Hedge on the property boundary (in NRW)

Plants stand directly on the property boundary with the neighbor and we currently have a dispute about how much the plants may be trimmed in height.
What is the legal situation? Unfortunately, most Google search results only refer to topics about maintaining distances, but the plants have already been there for more than 10 years.

In NRW, the hedge is probably a shared enclosure of both parties. In that case, no distance regulations apply – it is like a fence.

But what about trimming in height? Am I allowed to just do that? Or is the shrubbery considered joint property that I am not allowed to cut?

The height is probably limited to 2m. You are not only allowed to trim it, but according to neighbor law, you are even obliged to do so. If you have a gardener do it, the neighbor must also contribute.

What height and extension do you wish for and what does the neighbor wish?