Autumn Sangria is one of the 29 varieties of Encore azaleas. (Photo by Allen Owings) Conversation Piece is a Robin Hill azalea variety that is a Louisiana Super Plant. (Photo by Allen Owings) News Release Distributed 10/03/14
By Allen Owings
LSU AgCenter horticulturist
HAMMOND, La. – It’s getting to the time of year when multiseason-blooming azaleas will begin their fall floral displays. Popular fall-flowering azaleas include the Robin Hill and Encore types.
Robin Hill azaleas resulted from hybridization work conducted by Robert Gartrell of New Jersey in the 1950s and 1960s. These have large flowers on hardy plants; good form and foliage, and an intermediate growth size. Other main attributes are cold hardiness and an extended blooming season.
Most years, Robin Hill azalea varieties will bloom for six months in Louisiana. You can get two to three months of bloom in spring and another three to four months in late summer through early winter. This group includes 70 varieties with 10-12 readily available in Louisiana. Louisiana nursery growers began growing these popular azaleas in the 1980s, and they continue to be used around the state today.
Robin Hill azalea varieties for Louisiana include Conversation Piece, Watchet, Nancy of Robin Hill, White Moon, Dorothy Rees, Roddy, Gwenda, Sir Robert and Sherbrook. Flower colors vary from white to pink, blush, bicolors and more. The newest variety is Freddy, a beautiful white-flowering natural mutation of Watchet. It, however, is limited in availability for home gardeners right now. Some Robin Hill azaleas are being considered for Louisiana Super Plant status in the future.
In addition to Robin Hill azaleas, you may want to try Encore azaleas. Many of the Encore azaleas now have improved cold hardiness (normally not a problem in Louisiana), sun tolerance and lacebug resistance. Encore azaleas bloom three seasons – spring, summer and fall. New Encore varieties include Autumn Sunburst, Autumn Lily, Autumn Jewel and Autumn Ivory.
Encore azaleas were developed by Louisiana nursery grower and plant breeder Robert E. "Buddy" Lee of Independence. 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 and Robin Hill azaleas are evergreen, just as most traditional azaleas. Most varieties have a slow-to-medium growth rate and reach mature heights of 3-4 feet with an equal spread. A few of the Encore varieties produce larger-growing plants. Just as with other azaleas, they prefer a partial sun to partial shade and need acidic, well-drained soil. After planting and during the establishment phase, irrigate as needed to aid in plant establishment.
Azaleas blooming more than once a year should be pruned in spring within 2-4 weeks after the bloom cycle is completed. Fertilize in spring also with a slow-release fertilizer after flowering. Mulch azalea beds with pine straw.
Azaleas need a partial sun to partial shaded planting location. Plants do best in well-drained raised landscape beds. A soil pH of 5.5 is ideal. Plants should be mulched with pine straw. Uniformity in soil moisture is important.
The unique multiseason-blooming Robin Hill and Encore azaleas are available at many Louisiana garden centers. You can see many azaleas, including both these types and other spring- and fall-flowering varieties, in the Margie Jenkins Azalea Garden at the LSU AgCenter Hammond Research Station in Hammond, Louisiana.
Intermediate-growing azaleas, like Robin Hill varieties, work well in foundation plantings with Knock Out roses, Indian hawthorn, loropetalums and other popular shrubs. They are also great for use in beds underneath trees as a companion plant with hydrangeas and native shrubs. Including small-growing trees, such as redbuds and Japanese magnolias, add appeal to an azalea planting, and Japanese maple goes great in an azalea garden as a smaller, signature, focal tree.
You can see more about work being done in landscape horticulture by visiting the LSU AgCenter Hammond Research Station website. Also, like us on Facebook. You can find an abundance of landscape information for both home gardeners and industry professionals at both sites.
Rick Bogren