To ripen — to become fully mature (as fruit or grain), often used intransitively and similar in meaning to 熟す.
今年は日当たりが良くて柿がよく熟れる。
This year, with good sunlight, the persimmons ripen well.
桃の木は暖かい場所で早く熟れる傾向がある。
Peach trees tend to ripen earlier in warm places.
リンゴが十分に熟れるまで収穫を待とう。
Let's wait until the apples are fully ripe before harvesting.