How to ID and Manage Leyland Cypress

A rapidly-growing evergreen when young, Leyland Cypress will easily grow three to four feet per year, even on poor soils, and can ultimately attain a height of some 50 feet. The tree forms a dense, oval or pyramidal outline when left unpruned, but the graceful, slightly pendulous branches will tolerate severe trimming to create a formal hedge, screen or windbreak. The tree quickly outgrows its space in small landscapes and is too big for most residential landscapes unless regularly trimmed. Unusually, shallow roots of the species can give in wet soil to topple large trees.

Scientific name: x Cupressocyparis leylandii
Pronunciation: x koo-press-so-SIP-air-iss lay-LAN-dee-eye
Common name: Leyland Cypress
Family: Cupressaceae
USDA hardiness zones: 6 through 10A
Origin: not native to North America
Uses: hedge; recommended for buffer strips around parking lots or for median strip plantings in the highway; screen; specimen; Christmas tree
Availability: generally available in many areas within its hardiness range

Height: 35 to 50 feet
Spread: 15 to 25 feet
Crown uniformity: symmetrical canopy with a regular (or smooth) outline, and individuals have more or less identical crown forms
Crown shape: columnar; oval; pyramidal
Crown density: dense
Growth rate: fast
Texture: fine

Leaf arrangement: opposite/subopposite
Leaf type: simple
Leaf margin: entire
Leaf shape: scale-like
Leaf venation: none, or difficult to see
Leaf type and persistence: evergreen
Leaf blade length: less than 2 inches
Leaf color: blue or blue-green; green
Fall color: no fall color change
Fall characteristic: not showy

Trunk/bark/branches: grow mostly upright and will not droop; not particularly showy; should be grown with a single leader; no thorns
Pruning requirement: needs little pruning to develop a strong structure
Breakage: resistant
Current year twig color: green

Light requirement: tree grows in part shade/part sun; tree grows in full sun
Soil tolerances: clay; loam; sand; acidic; alkaline; well-drained
Drought tolerance: high
Aerosol salt tolerance: moderate
Soil salt tolerance: moderate

This tree is a fast grower and, if not pruned early, can get out of hand as a hedge. In the first year trim back long sideshoots at the start of the growing season. Trim sides lightly in late July. The sides can be trimmed the following to year encourage denser growth. Continue to trim the sides each year leaving the leading shoot untouched until the desired height is reached. Topping and regular trimming of the sides should prevent trees from becoming increasingly large.

Seiridium canker disease, also called coryneum canker is a slow-spreading fungal disease of Leyland cypress. It disfigures and damages trees, particularly in hedges and screens that are heavily pruned.
Seiridium canker is usually localized on individual limbs. The limb is usually dry, dead, often discolored, with a sunken or cracked area surrounded by living tissue. You should always destroy diseased plant parts and try to avoid physical damage to plants.
Sanitize pruning tools between each cut by dipping in rubbing alcohol or in a solution of chlorine bleach and water. Chemical control has proven to be difficult.

Dr. Mike Dirr says about Leyland Cypress: "...it should be restrained at an early age before pruning becomes impossible."

Leyland Cypress grows in full sun on a wide range of soils, from acid to alkaline, but looks its best on moderately fertile soil with sufficient moisture. It is surprisingly tolerant of severe pruning, recovering nicely from even severe topping (although this is not recommended), even when half the top is removed. It grows well in clay soil and tolerates poor drainage for a short period of time. It also is very tolerant of salt spray.

Some available cultivars include: ‘Castlewellan’, a more compact form with gold-tipped leaves, excellent for hedges in cool climates; ‘Leighton Green’, dense branching with dark green foliage, columnar form; ‘Haggerston Gray’, loose branches, columnarpyramidal, upturned at ends, sage-green color; ‘Naylor’s Blue’, blue-grey foliage, columnar form; ‘Silver Dust’, wide-spreading form with blue-green foliage marked with white variegations. Propagation is by cuttings from side growths.