Leyland cypress

Sun

Full sun is best; tolerates light shade but grows less densely.

Water

Water regularly while establishing, then during prolonged drought. Established trees tolerate some dryness, but drought stress increases the risk of canker.

Soil

Adaptable to acidic, neutral or alkaline soils, provided drainage is good. Avoid waterlogged ground and very shallow, drought-prone soil.

Height

60-80 ft (18-24 m) unpruned; old trees can grow taller.

Spread

15-25 ft (4.6-7.6 m) unpruned.

Foliage

Evergreen. Dense sprays of scale-like, usually dark green leaves; some cultivars have yellow or blue-green foliage.

Growth

Fast; commonly 2-3 ft (0.6-0.9 m) a year when young and well established.

Care needed

High

• Plant with the root flare at ground level in well-drained soil; allow for mature width and keep clear of buildings, overhead wires and neighbouring boundaries.
• Water deeply through the first two growing seasons, checking soil moisture rather than watering on a fixed schedule.
• Spread 2-3 in (5-8 cm) of organic mulch over the root zone, keeping it away from the trunk.
• Feed only if growth is weak and soil fertility is poor; avoid heavy nitrogen feeding.
• Stake only if the root ball moves in wind, and remove supports once roots anchor the tree, usually after the first growing season.
• Keep soil around young trees free of competing grass and weeds.

Pruning. Trim hedges two or three times from late spring through summer, keeping the base wider than the top and checking for active bird nests first. Cut only into green, leafy growth: bare old wood usually will not regrow, and reducing an overgrown hedge severely often leaves permanent brown areas.

Spring

Plant in colder regions once the soil is workable; water thoroughly and mulch.

Late spring

Make the first hedge trim after checking for nesting birds; retain green foliage on every cut branch.

Summer

Check young plants weekly during dry weather and water deeply when the root zone starts to dry.

Midsummer

Trim vigorous hedge growth again, keeping the sides slightly tapered.

Late summer

Inspect for browning, cankers, mites and bagworms; avoid late trimming where frost arrives early.

Autumn

Plant in mild regions while soil is warm, and water established trees if autumn is unusually dry.

Winter

Check stakes and storm damage; arrange professional assessment of split or unstable large trees.

• A tall evergreen boundary screen on large plots, where regular trimming and access on both sides are practical.
• A windbreak for exposed rural gardens, planted well away from buildings and smaller plants.
• A clipped green backdrop to broad mixed borders, with flowering plants positioned beyond the driest root zone.
• An untrimmed evergreen specimen or group in spacious grounds, where its narrow pyramidal outline can develop naturally.

Garden styles it suits: Formal, Traditional, Grand estate, English country, Green on green and Winter interest.

Plant it with: Epimedium, Hellebores, Bergenia, Mahonia and Hardy geraniums.

Wildlife: Dense foliage provides shelter and nesting sites for birds, but the tree offers relatively little nectar or food compared with a mixed hedge of locally native shrubs. Check carefully for occupied nests before trimming.

• Cypress canker causes scattered brown branches, sometimes with resinous lesions. Reduce drought stress, prune affected branches back to healthy wood in dry weather and clean tools between cuts; replace severely affected trees.
• Phytophthora root rot causes decline in wet ground. Correct drainage before planting and remove badly affected trees; watering or feeding will not repair rotten roots.
• Bagworms, especially in parts of the United States, strip foliage. Remove bags by hand before eggs hatch; where infestations are extensive, treat young larvae with a locally approved control.
• Oversized hedges and bare brown sides result from delayed pruning or cutting into old wood. Maintain the intended outline from a young age; replace plants where a major size reduction would leave bare branches.

Foliage is considered harmful if eaten by people, and sap or foliage contact can cause skin irritation or allergic reactions. Species-specific poisoning information for cats, dogs and horses is limited; serious toxicity is not well established, but keep foliage and hedge clippings out of their reach and never use clippings as feed.

• Lawson's cypress (Chamaecyparis lawsoniana)

  Usually has flatter sprays with clearer pale markings beneath, often a drooping leading shoot, and smaller round cones than Leyland cypress.

• Western red cedar (Thuja plicata)

  Has broad, flattened fans with conspicuous pale markings beneath and small elongated cones, rather than the round woody cones of Leyland cypress.

• Monterey cypress (Cupressus macrocarpa)

  Often develops a broader, more irregular crown and bears larger woody cones; crushed foliage commonly has a strong lemon-like scent.

The name leylandii honours Christopher John Leyland, who cultivated early examples of this hybrid between Monterey cypress and Nootka cypress.

Propagation. Usually propagated from semi-ripe cuttings in late summer, using a free-draining medium and humid conditions. Rooting can be slow and uneven; seed is scarce and does not reliably reproduce named cultivars.

Accepted botanical name

Cupressus leylandii

Sources: GBIF (CC BY 4.0). The care and design notes are LandscapeGPT's own.