The ‘X’ preceding its Latin name ‘X Cupressocyparis leylanii‘ designates Leyland cypress as a hybrid of two distinct genera, namely Monterey cypress and Nootka cypress. (Those who consider the parents to be two species of the same genus know Leyland cypress as Cupressus X leylandii.) The many cultivars combine desirable qualities of both parents, but also innate weaknesses.
Rows of Leyland cypress grow fast to become densely evergreen windbreaks or informal screens within only a few years. However, they are very susceptible to cypress canker, and are likely to succumb within twenty five years or so. Farther inland, they may not last half as long. That may be quite acceptable for temporary windbreaks in front of slower but more permanent shrubby trees.
Common Leyland cypress develops a distinctly plump but conical form, with slightly grayish foliage. Most other cultivars are more columnar. Foliar color ranges from bluish green to gold. The tiny scale leaves are densely set in flat sprays. Healthy trees can get nearly thirty feet tall in ten years. Most stay lower where exposed. Crowded trees that live long enough exceed a hundred feet tall.
If good fences make good neighbors, what about hedges? If only it were that simple. There are all sorts of evergreen hedges to provide privacy, obstruct unwanted views, disperse wind, define spaces, or muffle noise. They can do much of what fences do, and muffle sound better. The problem is that they are composed of living plants, shorn into submission and very unnatural shapes.
Unlike fences, hedges need to be shorn very regularly. Otherwise, the shrubbery that they are composed of tries to grow into its natural forms. Slow growing plants like Japanese boxwood may only need to be shorn twice annually, especially if no one minds if it looks somewhat shaggy. Old fashioned glossy privet is so vigorous that it likely needs to be shorn a few times before autumn.
Even if the work of shearing is not a problem, accessibility might be. Hedges are popularly planted between properties. The outsides of such hedges are therefore accessible only from adjacent properties, which might have other plants or landscape features in the way. There is also the risk that the neighbors might not want anyone coming over to shear such a hedge! Beware of the dog!
Hedges in conjunction with backyard fences are easier to maintain as long as they are kept below or at the same height as their fences. They only need shearing on the inside and on top. Fences might be needed to keep dogs in or out anyway. When planning for a new hedge, other plants and garden features that might obstruct access within the same landscape must be considered too.
Taller hedges should be shorn so that they are slightly narrower on top, and wider at the bottom. This promotes more uniform growth, and hopefully prevents basal baldness. Upper growth gets more sunlight than lower growth, so grows faster, and too often shades out lower growth while becoming distended up high. Hedges should also be watered and fertilized evenly from end to end.
It is important to remember that hedges work for the landscape, and should not be allowed to dominate. Fat hedges waste space. A well groomed hedge that is only two feet from front to back works just as well as a hedge that is three times as plump. Feral plants that ‘volunteer’ within a hedge must be removed instead of shorn along with the hedge. They only compromise uniformity.