handle.

Semi hardwood tip cuttings that are taken from early to late summer from 25 mm (1 in) to 200 mm (7¾ in) long. All but the top leaves should be removed and they can be reduced by half to improve aeration and reduce evapotranspiration. 

Prepare the base of the cutting by removing a slither of bark up to 25 mm long then dip the end in to hormone rooting powder that contains indolebutyric acid. 

Place the cuttings in a well-drained media and maintain a temperature of 21° C (70° F) and apply water misting on a regular basis. Take care not to over water as this will promote fungal attack. Cuttings should root up within 6-weeks or may take up to 12 months for some species.  

Botanic information
Leaf: The dark green leaves are oblong elliptical to oblong ovate up to 17 mm (⅝ in) wide with a cuneate base and an obtuse apex that maybe mucronate. The pale underside is densely covered in red-brown scales and the petiole is 9 mm (⅜ in) long

Flower: The broad-funnelform flowers have a greenish or reddish calyx with oblong lobes and the corolla is deep blue-purple or pink with a pubescent throat that contains 10-statements. There are 6-10 flowers arranged in an umbel (truss) on a pedestal that is 10 mm to 20 mm (¾ in) long and appear from mid to late spring.

Fruit: The ovoid capsule is densely scally and is accompanied by the persistent calyx. The small seeds are viable of the plant may be reproduced vegetatively.

Culture
Rhododendrons grow best in a sandy loam that is tending acidic and is well drained with a mixture of leaf mould and peat that is kept moist, and friable. 

They do not thrive in clay or limestone based soils with a high pH and is very sensitive to salinity. These shrubs require protection from strong winds due to the shallow root system and dislike hot afternoon sun, preferring a semi-shaded position.  

As they are shallow rooted they are easily transplanted with a good ball of soil kept around the roots. When replanting apply a thick layer of mulch which will retain the soil moisture, improve soil aeration and decrease the penetration of frosts in cold areas. 

When planting from a container you may make vertical slits down the root ball with a sharp knife to ensure contact with the new soil and the hole once planted it should not be allowed to dry out. 

The large leaf forms tolerate a shaded position, under deciduous trees or on the southern side of buildings and the smaller azaleas can tolerate a sunny position, but all forms require adequate light for flowering.  Normally little pruning is required, but rhododendrons will tolerate cutting back if they become leggy or to rejuvenate.