Guest Article--Leyland Cypress--A Case of the Good and the Bad

Most homeowners in the southeast are familiar with the plant Leyland Cypress, if not by name, then certainly by sight. It has become one of the most popular needled evergreen trees in the nursery trade. Its formal name is x Cupressocyparis leylandii. It is a man-induced intergeneric hybrid between Cupressus macrocarpa (which is the Monterey Cypress found on the similarly named peninsula in California) and Chamaecyparis nootkatensis (which is the Alaska or Yellow-Cypress). The "x" before its scientific name signifies it is an intergeneric cross. Intergeneric hybrids, both plant or animal, are very rare in nature.

Why all the hype about Leyland Cypress? Why is it so popular? Its most desired feature is its fast growth rate. It can easily grow 3 feet a year and up to 100 feet high by 20 feet wide in 60 years, creating a barrier that quickly blocks such views as that of your neighbor's unsightly RV and other public displays of inappropriate behavior. Other features that make it desirable include:  its needled evergreen habit forming a pleasing (at least to some) columnar-to-pyramidal outline; fine, feathery, blue-green foliage contributing to the gracefulness of the species; tolerance of extreme environmental and soil conditions; generally good resistance to insect and disease pests; ease of propagation; and low cost. By golly, this sounds like the perfect plant! After all, millions have been planted in the last 20 years; you see them everywhere. In the grand scheme of things, however, probably none of these man-desired features will count a whit towards this plant's ultimate long-term natural survival.

This plant seems almost too good to be true. Unfortunately, in many instances, it is. In general, fast-growing plants tend to be short-lived and have structural problems as they mature. It is not uncommon for the above-ground portions of Leyland Cypresses to grow faster than their root systems, resulting in trees that uproot and fall over, especially during winter storms. This problem is exacerbated by container nursery growing practices that focus production on rapid shoot growth at the expense of healthy root growth, often leading to harmful girdling roots and pot-bound conditions. This tree, like many large-needled evergreens, tends to lose its bottom branches as it gets older, and this defeats the main purpose for which it is most often planted, which is to visually block an undesirable view less than 15 feet above the ground.

This scenario sounds eerily like that we experienced with the Bradford Pear over the last 40 years; we once thought it, too, was the perfect ornamental tree and proceeded to plant it everywhere, only to discover later that it has major structural problems as it matures. This just shows that there really is no such thing as the perfect plant, and we should be cautious of the problems that over-planting Leyland Cypress may bring in the future. Good planting design involves locating plants where they can reach their full genetic potential with minimal human interference. For Leyland Cypress, this means a sunny site that is big enough and far enough away from buildings and utilities to accommodate a plant that gets 100 feet by 20 feet in two generations.

Most people who buy and plant Leyland Cypress trees have no idea that they will grow to over 100ft. tall, or that keeping them lower than this, say as a 10 foot hedge, will be a significant maintenance challenge (financially and time-wise), or that they will only serve their intended purpose for maybe 20 years. If they knew these details, they probably would not plant them 3 feet from the house foundation or space them 3 feet apart right on the property line or driveway edge like you see in almost every neighborhood in the southeast.

This leads us to the fundamental question, "is there a problem with Leyland Cypress trees or with people who grow and plant them?" There is nothing wrong with the plant if it is allowed to achieve its full genetic potential in the proper environment. However, if it is put in the wrong place, then it will eventually (usually sooner than later) lead to problems and disappointment. This is a good example of an instance where the solutions we seek and employ are often shortsighted, based more on the desire for quick, cheap results than good, long-term satisfaction. It is also an example of how mass marketing can affect buying decisions. There are other plants better than Leyland Cypress for small, low-maintenance privacy hedges or specimen evergreen planting, and people who choose these other plants are usually much better off. How many Leyland Cypress trees do you have in your landscape? Where are they located? Do you think they might create some problems in the future?

Andrew J. White is President of Wayside Landscape Services, Inc. of Asheville, NC. His credentials are too many to list here! Fortunately, you can learn more about him at http://www.waysidelandscape.com
This article first appeared in WNC Builder/Architect. Give the page a moment to load.

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