Hard prune large yew hedge

(Question)

Hello,

I looked through the ‘find it here’ and didn’t see this asked previously and am therefore seeking advice.

We have large yew hedges on each side of our yard. As we inherited them with the house I’m going to hazard a guess they’re at least 10 years old. About 5′ deep and 10′ tall, run a length of approximately 12-14′ long.

They are quite healthy and we enjoy the privacy they give us as well as providing a home for numerous sparrows!

The drawback is they are getting much too large and are taking over useable yard space. I know these are resilient plants and I understand that if I prune hard one year the hedge may appear bald for a year or 2.

However can I be a bit ruthless in cutting these hedges back? I was going to take in one vertical side about 1.5 – 2′ one year and take down the top 2′ the second year. I was thinking mid March is when I would do the pruning. The 2nd vertical side faces the neighbours and those sides have been well maintained so I don’t need to worry about those!

As well, due to the sheer volume of the hedge, and the diameter of some of the larger stems can I use a chainsaw?

Any advice on taming these lovely yet much-too-big hedges?

Much appreciated!

Unfortunately I don’t have a picture to show the full scale of the hedges but hopefully this gives you an idea.

(Answer)

Thank you for contacting the Toronto Master Gardeners regarding a rejuvenation pruning for your yew (Taxus spp.) hedges.  Yews differ from some other evergreen shrubs in that they will sprout new growth from old wood and will tolerate significant pruning.  As you mention, it may take a couple of years for the pruned areas to fill in and give you the desired look of the shrub.  It sounds like you have a good plan in terms of beginning with one side and then tackling the top the following year.  A rule of thumb is not to prune more than 1/3 of the shrub at a time and your plan meets this recommendation.  Late winter / early spring is a good time to prune your yews – just before the fresh flush of growth begins in the spring.

In terms of pruning tools, loping shears and a pole pruning saw / shears (to reach higher areas) will give the best, cleanest cuts.  If some of the older branches are too thick for these tools, a chain saw or gas powered hedge trimmer (generally more powerful than electric) can be considered.  The latter two implements may chew up the woody branches a bit and trimming any badly mangled ends with a hand saw or lopers can help prevent entry portals for disease.  Once your rejuvenation pruning is complete, hand shears or an electric trimmer can be used to maintain the shape and size you want.

Another consideration is the shape of your hedge.  Pruning so that the top of the hedge is a bit narrower than the bottom will help sun reach the lower branches and result in better health and growth.  The link below for Michigan State University includes a photo of the desired shape.  Be sure that your hedges get adequate water and nutrients throughout the growing season to help them tolerate the rejuvenation pruning as best as possible. Yews do best with medium moisture and good drainage – they don’t tolerate soggy, wet conditions very well.  Mulching with 1-2 inches of good compost will help to optimize their soil conditions.

Best of luck with this project!

https://www.canr.msu.edu/news/pruning_evergreen_shrubs