can anyone help?
you have two options.
The easiest one is to apply a material to the wall which simulates the hedge appearance. You can use a bump mapping texture to get some relief.
Another option is to use a Lands Parterre, but it requires some work toadjust the parterre surface to each side of the wall.
It would be great that Lands offers, in the Wall properties, the option to apply a parterre to get the hedge look. But this is not possible in the current version.