Love peaches, nectarines, and plums but the ones at the store are as hard as rocks? Try this easy trick to ripen fruit faster. Place the peaches, plums, or nectarines that you wish to ripen in a paper bag. Add a ripe banana to the bag. Bananas give off ethylene gas which will encourage the other fruits to ripen more quickly. Roll up the top of the bag firmly so that it won't unroll and set on the counter. Check the fruit once a day for ripeness.