Most flowers just drink through their stems however hydrangeas drink through their faces just like hellebores and phaly orchids do!
By bathing them they get a good drink and don't wilt - especially important if they are being used for a wedding on a hot day!
They need a lot of water to stay perky and crisp so leaving them a a bath of water for a couple of hours will do the trick!
Once you have bathed the hydrangeas cut the stems at a 45 degree angle before you put them into a vase or bouquet.
Remove any foliage that is below the water line and keep them in a cool room out of direct sunlight where they can thrive and live a long life or look beautiful in a bouquet!