A blade damping device for damping vibrations during standstill of a wind turbine blade, wherein the blade damping device is adapted to be detachably attached to the pressure side and/or the suction side of the airfoil region of the wind turbine blade, the blade damping device comprising a base plate adapted to conform to the exterior shape of the wind turbine blade when the blade damping device is attached to the wind turbine blade, and a spoiler protruding from the base plate to a spoiler height along a height direction and having a spoiler length along a length direction, the height direction being adapted to extend outwardly from the wind turbine blade, wherein the spoiler height is adapted to be at least 20% of a chord line located at two thirds of the blade length along the longitudinal axis from the root end of the wind turbine blade.