Slippery elm trees grow in damp forest in areas across the United States and in portions of Canada. For hundreds of years, the bark of this tree has been used for soothing coughs and sore throats and for treating urinary tract infections. Native Americans would also create a balm from the bark and use it to treat open wounds. You must harvest slippery elm bark correctly, or the tree may contract disease. Harvest slippery elm bark before April or after June.
Use a sharp knife to slice away the bark from the main trunk of the tree. Cut deep enough into the tree so that you see the green layer that is somewhat slimy to the touch. Then begin peeling away the bark, down the tree's trunk.
Use scissors to cut up the strips of bark into small, square pieces.
Place the cut pieces of bark onto an old window screen or a piece of wire mesh for approximately two weeks in a cool, dry location. Allow it to dry until it is hard and brittle to the touch.
Place the pieces of dried bark into labeled, airtight storage containers and store in a cool, dark place.