Leyland Cypress

Light and exposure

Leyland cypress grows equally well in full sun or partial shade, without much fuss either way. It copes very well with wind, which makes it an excellent windbreak for exposed gardens, on open plateaux as much as near the coast.

A spot that is too shady at the back of the garden slows its growth and gives thinner foliage on the shaded side. For an even hedge over its whole height, give it a spot that gets sun for a good part of the day.

Watering

At planting and for the first two seasons, water regularly to help the roots establish, especially in sandy soil or during a dry summer. A Leyland cypress that fails to root well in its first year stays stunted for a long time and never really catches up with the rest of the hedge.

Once established, it becomes remarkably drought tolerant. Its root system, though, is powerful and hungry: it dries out the soil for several metres around the hedge, which is often bad news for beds or plantings put in right next to it.

Soil and repotting

Leyland cypress adapts to almost any soil, including the chalky, poor soils found in parts of the region. Ordinary, even middling soil is more than enough for it to thrive.

Its real weak point is waterlogging. In heavy, poorly drained soil the roots suffer and the door opens to Phytophthora dieback. On ground that holds water in winter, it is better to plan for drainage or a planting mound than to put it straight into soaked soil.

Temperature and humidity

Leyland cypress is perfectly hardy down to about minus twenty degrees, USDA zone 6 and above: in a temperate climate it comes through winter without any damage. Cold is never its problem.

What it minds more is drying wind combined with frost on young plants in their first year, which can brown foliage exposed to cold draughts. Once the hedge is established and has thickened up, this risk almost disappears.

Pruning and upkeep

This is the point that makes all the difference between a fine hedge and a dispute with the neighbours. Leyland cypress does not resprout from old wood, exactly like thuja: if you cut too hard into the brown part with no green needles left, that branch never turns green again and leaves a permanent gap in the hedge.

The rule is simple: trim early and often, two to three times over the growing season, cutting only into this year’s growth and always staying within the green. Never let the hedge get away from you thinking you will catch up later, that is the classic trap that leads straight to a wall several metres tall that can no longer be brought back into shape without disfiguring it.

Pests and diseases

Phytophthora dieback mainly affects plants in heavy, wet soil: the crown yellows then browns in patches, and sometimes a whole stretch of hedge declines over a couple of seasons without an obvious cause at first glance. Seiridium and Coryneum canker shows up as isolated branches browning and dying in the middle of an otherwise healthy hedge, often following a pruning wound or a bout of water stress.

In hot, dry summers, spider mites happily move in and leave the foliage dull, speckled and turning bronze. Watering at the base during heatwaves helps keep them at bay. None of these problems is inevitable, but they are reason enough to check on the hedge now and then rather than forgetting about it once it is planted.

Propagation

Leyland cypress is a sterile hybrid: it produces no viable seed and so never self-sows in the garden, unlike many other conifers. The only way to propagate it is from cuttings.

Take semi-ripe cuttings around ten centimetres long in late summer or autumn, from this year’s wood that has not yet fully hardened. Rooting hormone clearly improves the strike rate. It is slow going, expect several months before roots appear, which is why young plants in garden centres stay fairly pricey for such a common plant.

Month-by-month care calendar

Green Hub tips

• Never let the hedge get away from you thinking you will catch up later: trimming early and often, two to three times a season, is the only way to keep a Leyland cypress dense and manageable.
• Never cut into brown wood with no green needles left: unlike many shrubs, Leyland cypress does not resprout from old wood, and a branch cut back too hard never turns green again.
• Before planting a Leyland hedge on a property line, check the distance and height rules that apply where you live: it is the hedge that causes the most disputes between neighbours, between height they consider excessive, shade cast over the garden next door and roots that dry out their beds.
• If the idea of trimming several times every summer for the rest of your life does not appeal, go for yew or hornbeam instead: slower to establish, but far easier to live with in the long run.