An edger has a main frame that can be advanced controllably relative to subjacent terrain and a cutting assembly on the main frame. A drive rotates the cutting assembly around a first axis. The cutting assembly is configured to produce a trench in underlying terrain as the cutting assembly is rotated by the drive in operation. The cutting assembly has a perimeter edge with a contour extending over an axial distance. A shielding assembly defines a radially inwardly facing surface that resides radially outside of the perimeter edge of the cutting assembly. The radially inwardly facing surface has a shape that is at least nominally matched to the contour of an axial extent of the perimeter edge of the cutting assembly so that as the cutting assembly rotates the radially inwardly facing surface and perimeter edge of the cutting assembly cooperate to each avoid buildup of foreign matter on the other.