The Leyland Cypress

— Written By

When a plant doesn’t necessarily need much care to become established, has a fast growth rate, and is adapted to a variety of growing conditions you would probably want that particular plant somewhere within your home landscape, correct? Well, the plant I’m referring to is Leyland cypress and it has been on the garden scene for several decades now. Leyland cypress is a hybrid of two plants from the Pacific Coast, Monterey cypress (Cupressus macropcarpa) and Alaska cedar (Chamaecyparis nootkatensis). The offspring of that cross produced what we know as the Leyland cypress or x Cupressocyparis leylandii. As you can see, the Latin scientific names of plants can be quite the mouthful!

Leyland cypress gained popularity as an excellent plant for screening purposes. It is an evergreen and has a pyramidal growth pattern that is flared at the base and slowly tapers as the tree gains in height. It does well at denoting property boundaries, as a shield to wind, and for general privacy purposes. It grows rapidly outpacing many plants in the landscape at 3 to 4 feet per year when young. The tree matures at 60 to 70 feet tall and 14 to 18 feet wide. This can be deceiving while purchasing the plant when it is cute, small and somewhat resembles a Charlie Brown Christmas tree. The Leyland cypress is certainly not a plant to be installed near the foundation of your home or in immediate proximity to one another. They need room to grow!

Leyland cypress is an excellent plant in certain situations. There are diseases and certain pests of Leyland cypress. One of the most common reasons for Leyland cypress decline is due to being improperly planted. This stress can lead to increased disease and insect pressure. Leyland cypress should be planted a minimum of 10 to 15 feet apart. Yes, you read that correctly. Unfortunately, many of these plants are planted mere inches apart from one another creating instant crowding issues within the first couple of years post-planting. These are large trees when mature and one must understand a specific plants growth habit before planting. Always remember, right plant, right place. Also, be careful not to over plant these trees, or any plant for that matter when trying to create a hedge or screen. Always strive to mix your selection of plants to diminish the effects potential pests and diseases may bring. You can intermix your hedgerow with similar plants in appearance and growth pattern of Leyland cypress. One of these is Arizona cypress (Cupressus arizonica) for dry sites in full sun. Another is ‘Green Giant’ arborvitae (Thuja plicata ‘Green Giant’) for moist and well-drained sites in full sun. Japanese cedar (Cryptomeria japonica) develops a tall, columnar screen in partly shady areas. There are also many hollies to choose from such as ‘Nellie R. Stevens’ and Lusterleaf holly (Ilex latifolia). Using hollies also provides unique color interest with the red berries they provide.

One destructive pest of Leyland cypress are bagworms. These pests create nesting structures from weaving the leaves of the tree into cylindrical bags. Symptoms usually won’t appear until you have a substantial infestation. An effective control measure is to remove the bags during the winter and immediately destroy them. An organic method you can apply is Dipel which is a natural bacterium available at your local garden center. This is more effective when the worms are small and can be applied in May. Control of bagworms later in the year is possible with contact insecticides. If you notice your tree defoliating, entire branches dying, or exudation of sap from the trunk and branches then you may have a more serious problem. These symptoms are synonymous with several canker diseases of Leyland cypress. Unfortunately, there is no chemical control for these diseases. However, if you’re trying to salvage the tree it is recommended to prune out diseased portions where possible. This could extend the life of the tree, but research is inconclusive. Also, many evergreens undergo “needle drop” where they will begin to shed some of their interior foliage. As long as you don’t notice any other potential signs of stress then this is no cause for concern. Also, remember to provide water and fertilization to newly planted trees and shrubs in the landscape. While autumn is the ideal time for the installation of trees and shrubs, proper and consistent watering during the summer months will increase the chances of your plants survival.

Colby Griffin is the horticulture agent for NC Cooperative Extension in Edgecombe County. If you have any questions about this article or other gardening issues, he can be reached at colby_griffin@ncsu.edu or 252-641-7815.