LSU AgCenter Horticulturist
Azaleas are ubiquitous in Southern gardens — and for good reason. Each spring, the azalea bloom is a sight to see. Some travelers make trips to the South just to see this spectacular display of flowers, much like Southerners head north to enjoy the fall foliage change.
By far, the South’s most popular flowering shrub is the Southern Indica azaleas (Rhododendron indicum) from Japan. One of the oldest collections was started in the early 1800s at Magnolia Gardens near Charleston, South Carolina.
One azalea that does not receive the attention it so deserves is the native azalea, also known as honeysuckle or deciduous azalea. I affectionately call it the wild azalea. It reminds me of when I was a kid taking hikes on the Wild Azalea Trail, the longest trail in Louisiana. It covers 26 miles in the Kisatchie National Forest just outside of Alexandria, and likely was named for the native azaleas found there.
There are 17 species of native azaleas in the United States, and they are divided into groups based on flower color — typically pink, orange to red or white. You can learn more about each species at the Azalea Society of America’s website www.azaleas.org.
Unlike the evergreen azaleas from Asia that we are all accustomed to, native azaleas drop their leaves each winter. Before leafing out in the spring, flowers arise on naked branches, providing a display of gorgeously colored and highly fragrant, honeysuckle-like flowers.
The funnel-shaped flowers form in clusters and attract butterflies and other pollinators to the garden. The flowers appear in early spring, with others having blooms into the early summer. Plant native azaleas in an area that gets filtered sun, as they are accustomed to cooler areas such as piney woodland areas in the forest. Choose a site with morning sun and afternoon shade.
All azaleas require an acidic soil for optimal growth. Be sure that the site that you plant has a pH of 5.0 to 6.0. You can lower the pH of the soil by amending with sulfur. The amendment most often applied is elemental sulfur. When elemental sulfur reacts with water, sulfuric acid is the resulting product, thereby dropping the pH. Other available options include ammonium sulfate, ammonium nitrate, aluminum sulfate and urea. Follow the product label instructions for application rate.
When incorporating native azaleas into the landscape, be sure to keep in mind that their growth habit is more upright than the rounded habit of evergreen azaleas. It can grow to upwards of 15 feet and as wide as 6 to 8 feet at maturity. It can be trimmed to help keep its shape, or you can let this azalea grow wildly.
There are no major pest or disease concerns, but pH is particularly important. You can fertilize in the springtime with a slow-release fertilizer. Look for fertilizers specifically for acid-loving plants such as azaleas and camellias.
Some of the most commonly found native azaleas in the local retail garden centers are the Piedmont azalea (Rhododendron canescens) with a light pink fragrant flower; the pinxterbloom azalea (Rhododendron periclymenoides) that prefers more northern climates in USDA zones 4 to 8 and is more dwarf-like with light pink to lavender blooms; and the Florida flame azalea (Rhododendron austrinum) with yellow-orange-gold blooms and growing up to 8 to 10 feet tall in USDA hardiness zones 6 to 9.
To see a native azalea, you no longer need to get off the beaten path or visit the forest. You can find native azaleas at many local retail garden centers and incorporate a piece of the wild forest into your garden.
Florida flame azalea has beautiful golden-orange flowers. Photo by Bob Mirabello/LSU AgCenter
Piedmont azalea has a light pink, fragrant flower that pollinators love. LSU AgCenter file photo by Dan Gill
Native azaleas’ tube-shaped flowers attract many pollinators such as butterflies and hummingbirds. Photo by Heather Kirk-Ballard/LSU AgCenter
Evergreen azaleas are an iconic flowering shrub in the southeastern United States. Photo by Heather Kirk-Ballard/LSU AgCenter