Question
I received a hydrenga for Mother's day.  It came from Target.  Can I plant this type outside?  We have a Pin Oak that is about 12 yrs old.  We noticed this weekend the leaves are starting to wilt.  Is there a disease causing this?  can it be treated?

Answer
First, yes you can plant the Hydrangea outside in a protected area away from the wind (since Hydrangeas will be damaged by winter winds). Hydrangeas prefer filtered sunlight over direct sunlight or dense shade. Fertilizer is not recommended for the first year. They prefer moist, well drained soils. Do not overwater them, as this will drown the root systems.
As to the Pin Oak, if the wilting is throughout the tree, then I would look at how much water the tree is receiving. Since we have not had significant rainfall in a few days, it could be in drought stress. Was ther any disturbances around the tree lately? Any digging of any sort that would have interfered with the trees root system? Another possiblity is that there are compaction problems around the tree, which is limiting the root growth.
If the wilting is localized, then you need to see if there are any galls on those branches. These galls look like ping pong balls on the branches. This damage is caused by a wasp that stings the branch and inserts egg into it. The larval wasp irrtates the branch, causing the gall and resticting the nutrient flow to the leaves. These galls would need to be pruned out.
In the case of the drought stess or any type of root damage, put a soaker hose around the base of the tree and run the water for a few hours every day. As far as the galls, prune them out and fertilize the tree to help replace some of the nutrients that it is losing.