Few landscape shrubs are as widely celebrated and anticipated in the spring garden as azaleas and rhododendrons.Their showy, exuberant displays of color excite the senses and have a way of taking center stage in just about any landscape.The billowing masses of colorful, mature azaleas and rhododendrons in the background clearly competed with the golfers for the viewer’s attention.In the United States and in Asia, countless azalea festivals are timed to occur when the shrubs are at their showiest.Just about every public botanical garden this side of the Mississippi and even beyond has an azalea and rhododendron collection.Azaleas and rhododendrons are native to Asia, Europe and North America and may be either deciduous or evergreen.All evergreen species originally came from Asia and generally tend to be hardy only to Zone 6.Bear in mind, however, that these are GENERAL characteristics only and may not hold true for every hybrid or species:.Color of flowers – Azaleas come in many shades of white, cream, pink, red, lavender, purple, orange and yellow Their color palette is much broader than that of rhododendrons, which tend to be restricted to white, orchid pink, purple, red and occasionally yellow.Thanks to the efforts of both American and Asian hybridizers, thousands of azalea and rhododendron species are available commercially.Azaleas tend to average about three-to-five feet in height and width, but bear in mind while some cultivars may be smaller, a lot of them can grow quite large.There has been a resurgence of interest in azaleas over the past decade or so due to the introduction of the Encore series of re-blooming species.Should you choose a reblooming azalea for your garden, keep in mind how the color will work (or not) with your landscape throughout the entire growing season.If the pH is too high, apply a small amount of agricultural sulfur or iron sulfate .See Virginia Cooperative Extension Publication 426-602, “Growing Azaleas and Rhododendrons,” for guidance on fertilization (https://pubs.ext.vt.edu/426-602/426-602.html).See Virginia Cooperative Extension Publication 426-602, “Growing Azaleas and Rhododendrons,” for guidance on fertilization (https://pubs.ext.vt.edu/426-602/426-602.html).But if a soil test indicates the need for fertilizer, use one that is especially formulated for azaleas and rhododendrons and apply carefully to avoid damaging the fine roots.In my experience, lacebugs tend to attack azaleas that are planted in full sun.Diseases — Azaleas are subject to leafy gall, which can be destructive to the leaves in the early spring.Azaleas and rhododendrons are also subject to phytophthora root rot in moist, hot conditions.Location – choose a site sloping to the north or to the east in order to protect the plant from drying south or west winds.Winter winds tend to evaporate water from the leaves of evergreen azaleas and rhododendrons.Soil Preparation — Azaleas and rhododendrons have very delicate, shallow root systems and struggle to penetrate our heavy Virginia red clay.Azaleas and rhododendrons are so popular on the east coast that it is impossible to name all the collections that are available without expanding this article to an unmanageable length.Their collection is scattered throughout the garden, so wear comfortable walking shoes if you visit.Former arboretum Director Benjamin Y.
Edward R. Forte
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