Question
I have a large Rose of Sharon tree/bush.  I believe it is approx 20 years old as that is how old the house is (2nd owner).  There were two plants but one split at the ground level and had to be removed.  The remaining one is multi-trunked with a spread of about 15 ft and approximate 20 ft tall.  There are very many blooms which start in May and last most of the summer.  They are purple to pink. I could send a picture if helpful.  The tree sheds many of its bulbs (overwatering?) but there are so many it really doesn't matter.  With so many blooms it tends to bend most of the branches.  I am afraid it will split the trunks and I will lose the tree.  Questions:
1.  When is the best time to prune?  I live in Memphis and it gets full sun.
2.  I want to retain as much as possible the bushy tree look.  It has approx 8 "trunks" at ground level and at 5 feet as many as 15 limbs approx3-4in diameter. 5-20 is the canopy.  So how much should I prune it back?  and do I start from the top  or the bottom?  Obviously I know little about pruning.
Thanks you so much for your help
Dave Johnson

Answer
Dear David,
 This fall after the bush has finished blooming you can trim it back to whatever height you desire.  Also you should "thin out the main stems".  Go into the base and find the biggest stems and cut them way back-you can do this to about 1/3 of the base stems.  These are called "mother stems" and without them, the others will have more room to grow.
 I trim all my Rose of Sharon to about 3' in the fall and they branch out beautifully by mid July (zone 5)when they are about 5'.  The 2 I have in back I only trim to 5'-I want them taller.

You should keep some klind of mulch around the base of the Rose of Sharon.

Sijka