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.

Take semi hardwood or tip cuttings from early to late summer and make them 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 (1 in) 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.  

Cultivars may be grafted onto a rootstock and aerial or ground layering is carried out during the growing period.

Botanic information
Leaf: The lanceolate leaves are up to 460 mm (26 in) long and in some cultivars the margins are recurved. They are arranged alternately or whorled and the texture is leathery with scaly or hairy undersides.

Flower: The flowers are funnelform to campanulate, tubulate or urceolate. They are arranged in a cluster with up to 20 blooms appearing at the end of the branches during spring. The colour range includes crimson, cream and orange.

Fruit: Small woody capsule contains numerous seeds. The small seeds are viable but the plant is commonly reproduced vegetatively to maintain true to type.

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.