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Varieties of Azaleas and Rhododendrons

Catawba Rhododendron, PJM Rhododendron and a Stunning Azalea Plant

By David Beaulieu, About.com

Catawba Rhododendron

Catawba Rhododendron

Courtesy Missouri Botanical Garden

Ever wondered what the difference is between azaleas and rhododendrons (sometimes misspelled "rhododendrums")? Landscaping enthusiasts seem content to group all the varieties together -- both in their vocabulary and in their yards -- as long as they get to enjoy the beautiful pictures these long-time gardening favorites paint on their landscapes! But for those curious about what distinguishes azaleas from rhododendrons, the information will be provided on Page 2. The present page focuses, rather, on introducing a few varieties of these spectacular flowering bushes -- through pictures and brief descriptions. Information will be provided regarding the care for azaleas and rhododendrons on Pages 3 and 4.

Two Popular Varieties of Rhododendron Bush

The Catawba rhododendron variety (Rhododendron catawbiense) is a broadleaf evergreen bush that has dark green, leathery foliage, and spring flowers that are great for attracting hummingbirds. This rhododendron shrub is easy to transplant, but it does require an acidic soil and prefers a shady location. Flowers can be white, lavender, rose or the red that hummingbirds so love. Catawba rhododendron bushes can reach a height of 6'-8' with a spread of 4'-6'. A rhododendron display is most effective when rhododendron bushes are massed together. Warning: toxic -- do not allow children to ingest any of the azaleas or rhododendrons. Zones 4-8. See photo #1 above.

P.J.M. rhododendron (Rhododendron x ‘P.J.M.’) is considered perhaps the hardiest of the rhododendrons, in terms of withstanding not only cold, but also heat and sun. Varieties of P.J.M are available with either pinkish-lavender or white flowers. Because it flowers early, blooms are susceptible to frost damage. The green of its summer foliage yields to a mahogany color in winter -- a plus for those seeking year-round interest on the landscape.

The flowers of P.J.M. rhododendrons are smaller than those of Catawba rhododendron. P.J.M rhododendron’s overall size is also smaller, as it reaches approximately 4’ x 4’ at maturity. Zones 4-8. Good choice for foundation plantings and rock gardens. For a picture of this spring-blooming favorite, see photo #2 above (accessed by clicking on photo #1 to open the mini-photo gallery).

A Pretty Picture -- Whatever You Call This Azalea....

The "Stewartsonian" azalea (Rhododendron x Gable 'Stewartsonian') is an evergreen suitable for growing in zones 5-8. Dimensions approximately 5' x 5'. Grows best in part shade and, like most azaleas and rhododendrons, acidic, well-drained soil. Apply an organic mulch to protect its shallow roots from water-loss and extremes in soil temperature.

Developed by Joseph Gable of Stewartstown, Pennsylvania, people can't seem to make up their minds on the spelling of its name. I've seen it listed both as "Stewartstonian" and "Stewartsonian." This is another bush whose green summer foliage yields to a mahogany color in winter, making it an ideal candidate to provide year-round interest on the landscape. Also another good choice for foundation plantings, since it remains a relatively compact plant. For a picture of this azalea shrub, see photo #3 above (accessed by clicking on photo #1 to open the mini-photo gallery).

On Page 2 we’ll explore the difference between azaleas and rhododendrons. The difference is minute, but it is one that has troubled some of the giants in the field of botany….

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