Rhododendron is a large genus with over 1,000 species of evergreen, semi-evergreen or deciduous shrubs ranging greatly in size and stature. This genus from the Ericaceae family is widely grown for its attractive, sometimes scented, generally 5-lobed flowers. Many hybrids and cultivars have been bred and are commercially available for garden planting. These are used extensively as ornamental landscaping plants and are well adapted to temperate and subtemperate climates. In horticulture, there are four groups: evergreen rhododendrons (includes hardy hybrids), Vireya rhododendrons (frost-tender Malesian shrubs), azaleas (belonging to the botanical section Azalea within the genus Rhododendron), and Azaleodendrons (hybrids between deciduous azaleas and evergreen hybrid rhododendrons). These plants prefer a soil pH of between 4.5 and 5.5 and a high organic matter content. When planting new plants, mix plenty of acidic organic matter such as leaf mould, decomposing pine needles, or composted tree bark into the soil.