Castle Green Oak trees

Question

Can I top and how to trim a “Castle Green Oak” tree?

Answer 1

It looks like this is a relatively new columnar oak variety. Here is more information about these trees:

https://www.gardeningknowhow.com/ornamental/trees/oak/columnar-oak-trees.htm

Letting the tree grow in its natural shape is the best option, and topping is to be avoided. But, here is an alternative approach recommended by a university extension agent for someone who had a similar question:

https://ask.extension.org/questions/249500