Question
I have two of these plants, one looks great, but the other has started getting dead limbs on it. These are not tree Hibiscus. Both still blooming. Is there any thing I can do to help this plant. I can not see any cause for this problem. Thanks for the help.

Answer
Hi Tom,
Thanx for your question.  When did you notice the limbs were dying on your hydrangea?  Did you notice when the leaves started wilting?  Did you check closely for any signs of an insect or fungal parasite?  Approximately how much of the plant is now dead?  The hibiscus you're talking about is perennial in a cooler zone (zone 7 and below) and the plant dies to the ground every year, correct?  Hibiscus moscheutos is most likely the plant.

http://www.floridata.com/ref/h/hibisc_m.cfm  This is a link to more information on the hardy hibiscus - Hibiscus moscheutos

Actually, it's not uncommon for the shrub to start dying back in late August to early September.  The farther north in Zone 5 you are, the quicker this will come about.  A neighbor of mine has some that look horrible now as they do every year about this time.  They're fixing to go to sleep for the winter.  Most likely, they're fine but holler back if you have more info.

I hope this helps.
Tom