Posted: 02/08/2016 at 13:53
If your garden is south-facing your hydrangeas may need some extra water if they are in full sun, especially if they are recently planted. On the whole, though, if they wilt they need water.
Although I'm not suggesting you do it, I remember a TV gardener years ago (Percy Thrower?) suggesting that weekly watering was plenty, be that rain or by hand.