I have always wanted to figure out how to dry Hydrangeas properly, so the petals keep their shape and color. Turns out the trick is in the timing. It has to be toward the end of the season, October - November, when blooms start drying slightly out and changing colors, but still are in good shape. Apparently, this cannot be achieved with store-bought Hydrangeas, as they are just too fresh and full of moisture. Once your plant is ready, cut off the flowers, remove leaves off the stems, and display them in a vase filled with water. The water will evaporate with time and this will allow for the flowers to stay fresh and dry out naturally, preserving the color. In the end, you will have beautiful dried arrangement that will last you for years.