Rhododendrons are known for their glossy, green leaves and large flowers. Different types bloom in different colors, including white, purple, pink, red, orange and yellow. Rhododendrons range in size from dwarf shrubs to medium-sized trees. Most rhododendrons thrive in humid climates with mild winters, although there are hardy varieties that survive colder temperatures. The American Rhododendron Society identifies fast growing rhododendrons that reach a height of 7 feet after 10 years. These types include Brittenhill Bugle, Mount Everest and Rhododendron watsonii.
The Brittenhill Bugle rhododendron is a hybrid of the Karkov and Red Loderi rhododendrons. The leaves are green and not as glossy as other rhododendrons, and are tightly packed, according to Greer Gardens. The large, red flowers are bugle shaped and bloom in the early spring. The rhododendron is hardy to zero degrees. Britt Smith, a member of the Hybridizers Study Group, developed this plant.
The Mount Everest is a 1930s-era English hybrid of the campanulatum and griffithianum rhododendrons. The shrub has small, rounded leaves, according to "Rhododendron Hybrids" by Homer E. Salley and Harold E. Greer. The flowers are white, funnel-shaped and slightly fragrant. The plant blooms in the spring and is hardy to -5 degrees. This plant was hybridized at the Slocock nursery in England.
Rhododendron watsonii is a species rhododendron, which means it is a native plant, in this case from China. The watsonii is a winter-flowering rhododendron, according to "Winter-flowering Shrubs" by Michael W. Buffin. The plant blooms in white flowers with pink edges and red blotches in February and March. The watsonii is hardy to 5 degrees. The leaves are spear-shaped and grow to a range of 6 to 9 inches in length. The leaf stems, or petioles, are flattened. Because of its height, it is often classified as a small tree.