The first trim of spring does more for a hedge's shape than any other cut of the year. The trick is that the hedge tells you when it is ready, and the calendar does not.
Read the growth, not the date
Wait until you can see roughly 2 to 3 centimetres of fresh, lighter-coloured growth pushing out past last year's foliage. That is enough new tissue for the hedge to answer a cut with dense branching instead of a stalled, patchy response.
On most Auckland properties that flush arrives from mid to late September and runs through October. Cut before it, and you are trimming last season's wood, which does little for density. Leave it past October and you are fighting several weeks of loose growth, closer to summer stress than the plant would like.
Why this one cut matters so much
Cutting the growing tip removes the point that was suppressing the buds below it, and those buds push out sideways instead of upward. That is the whole mechanism behind a dense hedge. More cut tips early in the season means more side branching, which means a tight face that holds right through summer instead of going leggy and open.
Two things that go wrong
- Cutting into old wood. This is a light shaping cut, not a winter renovation. Griselinia, pittosporum and photinia reshoot from older wood reasonably well. Conifers such as macrocarpa and most cypress hedges carry live buds only in the green outer growth, so a cut past this year's flush leaves a gap that will not fill back in. When in doubt, shape only the new growth.
- Trimming blind. Native birds are absolutely protected under the Wildlife Act 1953, and it is an offence to disturb or destroy a protected bird's nest without lawful authority. Nesting runs from around September to February, which overlaps the trimming season almost exactly. Look through the hedge first, and work around any active nest until the young have fledged.
Our approach
We time a hedge client's first spring visit to that early growth flush rather than a fixed month, because a week either side is the difference between a hedge that fills in evenly by December and one still catching up at Christmas. Hedge and small tree work up to four metres, quoted per job.