× Cuprocyparis leylandii Seeds | Leyland Cypress
LATIN NAME: × cuprocyparis leylandii
COMMON NAME: Leyland Cypress
Plant Profile
The plant is an intergeneric hybrid between Nootka cypress, a conifer of north-western North America, and Monterey cypress from the California coast. The cross arose at Leighton Hall, where the two parents stood close together, and the young plants were raised by the Naylor family, whose name the tree still carries. Only a handful of original seedlings were kept, and every hedge in the world descends from those few.
The foliage sits in flattened sprays of small scale leaves, dark green in most clones and grey-green or gold in others, and crushed in the hand it gives the familiar cypress smell. Rounded cones follow on older trees, but most of the seed inside them is empty, because the hybrid carries a chromosome complement well above that of either parent and its pollen is largely abortive. Where cones do fill, the offspring are variable and useless to a nursery.
The root plate is broad but shallow, which is the second reason the tree needs room. On wet or compacted ground a tall Leyland can be levered out by a winter gale, and repeated shearing keeps the hedge dense at the surface while the roots stay near the top. It dislikes ground that stays waterlogged through the winter.
Never cut back into bare, leafless wood, because the tree will not break again from an old limb. Keep the hedge within reach by trimming from the first season rather than letting it run. It is prone to Seiridium canker, which shows as sunken dead patches with resin bleeding, and to Phytophthora root rot on wet ground; remove affected branches promptly.
Science & Biotechnology
The leaf oil is the ordinary cypress monoterpene mixture, with alpha-pinene, sabinene and limonene at the head and smaller amounts of terpinen-4-ol and the sesquiterpene caryophyllene behind them. There is no valuable essential oil here. The chemistry matters as a taxonomic signature and because those same volatiles make hedge clippings pleasant to handle and serviceable as a rough mulch. Tissue-culture routes through axillary shoots have been tried, but rooted cuttings stay cheaper.
Uses & Benefits
Almost every Leyland cypress in the ground is a hedge, a screen or a windbreak. It takes coastal salt, tolerates heavy clay and grows quickly enough to block a view within a few seasons, which is exactly why neighbours object to it. Trim twice in a season to keep the face dense, and keep the top narrower than the base so light still reaches the lower branches; the gold clones are better kept as specimens.
Older hedges fail from the inside. When a row is trimmed only on the face, the shaded inner wood loses its foliage and dies, and a hedge cut back hard into that bare zone never fills again. The remedy is to keep trimming little and often from the start, and to replace a failing row outright, because a Leyland will not shoot from old brown wood.
Growing from Seed
Named selections such as ‘Leighton Green’, ‘Haggerston Grey’, ‘Castlewellan’ and ‘Naylor’s Blue’ differ in colour and hardiness, and gold forms like ‘Gold Rider’ and ‘Robinson’s Gold’ appeared later as bud sports. Because the plant does not come true, none of these can be raised from seed: the trade multiplies them as rooted cuttings, and a new sport is propagated only when someone finds it.
If you do raise plants from a filled cone, treat the seed like any hardy conifer. Sow on the surface of a mix of two parts compost, one part coarse sand and one part perlite, press each seed in no deeper than its own thickness, and keep the tray cool and moist, with good light. Leave enough space between the sowings that the seedlings do not shade one another, and pot them on before the roots coil.
The reliable route is a heel cutting taken in late summer from a shoot of the current season, pulled away with a sliver of older wood attached. Insert it in a gritty mix, keep it humid but never wet, and leave it through the winter before potting on. Plant out on the final spacing, because a mature Leyland reaches hedge dimensions fast and needs room if you want a closed face without constant clipping.
Our Take
If you want the Leyland look without the trimming ladder, look at the slower conifers in the same family. Italian cypress gives a narrow column without the width, Lawson cypress makes a softer hedge that copes with wind, and western red cedar is the better choice on damp ground.
Related Reading
More species in the same orbit as Leyland Cypress: