If you have ever had the misfortune of biting into an unripe plum, then you no doubt felt the keen disappointment and experienced the sour taste of fruit that is not yet ripe. By contrast, a ripe and juicy plum is a tasty treat. If you have harvested plums from a plum tree that are not ripe, it is a simple process to hasten the ripening and get the plums ready to eat.
Place the unwashed plums inside the brown paper bag. Fill the bag not more than half-full of plums.
Fold the top of the bag down once or twice to secure it.
Set the bag aside and keep it at room temperature for one or two days.
Open the bag after two days and check for ripeness. Ripe red plums will be almost completely red and ripe black plums will be almost completely black. The plums should be soft when you press on them gently and should smell like sweet plums.