Rejuvenating Old Boxwood Shrubs
I'm a master gardener and I also maintain gardens professionally. I have a customer that has boxwood shrubs that are about 35 years old or even older. I don't believe they are English boxwood as they do not have the order of an English boxwood. They get morning sun and afternoon shade. They have new growth in the inside branches. They are so gangly looking I think it would be best to cut them back to the size as to where the new growth is coming out. What do you think?
Montgomery County Maryland
The shrubs in the photo look like boxwood but we cannot say for sure. There are several types of pruning methods for boxwoods - thinning, shearing, and heading back (restoring overgrown boxwood). You will have to decide on your goal.
The best method for pruning English boxwoods is thinning. This allows the center of the plant to receive adequate sunlight and good air circulation. The best time to thin boxwoods is December through February. The temperature should be above freezing.
Shearing - An example of this is if you are growing boxwood as a hedge. Best time to shear is in early June. A second light pruning may be needed in July.
If reducing in size drastically, this requires a two step approach and should be done in the early spring. If cutting only a small amount, prune at one time. First cut one half of all the large branches. The second year the remaining branches would be pruned in the same manner.
You can remove dead wood at any time.
Since you are maintaining gardens professionally, you may want to look at The Boxwood Handbook, Third Edition by Lynn R. Batdorf.
Also, the American Boxwood Society has some publications on boxwood http://www.boxwoodsociety.org/