I have a large number of arborvitae planted 15 years ago alongside the street side of city lot for privacy. I have let them grow to about 10-12 feet high but am now faced with too much shade on this east side of my property. I need more sunshine for my flowers but the arborvitae are too tall. I know I should have trimmed them all along but I liked the privacy they provided me from the street and sidewalk so I just let them grow.
Now that they are so very tall, I would like to cut them down to about 6 feet. Can I cut them down without damaging or harming them?
Cutting off that much (about 50% of the height) will be challenging to do without leaving a bare top. The interior of arborvitaes do not have dormant buds to push out and make new growth. It will take awhile for the new growth from below the cuts of branches that you cut back (head) to grow out and cover the bare top. It would have been better to trim them back to maintain height when they were smaller instead of a drastic pruning to reduce height now, although you explained why you did so.