Remarkably well-growing in any fertile, well-draining soil type, Leyland cypress trees became popular tall formal hedgerow choices where fast-growing plants were desired. Best grown in U.S. Department of Agriculture hardiness zones 6 through 10, it tends to keep tighter branching where summers are not particularly hot. Many varieties of this evergreen tree exist, with varying foliage colors ranging from emerald green to yellow to blue-green.
The Leyland cypress is a man-made hybrid created in 1888 on the Leighton Hall estate near Welshpool, Wales, in Great Britain. The parent trees are Monterey cypress (Cupressus macrocarpa) native to California and the Nootka false cypress (Chamaecyparis nootkatensis) native to from Oregon to Alaska.
Normally plant hybrids are possible only between species within a single genus, a very closely related and similar grouping of plants. The Leyland cypress carries notable merit because it is a viable cross between species of two different genera (Cupressus and Chamaecyparis), called an intergeneric hybrid. While the original 1888 hybridization used the pollen of the Monterey cypress upon female cones on the Nootka false cypress, reversing the cross also yields trees with varying physical characteristics, like foliage color or mature size.
Extremely fast-growing, increasing branch length or height by upwards of 3 to 4 feet each year, Leyland cypress can reach an old maturity of 100 to 130 feet in height. Usually in cultivation it attains a 40- to 55-foot size. It remains a narrowly shaped tree, perhaps 10 to 15 feet in width at most. The foliage is scaled and wispy, more closely resembling the foliage of the Nootka false cypress, according to the Floridata website. It remains evergreen and acts as a dense screen, hedgerow or windbreak.
Leyland cypress grows its fastest and most luxuriously in fertile, moist soils that drain well. Once its root system is established, it tolerates droughts well and is resilient to breezy seaside conditions. The tree grows in heavy clay soils, too, but it is short-lived in any soil that is soggy or repeatedly floods after rains. Grow it in sunny locations where it gets no less than six hours of direct sun daily. Insufficient light causes irregularly shaped trees or sparse foliage.
Bagworm infestations can defoliate trees within two weeks, according to the U.S. Forest Service, and can be a serious problem. After periods of drought, canker can inflict Leyland cypress, quickly browning foliage and killing trees. In overly wet periods of prolonged high humidity, occasional problems with foliage fungus may arise, too. In the American Southeast and California, this tree's fast growth and inexpensive cost found it abundantly planted in the later 20th century. Canker fungi in particular kills trees incorporated into dense hedges, leaving gaping holes. Alternatives to Leyland cypress include arborvitae (Thuja spp.), Arizona cypress (Cupressus arizonica) and Japanese cedar (Cryptomeria japonica).