John Young, Gill, Daniel J., Owings, Allen D. | 11/13/2008 9:51:10 PM
By LSU AgCenter Horticulturists
Not so long ago, nursery and landscape professionals, along with the vast majority of home gardeners, were not fully aware of the multiseason blooming potential of many azalea varieties.
Now, professionals and home gardeners alike are learning that several groups of azaleas provide both spring and fall flowering in Louisiana.
These azalea types include the popular Robin Hill azaleas, some of the Satsuki azaleas, Glenn Dale hybrid azaleas and others. The newest group of repeat-blooming azaleas is the popular Encore azalea.
Encores debuted in the late 1990s and are the only patented brand of azaleas to bloom in spring, late summer and fall. Some 23 varieties are now available in a number of different colors. They begin their performance with the spring flowering season. Once this first act of blooming concludes, new shoots begin to grow and set buds. The “encore performance” happens when these buds begin blooming in mid- to late summer.
This unique blooming cycle continues through the fall – the curtain dropping with the onset of cold weather. A new show begins again when these exceptional azaleas flower with traditional spring azaleas, and the process starts over. In some years in South Louisiana, you get blooms on some varieties of Encore azaleas for eight months, although four to six months is more common.
Encore azaleas were developed by Louisiana nursery grower and plant breeder Robert E. "Buddy" Lee of Independence, La. Lee first envisioned Encore Azaleas in the early 1980s when he found a tray of azalea cuttings blooming in the summer sun at his small Louisiana azalea nursery. Inspired, he began crossing traditional spring-blooming azaleas with the rare Taiwanese summer-blooming azalea, Rhododendron oldhamii. After many years, the Encore azaleas were ready for their gardening debut.
Encore azaleas perform best in full sun to light, filtered shade. In Louisiana, most azaleas prefer morning sun with afternoon filtered shade. A minimum of four to six hours of direct sunlight per day is required for good flowering. Care must be taken to prevent exposure to drought or other heat-related stress conditions associated with full-sun exposures. Too much shade, however, can result in skipped or significantly reduced blooming.
Unless your site has excellent drainage, a raised bed is best for growing azaleas in most areas of Louisiana. Make sure you know the pH of the soil in the bed where you plant azaleas. Azaleas prefer a soil pH of 5.5. A soil pH above 6.5 may present problems for azaleas.
Water azaleas well when you first plant them. Keep soil moist but avoid creating a constantly wet soil with frequent watering. Monitor watering carefully. New azaleas will die quickly if the soil dries excessively. Azaleas should not need regular watering after the first year except during periods of drought.
Fertilize with the recommended levels of a slow-release fertilizer in the spring after flowering is complete. Ironite or other fertilizers with micronutrients may help azaleas keep a greener color. Light fertilization may also be needed in mid- to late summer.
Like other hardy landscape shrubs, azaleas do well when they are planted in the fall. Garden centers have the most azaleas available in the spring, but fall is the best time to plant. Fall planting allows the plants to establish with less stress, and new roots produced in the fall will help the azalea flourish in the next growing season. Although less watering is necessary during the winter season, do not allow the roots to become dry. A 2- to 3-inch layer of pine straw is an excellent mulch to help maintain soil moisture and aid in weed suppression.
A frequent question is when to prune multiseason azaleas. Most Encores and other types require very little pruning to retain good form and maintain the desired size. If you think your azaleas need pruning, do so immediately after the spring flowering. Light pruning of more established plants at that time can stimulate growth and flowering.
Encore azaleas are great plants for Louisiana landscapes. With 23 varieties, you can select plants for small growth habit, along with intermediate and larger growth habits. Colors are available to suit virtually any color scheme, including reds, oranges, pink, blush, white, purple, lavender. Some types even produce different colored flowers on the same plant.
The LSU AgCenter has planted Encore azaleas at LaHouse in Baton Rouge and test plots at the Burden Center in Baton Rouge and at the Hammond Research Station in Hammond.
Come to LaHouse in Baton Rouge to see sustainable landscape practices in action. LaHouse is located near the intersection of Burbank Drive and Nicholson Drive (La. Highway 30) in Baton Rouge across the street from the new LSU baseball stadium. For more information, go to www.louisianahouse.org and www.lsuagcenter.com/lyn.
Dan Gill at (225) 578-2222 or email@example.com
Allen D. Owings at (985) 543-4125 or firstname.lastname@example.org
John Young at (225) 578-2415 or (225) 578-2222 or JoYoung@agcenter.lsu.edu
Editor: Mark Claesgens at (225) 578-2939 or email@example.com