Hydrangeas have woody stems that need to draw water for maximum vase life. If a blossom wilts prematurely, remove it from the design, recut the stem at a sharp angle and place in hot water ( as hot as your hand can stand) for at least one hour. The flower should be revived and ready to take its place in the design. For best results keep the water level in their vase full. This method may have to be used anytime the hydrangea is out of water for any lenth of time.