Pruning Overgrown Arborvitae
I have a stand of arborvitae that have overgrown my deck and the adjoining stairway. Each arborvitae is about 20' tall and about 4' wide. They've overgrown onto the deck by about a foot over the rail. Is there a way to prune these back without leaving a massive bald spot that never grows in?
It appears that you will need to prune these evergreens back to the woody stems in order to get them off from the deck. That is not a good idea. The most you can do is selectively prune it. That may not take them back as far as you want them.
These evergreen trees will not form new buds on old wood. So if you cut back to the brown, aged stems, it won't grow back.
I am including a link to information from UMassAmhurst. http://extension.umass.edu/landscape/fact-sheets/pruning-needled-evergreens
There is a brief video available featuring Bert Cregg, MSU, Departments of Horticulture and Forestry, showing how to prune evergreens that will not re grow from the old wood. While the video is informative, The publication and advertisements are not endorsed by MSU. http://www.finegardening.com/video-pruning-arborvitae-junipers-and-chamaecyparis
I hope this helps.