AZALEAS – FOR FANTASTIC SPRING COLOR
by Keith C. Hansen, Extension Horticulturist, Smith Co. – Tyler, Texas
East Texas has the unique conditions which allows us to grow some of the most beautiful plants that a landscape can have – azaleas. The Azalea Trail in Tyler is an inspiring example of how well azaleas thrive in this area. Abundant shade, frequent rainfall, and sandy, well-drained, acid soils combine for the right ingredients for these spring-blooming beauties.
Spring is a good time to visit a local nursery if the Azalea Trail has you yearning for your own riot of color. It is certainly easier to make color selections when the plants are in bloom.
There are several major groups of azaleas with varying characteristics. Blooms range in color and size, and may be single or double. Azaleas have different growth habits from compact to large shrubs and the blooming season can vary from early to late spring. Some of the variety groups include Kurume, Southern Indica, Glendale, Robin Hill, Rutherford and Satsuki. Within each group there may be dozens of varieties to choose from.
Before you make a purchase, you should invest some time in developing a landscape plan. Plants selected for the landscape should enhance the beauty of the yard, not distract from it or become a maintenance chore. Pay attention to the ultimate size of the plants. The color of the blooms should compliment the colors of the house and other landscape plants. Also consider the soil, drainage and light exposure.
By proper selection, you could have a continuous display of azalea bloom from mid March through May. Azalea blooming season is usually classified as early, mid or late. Here is a tip if you do decide to extend the blooming season. Do not mix early and mid-season azaleas in the same bed. The fading blooms of the early flowers will detract from the newly opening blooms of the mid-season flowers.
Azaleas do best when grown in filtered sunlight and a highly organic soil. An ideal exposure would be under the branches of a large tree which drops its leaves in winter. An east or north facing side of the house or fence would also be a good location. However, dense, all day shade can result in leggy plants with skimpy blooms.
The soil must be well-drained. An ideal soil would be a sandy loam high in organic matter. If water tends to stand after a rain, or the soil has a high clay content, you will either need to select another site or make some modifications. If you have a less than ideal soil, you can still grow azaleas by making a mound or raised bed with a loose soil mix. Regardless of your soil, add large quantities of ground bark, compost, peat moss, or leaf mold to the soil to increase drainage and aeration.
Plant azaleas with the top of the root mass slightly above ground level. Never bury the crown or let the trunk be covered with soil or mulch. There is no need to dig the planting hole any deeper than the container. Azaleas are usually commercially grown in peat and may be root bound when purchased. Soak the root ball with water until no more bubbles emerge. Also, cut the sides of the root ball on three sides with a knife to encourage new root growth.
Although azaleas are sensitive to waterlogged soil, they have a very shallow root systems which can dry out rapidly under dry conditions. Always maintain a good layer of mulch, such as pine bark or needles, on the surface of the soil. Mulch not only maintains a more steady level of moisture, but also helps keep the azalea bed free of competing weeds. Do not mechanically cultivate the soil around azaleas. Instead, pull weeds by hand.
Water new plantings regularly, checking frequently to be sure you are not keeping the bed too wet. For established plants, be sure to water during the summer to prevent wilting during hot and dry weather. Thoroughly soak the soil in the root zone about once or twice a week.
The most important factor in fertilizing azaleas is to use only small amounts per application. Use cotton seed meal or any of the commercial acid-forming fertilizers made for acid-loving plants and follow directions. To be extra safe, cut the amounts in half and feed twice as often. Fertilize once growth begins in spring and no later than July. Above all, evenly distribute the fertilizer throughout the bed – never in concentrated piles.
Pruning can be done immediately after bloom if you need to cut back lanky shoots or encourage denser growth. Flower buds are formed in late summer, so no pruning should be done after that time.
In the summer, the newer leaves of azaleas may yellow with the veins remaining darker green. This is caused by a lack of iron and is called chlorosis. Iron chlorosis is common when plants are near sidewalks or building foundations where there is a higher concentration of lime from the mortar used in construction. Azaleas growing next to lawns which have been limed may also show iron deficiency. Most irrigation water is also alkaline. Iron chlorosis can be temporarily corrected by applying copperas or ferrous sulfate. Some leaves often turn yellow in late winter or early spring and is no cause for concern since this is a natural process of the plant shedding old leaves.
Finally, there are a few insects which may bother azaleas. Most common is the azalea lacebug. These feed on the underside of the leaves, giving leaves a gray, blanched or coarse stippled appearance. The underside of leaves become discolored by shiny black excrement and cast skins. Azaleas in sun, and under stress, are more prone to lace bugs.