When and how long are they getting sun?

I normally water them every other day early in the morning. They get like six to seven hours if sun each day:)

Hi I too am in zone 10 (California). I just brought a Hydrangea also. Have learned mostly from reading on this web site. Here in zone 10 plant Hydrangeas where they will get morning sun and afternoon shade. Maybe yours are getting too much sun? I do plant drought tolerant plants when I can; but can't resist the occasional thirsty one, like Hydrangeas. Though I think I have a Limelight,no label from Costco. Blooms are pink and light green. My problem is more of a design issue. My back yard is a good site as far as sunight ( North side morning sun and filter afternoon shade deeper shade towards evening. But it is raised beds about 2 ft or so deep. Deeper in some areas but I would have to transplant a bunch of new plants including a Mandavilla Vine I am afraid won't survive the move. I can't picture how the Hydrandea would look in the rectangle shaped bed and would it be too big for the space? Would I be better off putting it out front (south) but where it would receive some shade from small garden trees and pine trees a few ft away?