Rose of Sharon
I have a 20yr. old Rose of Sharon tree. It still produces beautiful purple flowers, but the branches are getting leggy and covered with moss (you can't rub the moss off, it's imbedded in the branches). I'd like to cut it down, but my husband would like to keep it. Can I trim it down to where it will grow back more full? What is your recommendation?
Skamania County Washington
The average lifespan of a Rose of Sharon shrub is 20-30 years. There are several ways you can prune it. First, go out and cut off all the damaged, diseased, and dead branches. You can do that at any time. If you want to keep the general size of the tree and make sure you have flowers in the current season, you can prune back up to 1/3 of the branches in late winter before leaves appear.
If you want a smaller bush with larger blossoms, and are content to wait a couple years for it to bloom again, you can try rejuvenation pruning. This is where you cut all the branches back to 6 inches from the ground in spring before it leafs out. However, I am not certain that a 20-year-old shrub could deal with this kind of stress. Good luck! Here's more information: https://njaes.rutgers.edu/fs1221/