Taking Care of Your Rhododendrons
ven though rhododendrons aren't wicked, they often get sent to a hot, hot place--the typical Southern garden. There these beautiful mountain natives spend brief, tormented lives dreaming of cool, misty summers and soil that drains. Will anyone come to their rescue?
You bet. His name is Robert Rollings. He lives in Saluda, South Carolina, just a stone's throw from Columbia. Saluda's summer is hotter than Jessica Alba. Its soil contains more clay than Clay Aiken. Yet 65 rhododendrons have thrived in Robert's garden for years. Here's how he does it.
photo: 'English Roseum' blooms greet Robert and Jessie Rollings each spring.
Location, Location, Location
The Right Site
Rhododendrons prefer growing on a slope, where water quickly drains away. If your yard is level, plant in a raised bed. Robert tills the soil and then uses crossties cut in half to make a 4-foot-square raised bed for each plant. When filled with soil, the bed raises the roots above ground level so they won't sit in water after a heavy rain.
The Right Soil
This is critical. Rhododendrons rot and die if planted in heavy clay. They need loose, acid (pH lower than 6.5) soil that contains lots of organic matter. Robert uses a soil mix consisting of 2 parts finely ground bark and 1 part sand. Before planting in spring, he slips a new plant out of its pot, soaks the root-ball, and then uses his fingers to gently remove the soil from the bottom of the root-ball while preserving the roots, leaving the root-ball only 6 to 8 inches high. Next, he spreads the roots in the hole and backfills with soil mix to the top of the root-ball. "I don't want the roots to go down," he explains. "I want them to go out."
Let There Be Light
The Right Light
Dappled sunlight and shade provided by tall pines and hardwoods with their lower branches removed works best. "You need a certain amount of sunlight to get blooms," he notes. "If it's too shady, you'll get fine foliage but no blossoms."
The Right Food
Use an azalea/rhododendron fertilizer at the rate recommended on the bag. Feed immediately after blooming, not before.
Water and Mulch
Rhododendrons have shallow roots. Robert suggests watering in a band around each plant, starting at the trunk and running out 80% of the way to the dripline (the point where the widest branches reach). Water until you've wet the soil 6 inches deep. Cover the roots with several inches of mulch to keep the soil cool and moist. How can you tell when a plant needs water? "If it's late in the day in summer and the leaves are drooping and then the next morning they're straightened out, the plant is fine," he says. "But if leaves are still wilted the next morning, water."
The Right Selections
Never buy rhododendrons labeled simply by color. Choose named selections that are proven to take Southern heat and humidity. A great mail-order source is RareFind Nursery, www.rarefindnursery.com. Here are some of Robert's favorite selections.
- 'Anah Kruschke'--lavender-blue to reddish-purple
- 'Anna Rose Whitney'--deep pink
- 'Ben Moseley'--purplish-pink with a dark blotch
- 'Blue Ensign'--lilac-blue with a dark blotch
- 'Calsap'--lavender-white with a dark purple blotch
- 'Caroline'--light pink
- 'Cynthia'--rosy crimson, Robert's top pick
- 'English Roseum'--pink
- 'Janet Blair'--pink and cream with a yellow blotch
- 'Scintillation'--light pink with a yellow blotch
- 'Wheatley'--rose pink
"Rx for Rhododendrons" is from the April 2008 issue of Southern Living.