2. The biggest part of choosing hydrangeas to dry out is making sure you pick ones that have already started to dry just slightly. There are several indicators you can look for. The first is color. With limelight hydrangeas, the ones that are not ready are a brighter white while the more mature flowers are a softer green. Second, feel the flowers. The ready hydrangeas will feel almost papery. Lastly, listen to the sound the flowers make as you run your fingers through them. Ready hydrangeas sound like the petals are rustling together while the others make hardly any sound at all.