sazreti

1. (of fruit) to ripen
   Paradajz je sazreo za nedelju dana. — The tomatoes ripened in a week.
   Grožđe još nije sazrelo. — The grapes haven't ripened yet.
2. (of a person) to mature; to grow up
   Posle studija u inostranstvu mnogo je sazreo. — He matured a lot after studying abroad.
3. (of an idea, conditions) to mature; to become ripe; to be ready
   Ideja o selidbi je polako sazrela u meni. — The idea of moving slowly took shape in my mind.
   Uslovi za promene još nisu sazreli. — The conditions for change aren't ripe yet.

The imperfective is sazrevati.