The azaleas are showing off right now, putting on their annual spring spectacular despite the recent rain, ice storm and extended freezing temperatures.

Luckily, these flowers, which are the South's most popular flowering shrub, are cold hardy.

Spring is a great time to plant azaleas.

In general, azaleas prefer an acidic soil with a pH of 5.0 to 6.0 that is rich in organic matter and well drained. Check the soil pH and amend with elemental sulfur, aluminum sulfate or ammonium sulfate to help bring the pH down if needed. Fertilize in late winter and early spring for the best blooms and greener foliage.

Azaleas have a broad, mounding growth habit and grow to an average size of 6 feet high-by-6 feet wide. There are some varieties that are more compact at 2 feet by 2 feet, and others grow up to 10 feet by 10 feet.

They can be grown in full sun, but prefer partial shade, and naturally grow as an understory plant to pine trees.

Be sure to mulch your beds to conserve soil moisture, suppress weeds and provide a source of organic matter.

Prune very soon after flowers have bloomed, removing a small amount of wood annually to keep plants compact and thin out tall, spindly stems. Buds are set on old wood, so do not prune in summer, fall or winter, or you will miss next year’s show.

Azaleas do have some issues, but they are easily controlled if caught early and preventative measures are taken. Some common pests include lace bugs, bark scale and spider mites. Petal blight, leaf gall and root rot are common diseases.

Look for bronzing on older leaves as a sign of spider mites and mottling or tiny brown spots on the leaf when lace bugs are present. Lace bugs are found on the underside of leaves, making them more difficult to control. They often cause problems in late winter and early spring.

Use a systemic insecticide with the active ingredient imidacloprid to control mites, scale and lace bugs. You must re-treat in seven to 10 days to kill newly hatched pests.

Many common diseases of azaleas are caused by fungal pathogens which can be reduced with proper drainage.

Most types of azaleas bloom in the spring, but some varieties have become popular because they bloom later. And there are many colors from which to choose.

Azalea breeders have been selecting and breeding these plants for hundreds of years, so today there are thousands of different cultivars of azaleas. 

Louisiana boasts its own famous breeder, Buddy Lee, of Folsom. He is responsible for one of the most popular repeat-blooming azalea varieties in America, called Encore, which has 33 varieties, including Autumn Embers, Autumn Royalty, Autumn Fire, Autumn Twist and Autumn Princess. Blooming in spring, summer and fall, researchers at the LSU AgCenter determined an average of 21 to 32 weeks of bloom.

Native azaleas are deciduous, and attract hummingbirds, butterflies and other pollinators with their colorful, nectar-rich flowers. Flame of Florida azalea (Rhododendron austrinum) and honeysuckle azalea (Rhododendron canescens) are two found readily at local nurseries.

Also look for the Louisiana Super Plant pick Conversation Piece azalea, which is noted for its large pink flowers that are nearly 4 inches across. They are repeat bloomers and cold hardy.

Indian azalea flowers can grow anywhere from 2 to 3½ inches across for the most grandiose display. Formosa, Dixie Beauty, George L. Tabor and Mrs. G.G. Gerbing are by far the stars of this category. There are several other varieties of Indian azaleas, including Daphne Salmon, Fielder’s White, Judge Solomon, President Clay, Pride of Mobile and Southern Charm.

The Kurume azaleas are dwarf azaleas growing to 4 to 6 feet in height by 3 feet in width at a slower, denser rate. Flowers are only 1 to 2 inches across. Popular varieties are Christmas Cheer, Coral Bells, Hershey’s Red, H.H. Hume, Hinodegiri and Snow.

The Satsuki azaleas bloom later in spring, in April and May. Popular varieties are Gyokushin, Pink Gumpo, Pink Macrantha, Red Gumpo, White Gumpo and Hardy Gardenia.

For a complete list, description and details of various varieties search for “azaleas publication 1295” at lsuagcenter.com.


Email questions to gardennews@agcenter.lsu.edu.