Decorate cake. Place small amount of icing on 6 in. board; attach to top of cake.
Holding hands on both sides of cake boards (top and bottom), line up bottom edge of cake with dark green sugar and roll cake forward, keeping cake on bottom edge of dark green sugar as you roll. Once complete, pick up cake and re-roll sections not covered in sugar.
Place cake on surface; carefully remove top cake board.
Prepare decorating bag with remaining white icing. Cut ¼ in. off tip of bag. Pipe icing on top of cake. Carefully smooth using spatula. Top with remaining pink sanding sugar.
Using small amount of icing, attach candy seeds to pink section of cake.