Dear Heide: Oak Leaf Hydrangea is going to be a large shrub as it matures, reaching 6 or more feet in height and wide. If it is planted too close to a wall it is naturally going to reach out away from the wall. You can maintain the size with proper pruning, but eventually it may get too big. You should not have to wrap the Hydrangea . Prune after bloom back down to a smaller branch or bud. Late season pruning will remove the flower for the coming year.
Sincerely, Richard