Posted: 18/06/2017 at 08:00
If they are in pots could you not move them into a shadier area ?
Blue flowering Hydrangeas need an acid soil to grow in or else they will change colour. What compost did you use to pot them up in ?
If you didn't use ericacaious compost you could try keeping the colour blue by feeding regularly with ericacaious feed and Hydrangea colourant.