By: Sandy Feather ©2009
Penn State Extension
Q. I have three Yew shrubs planted in my back yard. They were planted in a row years ago, and now are so overgrown that they look like one big evergreen shrub. They are 20-25 feet tall and 15-20 feet wide. I do not want to remove them since they are home for so many birds, and I enjoy seeing the Yews from my kitchen window. Can I cut them back significantly to get them down to a more manageable size?
A. You can prune healthy yews (Taxus spp.) back quite severely with no problem. You can easily reduce their size by one-half to three-quarters. Such severe pruning is best done in early spring so they have spring and summer to recover. They will respond by throwing up a lot of new growth. Be sure to use hand pruners, limb loppers and pruning saws rather than hedge shears to reduce their size. Where possible, remove extremely long secondary branches at their point of origin on a main stem.
Most branches will be too thick for electric hedge trimmers, so it's a job for loppers and a saw. March is the best month for heavy pruning in the Northeastern US
Even if you keep your yews sheared into a hedge, you can achieve significant size reduction while making fewer cuts by pruning this way. Where possible, cut to an outward-facing side branch or bud – this opens the centers of the plants to good sun penetration and air circulation.
Remove branches that grow back toward the interior of the shrub to eliminate crossing branches. Even yews sheared as hedges should be pruned this way every three or four years to encourage healthy interior growth.
GASP! Severe cutting-back is rather shocking, but new growth will emerge from adventitious buds along the remaining branches. It may be 2 to 3 years before the Yew appears whole again.
You will not be able to see buds along thick, old stems – they are present under the bark. You will see where they are when new growth begins to sprout. The new growth should stop by about mid-July, which is when you should try to shape it a little, especially if you want to shear them into a hedge. Since you could not see where the buds were until the new growth started, you will notice a lot dead stubs where no growth is occurring. Be sure to prune them back to just above where new growth emerges from the stem.
By late June, new growth (from adventitious buds) has begun to emerge from the remaining branches on the Yew stump.
You might want to give the yews a little extra care this summer by watering when we get into very hot, dry weather. All that new growth will use more water than the mature stems you are removing. An inch of water a week is ideal.