Cupressocyparis leylandii Seeds | Leyland Cypress

Flat, brown Leyland Cypress seeds in opened cones, most of them empty and papery — Leyland Cypress (*Cupressocyparis leylandii*): Cupressaceae, a sterile hybrid first raised at Leighton Hall in Wales in 1888.

LATIN NAME: Cupressocyparis leylandii

COMMON NAME: Leyland Cypress

Plant Profile

Leyland Cypress is a fast-growing evergreen conifer with a dense, columnar habit, reaching twelve metres or more in thirty years. Its foliage is made up of flat sprays of soft, dark-green scale leaves, and its habit is intermediate between those of its two parents, which is exactly what it is: a hybrid.

It arose by chance in 1888 at Leighton Hall in Wales, where a Monterey cypress and a Nootka cypress grew close together, and every Leyland in cultivation descends from that single cross. It is a sterile hybrid, so it sets no viable seed and is propagated entirely from cuttings.

Science & Biotechnology

The plant is a bigeneric hybrid between Cupressus macrocarpa and Xanthocyparis nootkatensis, and its origin has been studied both by conventional crossing and by molecular means. Because it is sterile, the seed produced by a Leyland cypress is almost always empty, and any seedling that does appear is likely to be a hybrid with another cypress rather than a true Leyland.

Its vigour comes from hybridity: the cross combines the fast growth of Monterey cypress with the cold hardiness of Nootka cypress, and the result grows a metre or more a year in good conditions. The same vigour is why it needs constant clipping and why it has become a controversial hedge plant. The original clone, named Haggerston Grey, and the later Castlewellan Gold differ in foliage colour and hardiness, and both are still sold.

Uses & Benefits

Its main use is as a screen and a windbreak, where its dense evergreen habit and rapid growth are unmatched. It is also grown as a specimen conifer and, in some gardens, clipped into formal shapes.

The drawbacks are well known: it grows too fast for small gardens, it shades out everything beneath it, and it is prone to dieback from Phytophthora and from drought. Where space allows, it is an effective shelter tree; where it does not, a slower conifer or a mixed hedge is usually a better choice. Its dense foliage also makes it a favoured nesting site for small birds, though the shade beneath it keeps the ground bare.

Growing from Seed

Because the plant is sterile, seed is not a reliable route. Any seed collected from a Leyland is likely to be empty or to produce a different hybrid, so named plants are raised from cuttings taken in late summer and rooted in a cold frame.

If you do sow seed, treat it as an experiment: stratify it cold for six weeks, sow it in a free-draining mix at 15 to 20 °C, and expect low and unpredictable germination. Plant the resulting tree in full sun in deep, fertile soil, and allow far more room than seems necessary, since it will fill it within a decade. In a garden, plant it at least three metres from a boundary, because the roots and the shade both travel further than the crown suggests.

Our Take

A superb shelter tree and a poor garden neighbour, and one that comes true only from cuttings. Sow the seed for curiosity, not for a hedge.

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