When and How to Cut a Leylandii Hedge

By Paul Watmore, Director at Grasslands Nursery

Cut a Leylandii hedge two or three times between spring and early autumn to keep it dense and to size — and never cut back into the old brown wood, because Leylandii will not regrow from it. Trim while it is actively growing, keep the sides and top within the green growth, and stay on top of it: a neglected Leylandii is very hard to bring back. Here is how.

Why regular trimming matters

Leylandii (x Cuprocyparis leylandii) is the fastest-growing common hedge, putting on 75–90cm a year. That makes it brilliant for quick privacy, but it means you must keep on top of it — two or three cuts a season — or it quickly outgrows its space and becomes hard (and expensive) to manage.

When to cut a Leylandii hedge

Trim between spring and early autumn, while the hedge is actively growing, with the main cut after birds have finished nesting. Avoid trimming in drought or harsh midday sun, which can scorch the cut foliage.

The golden rule: never cut into old wood

This is the single most important thing to know about Leylandii. Like most conifers, it will not reshoot from bare brown wood. If you cut the sides back beyond the green growth you will be left with permanent dead, brown patches that never green over. Always trim within the green, and decide your final width and height early — then keep it there.

How to cut a Leylandii hedge, step by step

1. Set a string line for a level top.
2. Keep it narrow, with a slight batter (wider at the base) so light reaches the bottom and it stays green to ground level.
3. Trim the sides first, then the top, always staying within the green growth.
4. Clear the clippings and water in dry spells.

Can you reduce the height?

Yes — the top can be cut lower, as long as green growth remains below the cut. It is reducing the width into old wood that causes permanent bare patches. If your Leylandii is already too wide, the realistic options are to live with it, or remove and replace.

High hedges and the law

There is no fixed legal height, but under the high hedges rules a neighbour can ask the council to act on an evergreen hedge over 2m that blocks their light. Keeping it well trimmed avoids disputes — see our guide to hedge law and boundary hedges.

Want less maintenance?

If the upkeep sounds daunting, Thuja (western red cedar) gives a similar dense evergreen screen but grows more slowly and, unlike Leylandii, can regenerate from older wood. Browse our Leylandii hedging and conifer hedging ranges.

FAQs

When should I cut a Leylandii hedge?
Two or three times between spring and early autumn while it is actively growing, with the main cut after birds have finished nesting. Avoid trimming in drought or harsh midday sun.

Can you cut a Leylandii hedge back hard?
You can reduce the height into green growth, but never cut the sides into the old brown wood — Leylandii does not reshoot from bare wood and will be left with permanent dead patches.

Will Leylandii grow back if cut too far?
No. Unlike yew, Leylandii will not regenerate from old brown wood, so any cut that exposes bare wood stays bare. Always trim within the green.

How often should you trim a Leylandii hedge?
Because it grows up to 75–90cm a year, a Leylandii hedge needs cutting two or three times a season to stay dense and under control.

About the author: Paul Watmore is a director at Grasslands Nursery, a family-run plant nursery near Knutsford, Cheshire, growing hedging, pleached trees and specimen plants since 1984. Meet the team →