Azaleas are a traditional part of Southern landscapes. University of Georgia Cooperative Extension experts say prune azaleas now, after they have bloomed, to allow the plants to prepare for blooming next year.
In Georgia, many azaleas begin to set flower buds in July. Therefore, pruning after early July may reduce next year's flower production. Compact plants can be maintained with minimal effect on flower production.
Two pruning techniques or types of cuts are used: thinning cuts and heading cuts.
Thinning refers to the complete removal of branches back to another branch or main trunk. Thinning is used to remove leggy branches that extend beyond the canopy of the plant, to reduce the size of the plant or to remove any damaged or diseased wood. Thinning can be done any time of the year without significant impact on flowering, growth or cold hardiness.
Heading refers to the cutting back of a branch, not necessarily to a side branch. Vigorous new shoots will emerge within 6 inches of the pruning cut. Heading is usually done with three goals in mind: to reduce the size of the plant, to increase the number of branches or to rejuvenate old, overgrown plants. Severe pruning of old, overgrown plants to within 6 to 12 inches of ground level is a common type of heading.
New shoots emerging from the old stems should be thinned out and headed back to encourage branching and a full canopy. The best time to make heading cuts is just after the plant flowers out in the spring. This allows sufficient time for the new growth to mature and harden-off before winter and for flower buds to form in late summer for the following year.
Depends on size
Young plants should be pruned about six weeks after blooming and thereafter as branches develop sufficient length. However, do not prune later than the first week in July, so plants will have time to initiate new growth and bloom buds.
Small azalea plants should be pruned several times during the growing season to develop well-branched plants. This involves pruning the tips of the new, individual branches after five or six inches of new growth has been produced. This pruning not only results in a compact, well-branched plant, but also one that will produce many more blooms.
Azaleas often become entirely too large for the area they occupy, especially when they are used as foundation plants. If this happens, cut back the large plants to 12 inches above the ground level in early spring. Growth of the new stems and leaves will be quite rapid once new growth buds appear on the stem. Keep the soil moist during the period after severe pruning.
Azalea limbs are killed occasionally by fungus diseases or by freezing weather, which kills the conducting tissue and causes the bark to split. These limbs should be pruned out with small hand pruning shears. Heavier loping shears should be used for cutting out larger stems. Cut the diseased or dead limbs back far enough to expose live wood. If flecks of diseased or dead wood remain visible inside the cut surface, continue to cut farther back on the stem to expose only healthy wood.
Azalea plants often produce a few tall shoots relatively late in the season that do not initiate flower buds. These shoots not only detract from the general shape of the plant, but also fail to branch properly the following year. Cut these tall shoots out during late October or early November.
For more information on pruning landscape plants, search the UGA College of Agricultural and Environmental Sciences publication website at www.caes.uga.edu/publications.