A method of manufacturing a root section of a rotor blade of a wind turbine is disclosed. The method includes assembling a plurality of supporting rods with an interface section to a hub interface of the wind turbine in an essentially circular shape such that there are gaps between the supporting rods; arranging first fibers in the gaps which first fibers are physically and/or chemically compatible with an injection material; placing a first molding tool along an outer surface of the circular shape and a second molding tool along an inner surface of the circular shape, treating the injection material so that it bonds with the first fibers. The invention also concerns a supporting rod holding arrangement for such purpose and a root section of a rotor blade manufactured by such method.