Leyland cypress is one of the most popular plants used in the landscape as a natural screen. Unfortunately, increasing disease problems, improper plant placement, and the continuous mass plantings of Leyland cypresses have all contributed to the need for alternative plant selection.
Leyland cypress trees are susceptible to a number of diseases, such as Seridium canker, Botryosphaeria canker, Cercosporidium needle blight, and Phytophthora root rot. Planting the trees too close together and planting them in unfavorable sites greatly increases the incidence and spread of disease. Certain insect infestations, such as bagworm and spider mites, have also become more and more common recently. Other problems seen in Leyland cypress occur because they are often seen as the one and only solution to all screening needs in the landscape.
They require full sun to grow well, so those placed in shady areas often look thin and weak. Many people don’t realize that Leyland cypresses can grow 60 to 70 feet tall, which can lead to the trees having to be drastically topped when planted under utility lines. They also don’t like “wet feet,” so placing them in poorly drained soils increases root rot disease.
In looking for an alternative natural screen, it is best to consider using several different trees as a substitute. Planting a variety of species in groups of 3’s, 5’s, or 7’s to ensure that it is aesthetically pleasing to the eye. Choosing well-adapted plant material for our environmental conditions will result in healthier plants and reduce disease and insect infestations.
If you are looking for a tall, narrow conifer similar to Leyland cypress, consider an Arizona cypress for dry sites in full sun. Green Giant arborvitae will work well in moist, well-drained sites in full sun. Japanese cedar, also known as Cryptomeria, makes a good tall screen in partly shaded areas.
Also consider broadleaved evergreens for dense screens that also have flowers or berries for seasonal color. Hollies make a good screen plant, and most can tolerate either sun or partial shade. Foster’s holly is tall and narrow and would be good where width is an issue. In less restricted spaces, lusterleaf holly and Nellie R. Stevens holly can be used. Other broadleaf evergreens that can be used for a screen of up to 25 feet tall are fragrant tea olive, Fortune’s tea olive and loquat. In many cases, smaller screens of 6- to 15-feet tall are sufficient. For these, consider choices like wax myrtle, taller varieties of Japanese hollies such as convexa or steed’s, viburnums, cleyera, and loropetalums. If you are looking for just a barrier to impede traffic, more so than a screen, try installing Chinese hollies or a barberry species. My personal favorite is Berberis julianae - Wintergreen barberry; it’s drought tolerant, one of the hardiest evergreen barberries, can be severely pruned, and its two to three inch spines in groups of threes will stop anything in its tracks.
It is important to remember to diversify your screening plants. Having many different plants helps stop the spread of problems from one plant to the next. Even if one or two plants in the screen have a problem, removing them will not require removal of the entire screen. If possible, try staggering rows of plant material. This allows the plants to be spaced more widely, allowing for better air circulation, which will reduce disease and insect infestations.