Azalea and Rhododendron

Trouble-free shrubs with huge flower clusters, some blooming until frost

Rhododendron is a huge genus of flowering shrubs, known as azaleas and rhododendrons. These shrubs can be evergreen or deciduous. They are some of the easiest shrubs to grow, and as such, are some of the most popular for landscapes. Azaleas and rhododendrons are very similar, but there are minor differences. In general, azaleas tend to be slightly smaller. They have funnel-shaped flowers with 5 stamens and scaleless, but often hairy, leaves. Rhododendrons have bell-shaped flowers with 10 or more stamens, and their leaves are larger with scaly or dotted undersides. Both produce huge flower clusters, in shades of white, yellow, orange, pink, purple, or red, that bees, butterflies, and hummingbirds adore. Most bloom in spring, but now some varieties flower until first frost.

Azaleas and rhododendrons are versatile shrubs with many uses in the landscape, but proper placement and soil pH are very important. These shrubs typically have a rounded habit and grow 6 to 10 feet tall and 5 to 8 feet wide. They make lovely specimens but are shown to best effect massed or grouped and are exceptional understory shrubs in naturalized areas. To grow their best, rhododendrons and azaleas require a location with dappled or morning sun and acidic soil, preferably with a pH between 5 and 5.5. Any compacted soil should be amended with organic matter before planting. Although previously known as Southern plants, now some varieties are cold hardy as far north as Zone 3.

Sweet azaleas, smooth azaleas, tree azaleas, flame azaleas, and mountain azaleas are frequently grown in home gardens. In addition, the pinxterbloom azalea and the swamp azalea, both native shrubs, endemic to eastern U.S., are also gardeners' favorites.