Hoisting systems are provided for mounting a hub (108) on top of a tower, the hub carrying a first and a second blade (103, 104) forming a bunny ears configuration, and a third blade (105). The system comprises a crane (100) for pulling up the hub to the top of the tower, and a blade support () for supporting the third blade at a supported blade portion. The system further comprises a hub-blade coupling device configured to assist in coupling a root portion of the third blade to a coupling portion of the hub. The hub-blade coupling device comprises a hub mount structure configured to be removably fixed to the hub, a blade mount structure configured to be removably fixed to the third blade, and a connector rotatably coupling the hub mount structure and the blade mount structure. Methods are provided of mounting a hub on top of a tower by using any of said systems.