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. 

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.
Aerial or ground layering during the growing period.

Botanic information
Leaf: The leathery textured glabrous leaves are oblong-lanceolate to oblanceolate up to 70 mm (2⅔ in) wide with a petiole to 25 mm (1 in) long. The upper surface is dark green and the underside is pale green. The margin is entire and slightly recurved with an abruptly acuminate apex and a cuneate base.

Flower: The flowers have 5-notched expanding white petals that form a broad campanulate corolla with carmine-red markings in the base of the throat. The long pedestal is also carmine-red and up to 12-flowers are arranged in a terminal umbel-like truss that appears in mid spring. 

Fruit: The small woody obliquely ovoid capsule contains numerous tiny 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 are 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.