Posted: 02/11/2016 at 08:30
although hydrangeas will grow in containers they really need the depth and moisture of being in the garden soil.
Can you plant it out?
You said "old" hydrangea so it will be hungry, thirsty and congested in that pot. You could repot, feed and mulch but, know what? Life is too short. Get rid of if and treat yourself to something new for your container