Hah! Happened to us once a few years ago. What stings more is the stolen time spent trying to grow those shrubs into a nice hedge. So when we replanted, we dug a hole, poured a block of concrete with a length of rebar going into the concrete and running along the base of the hedges, with hose clamps around each plant and the rebar.
Now, if some a-hole wants to steal them, they need to have not sold their screwdriver for drug money and have the patience to unscrew each one.