Provided is a method of manufacturing wind turbine rotor blades, wherein each rotor blade includes an inboard section and an outboard section, and wherein an inboard blade section including a root end and a transition region is manufactured using a first casting process; and an outboard blade section including an airfoil region is manufactured using a second casting process, which second casting process is different from the first casting process. The invention further describes a wind turbine rotor blade manufactured using such a method.