An article from the newspaper on the hedge trimming issue:
...The pruning claim also does not become statute-barred. In Bavaria, there is no pruning claim, but only a claim for the removal of planting near the boundary. However, in these and many other federal states, the problem arises as to how often the pruning to the maximum permissible height can be demanded, and in some federal states it also depends on when this claim becomes statute-barred. Because in most neighboring law statutes no pruning can be demanded after five years. In Bavaria, the similar question is whether the neighbor, in order to avoid the obligation to remove the hedge, has to prune back repeatedly and whether after five years of pruning the hedge may grow into the sky due to protection of existing rights. The Federal Court of Justice has now taken up these issues. In decision V ZB 72/11, the court settles, applying the Saxon Neighbor Law, that the neighbor can generally demand not only a single but twice annual pruning to 2 m, namely during and after the growing period. (Exception: e.g. Baden-Württemberg or Saxony). Furthermore, after each regrowth beyond the maximum permissible height, the pruning or removal claim (e.g. Bavaria) arises anew. Statute-barred status therefore only occurs if the hedge planted near the boundary has not been cut back to the permissible measure for more than five years. Therefore, it should always be ensured that the neighbor cuts the hedge in height at least every five years. (In North Rhine-Westphalia, by the way, six years must elapse before the claim becomes statute-barred.)