We have a row of quite mature leylandii trees as a privacy screen which we wish to have shortened and trimmed, to turn into more of a hedge. Part of it was already done this summer but when are the good and bad times to do this?

I had theorised spring so it has the whole year to grow back?

  • The best way to prune them is cut them down to ground level with a chainsaw, then use a flame thrower on the roots, IMHO. But seriously, it doesn't really matter - any time of year is OK. Just beware than if you cut off half a branch, the remaining half will probably die back and leave either brown dead foliage, or a hole in the screen.
    – alephzero
    Commented Sep 10, 2018 at 17:01
  • I thought as long as you didn't cut back to the brown wood, it would be OK? I'm not sure how cutting half the branch is different to trimming a hedge, could you clarify?
    – Mr. Boy
    Commented Sep 10, 2018 at 17:06

1 Answer 1


The recommended time for cutting back mature leylandii hedges in the UK is two or three cuts between April and August, so its a little late now, though you could risk taking some off if you're desperate. More information here https://www.rhs.org.uk/advice/profile?pid=596

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