Clean the rose hips, rinse and drain well. Cut fruit in half lengthwise and mash in a saucepan with a potato masher or ladle.
Pour the rosehip mixture into a prepared 2-liter glass jar. Sprinkle the rock candy in between.
Pour the rum over it, it must completely cover the fruit mass. Close the jar and place it in a sunny window, where the contents should infuse for 14 days. Shake the jar from time to time.
Leave the jar at room temperature for at least 1 month. Pour the contents of the jar through a gauze cloth. If you want the liqueur to be completely clear, you can additionally strain it through a coffee filter.
Fill the rosehip liqueur into small bottles and let it rest for 3 months. At the same time it should stand cooled.