Hybrid Rhododendrons A Mystery Solved
Today Atlanta gardeners grow rhododendrons easily and successfully. However, a few years hack, most area gardeners thought rhododendron s almost impossible to grow. Observation demonstrated that the ones which lived and flourished were planted on slope, accidentally providing the necessary good drainage. Plantsmen like the late Frank Smith recognized that rhododendron planted in our red clay was being sentenced to die by drowning or root rot. Smith introduced an easy, above ground planting method, refined by current rhododendron specialists, that works.
Planted correctly for Atlanta conditions, rhododendrons rarely need further care, except watering at appropriate times. Most rhododendrons grow and bloom in filtered sun. Some tolerate sunny situations. In dense shade, rhododendron rarely bloom.
Ray Goza’s Guidelines for Successful Rhododendron Growing in Atlanta
BUYING. Attempt to purchase plants that have been grown in hot, humid areas for at least one summer. Plants shipped, into Atlanta mountainous or cool areas may develop root rot. It's preferable to select plants growing in pine bark, not heavy west coast soils. An alterative is to hose off all soil from the roots before planting. Choose plants sufficient roots to nourish and support plant's top growth. Buy recommended named plants.
SELECTING A SITE. Select a planting site with filtered sun or high shade, adequate light (neither all day full sun nor dense shade), north or east exposure, good drainage, and good air flow (the plant should not be crowded by other shrubs or structures).
PLANTING. Plant rhododendrons only in the spring, fall or winter but avoid times of extreme temperatures. Plant very shallow Dig a hole 4˘ ˘ deep and 3˘ in diameter. Discard the soil. Place mini pine bark nuggets about 1˘ ˘ deep over entire bottom of hole.
Remove plant from container and loosen root ball if possible, spread roots Place plant in center of hole, wounding pine hark around root system border out to perimeter of hole. Do not place pine bark on top of root system. With your hands, firm up bark around roots. This helps hold the plant upright and secure. Usually it will take 9 cu ft. of bark per plant. Place a mulch of 4-5" of pine straw over root system and all exposed pine hark. Do not allow pine straw to touch stem. Water well during the next week.
Lewis Shortt’s Typical Planting Schematic
To ensure root-rot free years to come, Lewis Shortt prefers a slightly deeper hole filled with a 50/50 mixture of coarse sand and uncomposted pine hark for 6" below the root ball.
Fertilizing at Planting
Local commercial grower Ray Goza recommends no fertilizer at planting. Lewis Shortt adds 1/2 cup of 0-14-14 per three-gallon plant Shortt also adds a generous cup of gypsum, 1/2 cup ferrous sulfate and 1/2 cup Epsom salts at planting. He says these additives release necessary elements for the rhododendron.
Give root system a deep soaking for a short period of time. According to weather conditions, a rhododendron may need water every other day the first summer and fall. With normal rainfall,an established plant requires little watering in summer and fall and none in winter. During
periods of severe drought any season of the year, water rhododendron. To prevent disease, Ray Goza applies water in the daytime so foliage can before nightfall.
Ray Goza fertilizes in January at the rate of 2 tablespoons of Nursery Special or azalea/rhododendron fertilizer per 2’ rhododendron height sprinkled on top of pine straw mulch. Lewis Shortt prefers to fertilize immediately following blooming,hut only if the plant appears cm distressed or us foliage has poor color. Both growers get excellent results.
Insect and Disease Control
These are minor problems in rhododendrons. Chewing insects can be controlled by spraying the ground and plantwith Orthene tree and ornamental chemical. Leaf spot and Fungus require spraying with the systemic Daconil, sometimes as often as every two weeks.
Tips from the Experts
Lewis Shortt suggests buying the largest rhododendrons you can afford. In his experience, they adjust better to transplanting than small Ones, and prove hardier to temperature extremes.
Remove dead or spent flowers from rhododendrons.
Remember the rhododendrons, unlike most other shrubs or perennials; do not always from bloom buds every year.
Forinformation on the local Azalea Chapter of the American Rhododendron Society contact the Atlanta Botanical Garden.
Anyone considering using chemicals should contact their county agent.