By LSU AgCenter Horticulturists Dan Gill, Kyle Huffstickler and Allen Owings
Encore azaleas have gathered consideration attention over the past 10 years, but we need to remember we had great, fall-flowering – sometimes referred to a multi-seasonal-flowering – azaleas before the Encore varieties. A great example is the Fashion azalea variety. But another azalea group widely planted in Louisiana for fall blooming is the Robin Hill hybrids.
These 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 begin growing these popular azaleas in the 1980s, and they continue to be used around the state today.
Varieties of the Robin Hill azaleas 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 sport of Watchet. It, however, is limited in availability for home gardeners right now. Some of the Robin Hill azaleas are being considered for Louisiana Super Plant status in the future.
These azaleas are evergreen, just as most of the traditional azaleas. Most Robin Hill varieties are slow- to medium-growth-rate plants and reach mature heights of 3-4 feet with an equal spread. Just as with other azaleas, they prefer a partial sun to partial shade and need acid, well-drained soil. After planting and during the establishment phase, irrigate as needed to aid in plant establishment.
Robin Hill azaleas should be pruned in spring within 2-4 weeks after the bloom cycle is completed. Fertilize in the spring also with a slow-release fertilizer after flowering. Mulch azalea beds with pine straw.
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 maples go great in azalea gardens as a smaller, signature, focal tree.