Are there different times of year that trees are dormant?

The topiaries are green you're around. He has other deciduous trees that do lose their leaves there's always something to see all four seasons

Mostly green.

Mostly green year round. Some areas are planted with annuals that peak at different times.

I believe most of not all of the trees are green year round.

A lot of the topiaries are junipers so they stay green all year.