Harvest rose petals early in the morning when the rose blossoms are fully open and the dew has dried.
Clip off the entire rose blossom.
Pull the complete rose petals gently from the blossom and place them directly onto the window screen in a single layer.
Place the window screen in a protected place that is out of direct sunlight and wind. They must have some indirect air circulating around them to dry them, however.
Monitor the drying process. The rose petals are not completely dry until they are crisp enough to snap in two. Do not stop the drying process before this point or the petals may mold.