Newly transplanted New England asters (Sym- phyotrichum novae-angliae) get a blanket of cardboard before I add mulch to keep unwanted growth from starting.
Cut down ash tree trunks damaged by emerald ash borers form the outline of new planting beds that will next get covered in cardboard to smother any existing plants.
Cardboard cleared this southern side of my house before I started developing the native pink phlox.