My grandma received a potted hydrangea as a gift. She had me plant it in the garden in front of our house this summer. I planted it according to the guidelines for the most common type of hydrangea (mophead I believe) because I don't know what type it is and I followed the guidelines for our zoning area, which is 9. We live in Sacramento, California. The problem is that the bush is not taking well to the move outdoors. The leaves show signs of over watering (drooping and yellowing) but the only time it perks up is if I give it water like it's dehydrated. I don't know what to do.
The soil does look dry. Regular watering for new plantings is important so the plant can become established.
Adding 2 to 3 inches of hardwood mulch will help with moisture retention.
Here are some links for you to refresh you on the care requirements.