This family of plants contains an option for every landscape, from the giant rhododendrons of East Asian mountainsides to the rosebay rhododendrons native to Eastern U.S. woodlands. These often-broadleaf evergreen plants boast large clusters of showy blooms at their growing tips in spring. In areas where dry winters tend to desiccate evergreen types, deciduous varieties of rhododendrons can fill in the gap.
A classic shade garden plant, rhododendrons are prized for their glossy green foliage and showy clusters of blooms. Available in a wide variety of colors, the most common flowers are borne in ranges of purples and pinks as well as white and cream. Many of the deciduous types also boast bright yellow and orange hues that work wonders in brightening up shady corners of the garden.
Rhododendron Care Must-Knows
The rhododendron is a wonderful addition to any shade garden. Deciduous varieties can hold up much better to more sun, as many of the evergreen types can be susceptible to burn in winter where they are exposed. To prevent this, plant evergreen types in sheltered areas, avoiding southern exposures where warm, sunny winter days can be fatal. Keep them sheltered from drying winter winds as well. Evergreen types may begin to curl their leaves during the winter, and this is actually a physiological response to dry winter weather. By curling their leaves, they are protecting themselves from cold temperatures and winds in order to prevent potential winter burn.
Rhododendron plants, similar to many other plants in the Ericaceae family, prefer acidic soils. Ideal soil pH for rhododendron plants is somewhere between 4.5 and 6.0. If you have had problems growing rhododendrons in the past, perform a soil test. You can amend the soils with peat moss, compost, and other soil acidifiers to keep them happy.
Rhododendron also appreciates soil that has lots of organic material. This will keep the shrubs decently moist and prevent them from drying out—dry winters and late falls can be particularly fatal to rhododendrons. On the other end of the spectrum, overly wet soils can also be fatal to rhododendrons. Finding the right balance of moisture in soils can be tricky.
Pruning may be necessary to create a more desirable shape and overall more visually appealing plant. After the plants have bloomed, spent blossoms can be cut back to the new growing tips. After bloom is also the ideal time to do any other pruning. Damaged or diseased growth should always be removed to prevent the spread of disease. You can also do rejuvenation pruning by cutting older plants back more severely to encourage better branching.
Rhododendron or Azalea?
Rhododendrons and azaleas often get confused. A while ago, azaleas were considered a separate genus of plants, but since they have been found very genetically similar to rhododendrons, today they are lumped in the same genus. Now, azalea has become more of a common name within certain types of rhododendrons. People tend to think of rhododendrons as larger evergreen plants with big clusters of blooms. "Azaleas" are what people tend to associate with deciduous rhododendrons, and generally have smaller leaves and shorter plant habits.
Related: How Fast Do Encore Azaleas Grow?
More Varieties of Rhododendron
Rhododendron 'Robled' offers light pink flowers in spring, summer, and fall. It grows 3 feet tall and wide. Zones 7-9
A series of semi-evergreen azaleas that feature a re-blooming habit for season long color. Zones 6-9
Rhododendron 'Blue Diamond' is a dwarf evergreen rhododendron that bears violet-blue flowers. It grows 5 feet tall and wide. Zones 7-9
Beautiful cream variegated foliage sets this variety apart, with bright magenta flowers in the spring on dwarf plants that make great container plants. It grows 2-3 feet tall and wide. Zones 6-9.
Rhododendron 'Capistrano' is a compact, mounding selection, growing to 4 feet tall and wide, bearing trusses of frilled greenish-yellow flowers. Zones 6-8.
Rhododendron 'Cecile' grows vigorously to become a dense, 7-foot-tall and 7-foot-wide shrub with trusses of large, salmon-pink flowers. Zones 5-8.
Rhododendron 'Hydon Dawn' is one of the few rhododendrons that tolerates full sun. It has a low, compact habit to 5 feet tall and wide and bears clusters of small, clear pink flowers that fade to white. Zones 7-9.
Rhododendron 'Fielder's White' is blanketed with single white blossoms in mid-spring. Evergreen foliage complements the 3-inch-wide flowers on this variety. Zones 8-9.
Rhododendron 'Gibraltar' grows vigorously to 5 feet tall and wide, bearing bright orange flowers. Can tolerate full sun. Zones 5-8.
Rhododendron 'Karen' is a hardy evergreen azalea bearing purple flowers in spring. It grows 3 feet tall and wide. Zones 4-9.
A deciduous type azalea, it features bright orange blooms in spring on naked stems before the foliage emerges. It tops out around 4-5 feet tall. Zones 3-7.
Rhododendron 'Purple Dragon' features striking dark purple-red flowers that open at the branch tips in late spring. The shrub grows 3-4 feet tall and wide. Zones 7-9.
Rhododendron 'Hino Crimson' is a dwarf, densely growing azalea that produces bright red flowers. It grows 2 feet tall and wide. Zones 5-8.
Rhododendron yedoense poukhanense bears lilac to deep-rose funnel-shaped flowers in spring. In fall, leaves change to a gold or reddish purple. It grows 6 feet tall and wide. Zones 5-9
Rhododendron 'Nova Zembla' is a large evergreen shrub that bears trusses of deep red flowers with spotted throats. It grows 5 to 10 feet tall and wide. Zones 5-8.
Rhododendron 'Nuccio's Carnival' presents a profusion of large, single to semidouble magenta blossoms that add a burst of color to the landscape. Flowers are backed by rich green evergreen foliage. Zones 8-9.
Rhododendron 'Olga Mezitt' is an evergreen selection that produces small trusses of deep peach-pink flowers. The leaves redden in fall. It grows to 4 feet tall and wide. Zones 4-8.
Rhododendron 'Rose Queen', a cotton-candy-pink cultivar, has ruffled flowers in mid-spring. It grows 4-6 feet tall and wide. Zones 8-10.
Rhododendron 'Sun Chariot' is an upright, dense-growing spring-blooming variety that grows 6 feet tall and wide. It bears yellow blooms with orange blotches in large clusters. Zones 6-9.
Garden Plans for Rhododendron
A colorful alternative to the standard all-green landscape, this foundation planting mixes broad-leafed evergreen shrubs and a sculptural tree with flowering perennials and groundcovers.
Creating a garden around foliage is a surefire way to produce multiseason interest. While most garden beds focus on flowers, this mixed border emphasizes foliage plants of varying heights and textures, and throws flowers in for interest.