Originating in the 1880s in England when the Monterey cypress (Cupressus macrocarpa) and Alaskan cedar (Chamaecyparis nootkatensis) where hybridized, the Leyland cypress (x Cupressocyparis leylandii) today is valued by gardeners as a fast-growing tree. Potentially growing 30 to 80 feet tall and 10 to 20 feet wide, it is widely used in the United States to create tall and large evergreen hedges. Grow Leyland cypress in a sunny location in a moist, well-draining soil in U.S. Department of Agriculture Hardiness Zones 6 through 9.
The variety "Castlewellan" stands out from other varieties of Leyland cypress with its plume-like sprays of yellow-green scaled needles. Also called "Galway Gold" or "Castlewellan Gold" in the horticultural trade, the new foliage in spring is an intense golden yellow color and will mellow out slightly in summertime. In chilly winter months the feathery foliage attains hints of bronze coloration and can mask the yellowish needles. "Castlewellan" grows tall and narrow: 60 to 80 feet in height and 8 to 12 feet wide.
Unlike other Leyland cypress trees that typically grow around 2 to 3 feet a year, "Gold Rider" grows only about 12 inches per year, eventually maturing to 35 feet tall and no more than 15 feet in width. This gold-needled selection was found growing in Holland in the 1980s. The new tip growth is bright yellow while the shaded interior foliage is lime green in color. A lack of direct sunlight will diminish the intensity of the yellowish gold coloration of the foliage.
"Naylor's Blue" is a variety of Leyland cypress known for its attractive blue-gray foliage. It matures 60 feet tall and 10 to 15 feet wide. The color of the scaled needles varies, which is a key ornamental feature. After a summer rain the bluish hues in the foliage are heightened, creating a contrast with the red-brown twigs. In winter, the cold temperatures tend to dull the blue and make the needles look much more ghostly gray.
While plant literature often describe the needles of "Haggerston Grey" to be gray-green, visually it looks medium kelly green in the growing season. Only in fall, winter and early spring are the more grayish tints obvious over the green. It grows 60 to 80 feet tall and 10 to 15 feet wide with a much more open-branching, loose pyramid shape.
A mutant sport that was propagated off of a Haggerston Grey plant, "Harlequin" (also incorrectly labeled as "Variegata") has gray-green foliage with random patches of ivory-cream colored needles. The visual effect makes the tree look pastel in color--a combination of ivory and gray-green that does not have a heavy presence like an evergreen with dark green leaves. The tip of this tree tends to have several leader branches, the upright leading tips that define the height of the plant. "Harlequin" grows 35 to 45 feet tall and 8 to 12 feet wide.