brooklyn1 wrote:

When I planted a hedge on the yard line, I made the assumption that
I would trim the neighbors side also. It was my choice to plant it.
I do ask before I enter their yard to trim it.

I'd not recommend planting a hedge that necessitates relying on the
owner of the adjoining property trimming those portions that grow on
their side or to cooperate in any way. You may get along with the
present neighbor famously but there are no guarantees that they will
still be your neighbor next year or even tomorrow, or that you don't
have a falling out.

If they choose not to let me come in to prune it, then it's their problem.
Hasn't happened in 30 years.