Key takeaways
- Many broadleaf hedges recover from a hard cut back if it's done in stages.
- Most conifers won't regrow from old, bare wood, so cutting them too hard leaves permanent gaps.
- Cut one side first, the other side the next year, then the height.
Which hedges recover
The Royal Horticultural Society lists hedges such as box, holly, Lonicera nitida, beech, hornbeam and yew as tolerant of hard renovation. These can be cut back by up to half their height and width in one go.
Many other broadleaf hedges cope with a cut back too, but how well they recover depends on the plant, its age and its health. That's why cutting back in stages is the safe approach.
Which ones don't
Most conifers, apart from yew, don't respond well to renovation. Leyland cypress and other cypress hedges often won't grow back from bare brown wood, so a hard cut can leave a permanent hole. With these, it's usually better to keep trimming lightly or plan to replace the hedge.
Cutting back in stages
The RHS recommends spreading a big renovation over two or three years:
- Year one: cut back one side hard, to a little less than the width you want. Trim the other side as normal.
- Year two: cut back the other side the same way.
- Year three: bring the height down to just below where you want it.
If the hedge is slow to recover after a stage, wait another year before the next one.
When to do it
Evergreen hedges are best renovated in mid-spring, once they're actively growing. In Auckland that's around October. Deciduous hedges are done in winter while they're bare. Lilly pilly is different: trim it in winter to reduce the risk of myrtle rust.
Aftercare
- Mulch around the base after each stage to help regrowth.
- Water during dry spells in the first growing season.
- Only feed if regrowth is slow.
- Check for nesting birds in spring before you start, and wait if you find an active nest.
Not sure what you've got?
Send me a photo of the hedge and I'll let you know what it is, how hard it can go and how many stages it's likely to take. See hedge trimming or get a free quote.