If you have a heavy clay soil, plant your rhododendron in a mound of improved soil as described below. If growing rhododendrons in containers, use an ericaceous compost . Rhododendrons are acid loving plants. Moisture is required for proper rhododendron care. Scientifically speaking, all azaleas are of the genus Rhododendron. Plant the rhododendron bush so that its crown is at the same level as in the pot. Choose a half-barrel for the tallest or those with wide root systems; consider a 10- or 15-gallon container for others. With their shallow roots, rhododendrons can grow well in pots. As such they perform best when the soil is acidic (with a pH between 4.5 and 6.0). Proper soil conditions are very important. Rhododendrons don't like having wet feet; in fact, soggy, waterlogged ground is the most common cause of failure. Place the plant in a tub or bucket for a brief soaking, until air bubbles disappear. The root ball should be soaked prior to planting. Is it a Rhododendron or an Azalea? Select dwarf varieties of rhododendrons when planting in containers. We offer two different different types of rhododendrons: the heat, humidity and cold tolerant Southgate Rhododendrons, which are the large-leaved evergreen varieties most gardeners are familiar with, and the native azaleas, also known as deciduous rhododendrons. Generally large-leaf rhododendrons are less tolerant of sun and wind than small-leaf rhododendrons or evergreen and deciduous azaleas. (See Soil Conditions for more information.) Look at hybrid varieties such as the pink flowering yaks (R. yakushimanum) that bears pink and white flowers, or the Rhododendron lutescens for light-yellow blooms and new leaves that start off red.