A device for encapsulating the roots of a tree seedling in a clay-like mud which comprises a flexible sheet secured at one edge to a base and having a blade extending along an opposite edge. A quantity of mud is placed on the sheet, the root system of the seedling is placed on the mud and then the sheet folded to bring the blade edge close to the opposite edge to fold the mud around the seedling. The blade is then slid along the sheet, away from the edge secured to the base, to form the mud into a generally cylindrical shape around the roots.