That method of fertilizer application is an interesting idea. My only concern would be that some of the liquid-based fertilizer might migrate away from the target area and fertilize surrounding plant life, such as grass. You might wind up seeing a difference in the quality of the grass in the immediate area of the hedges.

BTW, when you were replanting, did you come across a grille emblem for a 2007 Tahoe? Just let me know.