Posted: 24/08/2016 at 09:06
Wakeshine, I don't think you have done anything wrong.....except too much direct sunshine perhaps
however, those brilliant blue flowers will not last forever.....they do and will fade now and hot sun will not have helped. Blue colourant will not make a difference at this time of year. Ericaceous compost does help maintain the blue so that is fine.
Move to shadier spot, water well to help prolong flowers in pristine condition but remember we are entering autumn and many plants, incl hydrangeas, are starting to prepare for it.
(Sad, isn't it, to think about autumn? )