QuestionsHow to growTrees and ShrubsPruningwhen to cut back leylandii hedging 0 Vote Up Vote Down maria fallon asked 14 years ago we have a 12 foot leylandi hedge all round a half acre site, which was not cut back and shaped last year. we are having trouble getting somebody to cut it for us this year, what is the best month for cutting such hedges? 1 Answers 0 Vote Up Vote Down Gerry Daly Staff answered 6 years ago It is normally done in late August or September as it will stay neat for the longest period when cut at that time.