When is bamboo a countable noun and an uncountable noun?

When is bamboo a countable noun and an uncountable noun?

"Bamboo" is the same as "water", "milk" and so on. It is an uncountable noun in itself. It can only become countable when the quantifier is added in front of it. But note that the quantifier is added with "s" instead of the noun itself
Two pots of water
three buckets of bamboo
a bottle of milk