Pruning Evergreen Azaleas:
It is all too evident that a significant percentage of evergreen azalea pruning problems are caused by the average gardener who purchases two or three young plants then puts them in a small space in the garden, often in a rockery area, only to find that in a relatively few years they have completely outgrown their allotted position. The gardener’s face is often a picture when they are told that at this age these plants are mere youngsters who can have many years growth ahead of them before reaching maturity. It is a myth that azaleas are ideal plants for the very small gardens of suburban towns and cities. There are indeed a number compact small-growing varieties in commerce that at first sight are eminently suitable for such gardens, but in practice these plants may form only a minor element of the inventory carried by the average garden centre and many outlets do not stock them. In my experience the compact growing types can often have very small flowers, be difficult plants to keep alive and it is important at the outset to know which cultivars are both hardy and robust for the area in which the gardener lives. Many of the larger growing varieties of azalea, when planted in a semi-shaded position in a temperate garden with reasonable soil and average moisture availability can eventually reach six to seven feet in height and diameter. Prevention is better than the cure in respect of this type of problem.
So, who is to blame? A lack of communication is the answer. The plant label did not provide adequate advice on size at ten years of age or, at the time of purchase, the gardener failed to establish the ultimate size of the plant. Often the size given at ten years is somewhat subjective and provides little indication of the ultimate size the plant will grow to in twenty five years. Most garden centre staff are mainly financial turn-over oriented and, even if they know the answer to the query, they do not offer advice unless specifically requested to do so. Incidentally, plants should be compact and well-branched at the time of purchase and should not need to be pruned. If you find yourself considering pruning a plant that you are contemplating buying, then you should be shopping at some other garden centre!
It probably goes without saying that most acquisitions of evergreen azaleas, be they from friends or a garden centres, are driven by the flower colour or the way in which a particular cultivar tends to cover itself with flowers. A more basic consideration is often forgotten when acquiring plants, that is, to establish the geographic location the plant was bred for. Many of the evergreen cultivars currently found in the local garden centres were bred in three relatively small areas of the U.S.A.’s East Coast. The Glenn Dale hybrids were developed for the metropolitan area of Washington D.C. and the Beltsville hybrids were developed for the close-by State of Maryland. The Hershey, Gable, Robin Hill and Linwood hybrids were developed for Pennsylvania and New Jersey, whereas the North Tisbury and Saunder hybrids were developed for Massachusetts. These areas experience cold winters and shorter hours of daylight than Great Britain and it should be no surprise that these plants tend to become “leggy” if grown in a shady position in our temperate climate. This problem can be exacerbated by over-fertilisation or if the ground is too wet in mid to late-Summer. A more compact growth pattern can be achieved by locating these plants where they get sun for at least part of the day.
As much as we would like to, none of us can turn back the clock, so its time to deal with an azalea which has outgrown its location. Patience is the key to achieving a satisfactory end-product. So, before commence pruning, take time out to stand back and look at each of the plants you intend to work on remembering that, with azaleas, the branches that happen to have been shaded-out often die back and may be dead wood anyway. Remove these first as their removal will probably affect the way you will approach pruning the rest of the branches in order to maintain the shape of the bush, however, a word of caution before you start.
If you have recently removed some plants or trees that have previously shaded-out the azalea that you are about to prune, or are about to do so; or if the azalea itself has been recently transplanted in to a less shaded position, then it is suggested that you take a second look at the plant before you start pruning. If the general “stance” of the plant looks somewhat straggly and one of the aims is to achieve a more bushy plant, then it is important to retain a significant amount of leaf material on at least some of the remaining branches so as to promote new growth as quickly as practicable. This aspect is particularly relevant to rejuvenating plants that have been crowded together or are “one-sided” due to having grown against a wall or fence. A light feed with a high-potash fertiliser and also wetting the branches in a dry spell for the initial foot above the ground, tends to lead to good results in terms of buds breaking on bare branches near the base.
When pruning evergreen azaleas to reduce height or width it is important not to succumb to the temptation of attempting a drastic pruning of all the branches at the same time. Make certain that you avoid ending up with a plant that is completely bereft of foliage as some plants do not regenerate in this condition.