Abstract: Interlocking landscaping planking wherein the opposite edges of each interlocking plank has a tongue and groove of special shape and relative dimensions to permit maximum flexibility in assembling curved landscaping arrangements consisting of multiple numbers of the planks joined side by side. The novel trapezoid or circular shaped tongue is centered vertically is one edge of each interlocking plank, its base indented slightly from the front and back surfaces of the plank to permit and to limit the lateral movement of the plank. The exterior surfaces of the tongue slope or curve inwardly, tapering to a flat apex. The novel trapezoid or circular shaped groove complements the novel trapezoid or circular shaped tongue, but spaced slightly therefrom and is centered vertically in the opposite edge of the plank, its mouth indented slightly from the front and back surfaces of the plank to permit and to limit the lateral movement of the plank.