Table of Contents
Best Time to Trim Yew Hedges
To keep a mature yew hedge tidy with only one cut per year, the ideal time is September-October.
How to Prune a Yew Hedge 
You do need to clip yew plants to make them bushy – shortening side branches causes them to produce the twiggy growths that help make a yew hedge the densest and most elegant evergreen hedge there is.
Pruning Yew Hedges immediately after Planting
On planting (October-March) cut back any side growths that straggle so you leave the line of yew hedge plants looking reasonably straight sided. In a perfect world you will leave the branches at the bottom of the plant just a little longer than the ones near the top, so your hedge has slightly sloping sides.
Do not cut the top of the plant until…
The uncut growing point of a young yew hedge plant is vigorous, growing up to 40cm in a season.
Once cut, your plants become bushier and never regains the same upward vigour, growing only 10cm or less each year.
When the growing tips reach about 10cm over the height you want, cut them off.
Pruning Yew hedges in later years
Yew is among the easiest and most forgiving of hedges. It makes new shoots even from centuries old wood, so pruning mistakes will grow over in time.
In the early years, the more often you clip the side branches, the bushier your yew hedge will become.
We would recommend gently clipping in April, July and October for the first couple of years at least (always leaving the growing point alone, of course).
Keep forming the hedge to a tapered shape to allow light to get to the lower branches.
Should you wish to drastically alter the shape or height of your yew hedge – for example cutting an archway through it, or significantly reducing the height, carry out the surgery in mid-winter when the plants are semi-dormant.
If you have an overgrown yew hedge and you need to reduce its width, cut one side back very hard indeed one winter, right back to the tree trunk in the middle of the hedge and reduce the other side the following year.