Unlike our neighbors in Dallas, Austin or San Antonio, Tyler, along with the majority of East Texas, has unique conditions that allow us to grow beautiful azaleas. Our Azalea and Spring Flower Trail is a shining example of how well azaleas thrive in this area. Abundant filtered shade, regular rainfall and sandy loam, well-drained, acidic soils are the right ingredients for these eye-catching spring beauties.
Azaleas grow best in filtered sunlight and in a highly organic soil. An ideal exposure is under the branches of large deciduous trees or high canopy pines. An east- or north-facing side of the house or fence is also a good location. However, dense, all-day shade can result in spindly plants with sparse blooms.
The soil absolutely must be well-drained. An ideal soil is 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 soil 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. A good mix here is one-third sphagnum peat moss, one-third composted (black) pine bark and one-third clean sand. Regardless of your soil, add large quantities of ground bark, compost, peat moss or leaf mold to the soil to increase drainage and aeration.
Although azaleas are sensitive to waterlogged soils, they have very shallow root systems that can dry out rapidly under dry conditions. Always maintain a good layer of mulch, such as pine bark or pine 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 weed competition. Do not mechanically cultivate the soil around your azaleas. Pull them by hand instead. Always remember if you properly space your azaleas and mulch early on, they should spread to touch each other and choke out weeds themselves. This goes for all ornamental plantings. Any time sunlight hits bare soil, weeds will emerge.
Be sure to water your azaleas during the summer to prevent wilting during hot, dry weather. Thoroughly soak the soil in the root zone about once every week or two. Although azaleas most assuredly need irrigation during the summer months, most homeowners with sprinkler systems tend to water their lawns and shrubs too frequently. Deep soaking and less frequent sprinkling creates more extensive root systems, avoids root rot from water-logged soils and helps prevent diseases, which require a wet plant surface to germinate.
If you haven’t fertilized your azaleas yet, now is the time. The most important factor in fertilizing azaleas is to use small amounts per application. Use any of the commercial acid-forming azalea/camellia/gardenia fertilizers made for acid-loving plants, and follow directions on the label. The general rule for growing azaleas is to fertilize once growth begins in spring and no later than July. Above all, evenly distribute the fertilizer throughout the bed, never in concentrated piles, and water in after applying to make sure the fertilizer isn’t still on the foliage, which will cause burning.
Pruning is generally done the same time as fertilizing and mulching, most often just as the blooms fade. Generally, a light shearing is adequate. Shearing as the new growth emerges creates denser shrubs with even more blooms the following spring. You also may want to cut back lanky shoots to make your azaleas more uniform and less scraggly. Flower buds are formed in late summer, so no pruning should be done after that time. If you prune azaleas during the fall or winter, you will be removing the spring blooms.
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 that have been limed may also show iron deficiency. Most deep-well irrigation water also is alkaline. Iron chlorosis can be temporarily corrected by applying copperas or ferrous sulfate. Some leaves always turn yellow in late winter or early spring, and this is no cause for concern since this is a natural process of the plant shedding old leaves.
Finally, there are a few insects that may bother azaleas. Most common is the azalea lace bug. These feed on the underside of the leaves, giving leaves a gray, blanched or stippled appearance. The underside of the leaves becomes discolored by shiny black excrement and cast skins. Azaleas in direct sun, and under stress, are more prone to lace bugs. A granular application of a systemic insecticide containing Imidacloprid applied when the new growth is coming out is what the Ruby Mize Azalea Garden at SFA uses.
Azaleas are considered finicky, but if you have the right conditions and follow a few simple rules, they can be a great addition to our beautiful East Texas landscapes.
Greg Grant is the Smith County horticulturist for the Texas A&M AgriLife Extension Service. You can follow him on Facebook at “Greg Grant Gardens,” read his “Greg’s Ramblings” blog at arborgate.com and read his “In Greg’s Garden” in each issue of Texas Gardener magazine (texasgardener.com). For more information on local educational programming, go to smith.agrilife.org.