Over the last decade or so Leyland cypress became extremely popular as screening plants. They provided homeowners with a very rapidly growing screen and served to fill the gap in the choice of screening plants left when red-tip photinias began to suffer from severe leaf spot disease problems.
Unfortunately, the same circumstances that led to the loss of viability of red-tips as landscape plantings are now affecting the use of Leyland cypress for screening. When a plant becomes so popular that it is planted everywhere, formerly minor pest problems can develop into major problems.
Leyland Cypress Problems
Problems with established trees began cropping up several years ago, and the incidence of damage from disease and insect pests has increased every year. Seiridium canker, Botryosphaeria dieback and Cercosporidium needle blight are becoming increasingly common in landscapes as are infestations of bagworms and spider mites. Because of the height of the plants, treatment is difficult or impossible for most homeowners.
Other problems occur simply because Leyland cypress are often seen as the one solution for all screening needs and are planted in situations inappropriate for them. Planting in poorly drained or wet soils, or where excessive overwatering occurs often leads to fungal root rots. Leyland cypress requires full sun to grow well, and when planted in shade, rapidly thins and sheds lower branches. Failure to realize how very tall the plants become (60 to 70 feet tall) leads to trees being planted in improper places, such as under overhead utility lines where a shorter screen would be quite adequate. The desire for instant screening often leads to trees being planted too closely, which results in overcrowding at maturity. Overcrowding leads to problems with poor air circulation, increasing the possibility of disease occurrence and shading out of lower branches.
Selecting Screening Plants
Because of all these problems, it is necessary to consider substitutes (not just a single substitute) for Leyland cypress in the landscape. The idea is to choose plants for a particular site based upon cultural conditions and aesthetic considerations. It is best to have diversity in the landscape. The use of a variety of well-adapted species, whose requirements match the site conditions, results in more healthy plants.
When choosing screening substitutes for Leyland cypress, consider the actual needs – both of site conditions, and of screening purpose. How high does the screen really need to be for privacy? Few home sites actually require the height that Leyland cypress can ultimately reach. What is the purpose of the screen? Is full year privacy needed, or is screening needed only in certain seasons and for parts of the property? If instant privacy is needed, a fence fronted by shrubs and trees for interest may be more suitable than overcrowding plants. Alternatively, two staggered rows will create a screen more quickly with less chance of crowding. Also consider the contribution to the overall landscape that screening plants will provide. The best screening solutions should be a part of the total design for the property.
Recommended Screening Plants
For those who desire a tall narrow conifer similar in form to Leyland cypress, consider Arizona cypress (Cupressus arizonica) for dry sites in full sun or ‘Green Giant’ arborvitae (Thuja plicata ‘Green Giant’) for moist, but well drained, fertile sites in full sun. Japanese cedar (Cryptomeria japonica) makes a fine tall screen in partly shady areas.
Many broadleaved evergreens make excellent dense screens and also provide flowers or berries for seasonal interest. Tall, narrower cultivars of Southern magnolia (Magnolia grandiflora) such as ‘Alta’, ‘Bracken’s Brown Beauty’ and ‘Edith Bogue’ are ideal for screening. In areas where not quite as high or wide a screen is needed, ‘Little Gem’ is very compact and upright in growth. Sweetbay magnolias (M. virginiana) will tolerate moister soil than most. The cultivars ‘Henry Hicks’ and ‘Santa Rosa’ are reliably evergreen.
Hollies provide a multitude of choices for tall screening plants. ‘Foster’s’ holly, the closely related ‘Savannah’ holly (both Ilex x attenuata), and the Aquipernyi hollies (I. x aquipernyi) ‘Dragon Lady’ and ‘Carolina Sentinal’ are all tall, narrow hollies suitable for areas where plant width is a consideration. In less restricted areas, broader hollies such as lusterleaf holly (Ilex latifolia), ‘Nellie R. Stevens’ holly, and many others can be considered. Most hollies grow well in either sun or part shade.
Other broadleaf evergreens to consider for relatively tall screening include fragrant tea olive (Osmanthus fragrans), Fortune’s tea olive (O. x fortunei) and loquat (Eriobotrya japonica) which will all grow to about 25 feet tall.
In many cases screens that range between 6 and 15 feet tall will be sufficient to provide privacy. For these areas, numerous choices are available. Wax myrtle (Myrica cerifera) is excellent for many difficult sites with it’s tolerance of sand, wind, salt, and poor soil. It does require full sun. Taller varieties of yaupon holly (Ilex vomitoria) will give a fine texture and will tolerate a variety of difficult growing conditions from wet to dry soil, and even salt spray in sun or light shade. There are viburnums available for virtually any situation, and they will add to the landscape with flowers and berries. Cleyera (Ternstroemia gymnanthera), plum yew (Podocarpus macrophyllus), tall forms of loropetalums, camellias, shorter tea olives and many other species should be considered when looking for appropriate screening for a site.
It is important, though, not to search for only one plant as the Leyland cypress substitute. Overuse of any single plant species or cultivar would likely lead to a repeat of the monoculture problems that struck red-tip photinia and is now striking Leyland cypress. A better solution for screening is to create a mixed screen, where multiple species are grouped together in small clusters of three or five, either in a single row where space is tight, or in an alternate layered planting where possible. Mixed-species screens help prevent the spread of problems from one plant to the next. An advantage of several rows of staggered plants is that they can be spaced more widely , allowing for better air circulation, while still achieving a full screen. Good air circulation helps reduce the incidence of disease problems.
In a mixed screen, even if one species does develop problems that are so severe it has to be removed and replaced, the entire planting will not be sacrificed. Mixed screens can also be far more interesting and rewarding throughout the seasons, offering the chance to turn a utilitarian screen into a beautiful part of the entire landscape.
Originally published 03/07