Oak, Maple, Pine: Seedling 30, Young 60, Mature 90, Elder 60, Ancient 30
Cherry Blossom (+25%): Seedling 24, Young 48, Mature 72, Elder 48, Ancient 78
Willow (+15%): Seedling 27, Young 52, Mature 78, Elder 52, Ancient 61
So a Cherry reaches Ancient (x1.6) at watering 192 instead of 240, and stays there for 78 waterings instead of 30.

One small detail: the life is counted in waterings, not days. If you skip a day, your tree doesn't get older, it just waits for you. Watering once a day, that's about 270 days.

The full rule is in the FAQ under "Do trees live forever?".