We have some fabulous hydrangeas which are overcrowded, and against the north-facing wall of our house, which is in the shade of the sun most of the day.
The soil here is alkaline and full of limestone pebbles & cobbles. Our hydrangeas vary in colour between purple, violet and pink. They are flowering well. They may have been treated or fed before we moved here, but not for the last 15 months or so. Our garden is free-draining, but being on the side of a hill, in times of heavy rain we get the occasional lake quite close to the house!
We are intending to have some steps built, which probably means we will have to move the hydrangeas this autumn/winter. I have read that they don't like full sun, so I will probably put them lower down in the garden, in the shade of a high laurel hedge (but not too close to it).