Ocado Ripen at Home Plums. These plums are really versatile as when firm, their tart flavour makes them perfect for use in baking your favourite desserts such as crumbles and pies. Once fully ripe, they become sweeter and are delicious eaten as a healthy snack on the go.  These plums ripen best at room temperature. To test if they're ready to eat, press gently with your thumb - a ripe plum should feel slightly soft to the touch. Want more long lasting fruity favourites? Search 'Ocado ripen at home' to fill up your fruit bowl.