Cherry plums are generally in season from early summer, typically around June, with some varieties ripening as late as September. The season can extend through the summer months and sometimes into early fall depending on the specific variety and location. In some cases, cherry plums can be available from as early as May and up to November in favorable conditions. The fruits are usually harvested once they have reached their ripe color, which varies by variety. Cherry plums tend to be among the first plums to ripen in the season, often ready before other types of plums.