Trees

[hope3fully]

when trees reach a certain age do they stop growing ?

[Chipchopper]

Depends on the species or tree. They can vary immensely.
From memory, it is theoretically possible for a Californian redwood tree to attain a maximum height of approx 420 feet, above that it can no longer conduct nutrients and water.

[KARL]

As already said, different species vary. In principle, all of them have a certain (but varying by species) maximum height beyond which they do not grow but they will still keep gaining in girth. On the other hand lots of trees exhibit a maximum life expectancy and they simply die sometime around then even though all other conditions remain favourable for their continued survival.