An apparatus for transforming plastic preforms into containers may include at least one blow mould which forms a cavity, inside which the plastic preforms can be transformed into containers. The apparatus may include a pressure application device for applying a medium to the plastic preforms in order to expand the preforms against an inner wall of the blow mould delimiting the cavity. The apparatus may include a stretching rod for stretching the plastic preforms in the longitudinal direction. The apparatus may include a cleaning device for cleaning regions of the blow mould. The cleaning device may include at least one outlet opening for a cleaning medium for cleaning the blow mould, and this outlet opening is arranged at least at times inside the blow mould.