Smith County horticulturist
Azaleas do best in part-sun, part-shady locations, in well-drained soils that are moderately acidic with a pH of around 5.5. They thrive when the soil is generously amended with a finished composted product, and kept evenly moist during the growing season. That last part can be more challenging in the summer time, but with a drip or microspray irrigation system, coupled with several inches of mulch on the surface of the soil, azaleas will thrive and remain healthy for many years.
There are thousands of varieties of azaleas, and choosing which ones to grow might be a challenge. Evergreen azaleas are grouped in hybrid classes, and can be further broken down in to their blooming season. They may be early-, mid- or late-season bloomers, or somewhere in between.
Earlier this year it looked like the early azalea blooming season, for which the Trail is known, might start a little early with the warm temperatures in late January and early February. But thanks to cooler, cloudy weather, the pace of spring slowed, and now everything is ready to burst forth in color with warm, sunny days.
Some of the types of azaleas you will see during the time of the Azalea Trail include the smaller statured Kurume hybrids, such as Hino de Giri, Coral Bells and Snow. Then there are the larger the Southern Indica types like Judge Solomon, Mrs. G.G. Gerbing, Formosa or Pride of Mobile. Red Ruffles, Hampton Beauty, Delaware Valley White and Fashion are among the many other varieties blooming in early spring.
Other types bloom a bit later in April, such as the Glenn Dale and Robin Hill hybrids. Then in May, the Satsuki varieties extend the show with their large, showy blooms.
They are not difficult to kill, but insecticide products sprayed must reach the underside of the foliage, requiring good pressure from your sprayer. This can be challenging for large plants with dense foliage.
Azadirachtin, insecticidal soap, horticultural oils, neem oil, or spinosad are low-toxicity products that will temporarily control lace bugs if applied thoroughly to cover the underside of leaves where adults and nymphs occur.
There are a couple of soil-applied systemic insecticides that will do a good job of controlling azalea lace bugs for most of growing season. Look for the active ingredient imidacloprid, which is found in many products labeled for tree and shrub insect control, and dinotefuran, sold as Safari. Start early in the growing season for best control results. While insecticides will not restore the damaged foliage, they can reduce or prevent further damage.
Keith Hansen is Smith County horticulturist with the Texas A&M AgriLife Extension Service. His web page is http://EastTexasGardening.tamu.edu His blog is http://agrilife.org/etg