The freeze caused damage to the leaves but it should not have affected the roots so... you still have a healthy shrub. Of course, you will have some ugly leaves as a result of the freeze... but no real big problems per se.

You could prune any completely browned out leaves and the worst looking but somewhat green leaves and let the others stay the course. See if the plant puts out new leaves in a month or so. Personally, I would crunch the browned out areas with my hand to remove the dried out parts and then check again in a month to see if there is something else that needs to be tweaked.

luis_pr - I really hope you are right. According to Penn State Extension's publication Hydrangea Diseases, powdery mildew causes leaf mottling and so do viruses. I will look under the leaves today for powdery mildew to rule that out. The brown edges I can see being due to the freeze. But would a freeze cause the yellow mottling? I love this bush and do not want to lose it! Thanks for your help.

Winter damage can turn leaves yellow/brown out or can turn them all dark green to almost black but, pests and viruses would be more suspect on the yellow mottling. PM can sometimes be hard to diagnose until symptoms are more obvious. It creates more yellow roundish spots and you would see more impact under the leaves in the form of pustules. Have you checked for spider mites already? A heavy infestation can produce mottling on leaves too so I normally suggest virus problems (and getting confirmation from agric extension offices) when there is no spider mite infestation.

Here is a link that might be useful: {{gwi:1001387}}

This post was edited by luis_pr on Mon, May 20, 13 at 11:59