Autumn Lilac Encore azalea. (Photo by Allen Owings. Click on photo for downloadable image.)

Until recently, many home gardeners didn’t know much about the multi-season blooming potential of some of the newer azalea varieties.

“We have many groups of azaleas that provide spring and fall flowering in Louisiana,” says LSU AgCenter horticulturist Allen Owings. “These include the popular Robin Hill series, some of the Satsuki azaleas, GlennDale hybrid azaleas and others. The newest of the repeat-blooming azaleas is the popular Encore azaleas.”

Encore Azaleas debuted in the late 1990s and are the only patented azaleas to bloom in spring, summer and fall, Owings says.

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 azalea's “second act” opens when these buds begin blooming into full flower in mid-summer.

“This unique bloom season continues through the fall, and the curtain doesn’t drop until the onset of cold weather,” Owings says.

But, the show goes on. As an “encore,” these exceptional azaleas flower again 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,” Owings says.

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 azaleas perform best in full sun to light, filtered shade, Owings says. 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 exposure,” Owings says. “However, too much shade can result in skipped or significantly reduced bloom cycles.”

Owings recommends a raised bed to grow azaleas in most areas of Louisiana.

“Make sure you know the pH of your native soil and the landscape bed amendment material being used to make the raised bed,” he says. “Azaleas prefer a soil pH of 5.5, and a soil pH above 6.5 presents problems for azaleas.”

The new Encore azalea for 2010 is Autumn Lilac. Autumn Lilac has lavender flowers, and plants reach 4 feet tall, with a medium growth rate, Owings says.

“Encore azaleas are great plants for Louisiana landscapes,” Owings says. “With 24 varieties, you can select plants for small growth habit, along with intermediate and larger growth habits.

“We also have more flower colors available in Encore azaleas now than when the first few varieties were released,” he adds. “Reds, oranges, pink, blush, white, lavender and others are now available.”

Encore azaleas are one of the featured plants in the Margie Jenkins Azalea Garden at the LSU AgCenter’s Hammond Research Station in Hammond.

Other varieties in the Encore azalea family are:

– Autumn Amethyst – dark pink to purple, 4-foot height, medium growth rate.

– Autumn Angel – pure white, 3-foot height, medium growth rate.

– Autumn Belle – pale pink, 5-foot height, rapid growth rate.

– Autumn Carnation – medium pink, 4.5-foot height, medium growth rate.

– Autumn Carnival – medium pink, 3-foot height, slow growth rate.

– Autumn Cheer – medium pink, 3-foot height, slow growth rate.

– Autumn Chiffon – light pink with a dark pink center, 2.5-foot height, medium growth rate.

– Autumn Coral – soft coral pink with fuchsia center, 2.5-foot height, medium growth rate.

– Autumn Debutante – light pink, 4-foot height, medium growth rate.

– Autumn Embers – deep orange red, 3-foot height, medium growth rate.

– Autumn Empress – medium pink, 4-foot height, medium growth rate.

– Autumn Monarch – dark orange pink with red freckles, 5-foot height, rapid growth rate.

– Autumn Moonlight – white with yellow throat, 5-foot height, rapid growth rate.

– Autumn Princess – salmon pink, 3.5-foot height, medium growth rate.

– Autumn Rouge – deep red-pink, 4.5-foot height, rapid growth rate.

– Autumn Royalty – dark purple, 4.5-foot height, rapid growth rate.

– Autumn Ruby – ruby red, 2.5-foot height, medium growth rate.

– Autumn Sangria – dark pink, 4.5-foot height, rapid growth rate.

– Autumn Starlight – white with pink flecks, 3.5-foot height, rapid growth rate.

– Autumn Sundance – deep pink, 3.5-foot height, medium growth rate.

– Autumn Sunset – vivid orange-red, 4-foot height, medium growth rate.

– Autumn Sweetheart – soft pink to white with lavender freckles, 4-foot height, slow growth rate.

– Autumn Twist – white with purple stripes, 4.5-foot height, rapid growth rate.

Rick Bogren