Abstract: The invention relates to a method and a device for blow-molding containers. A preform produced of a thermoplastic material is subjected to a thermal conditioning process along a transport path in the region of a heating section. The preform is then shaped in a blow mold by the effect of a blowing pressure to give the container. The preform is subjected to a temperature profile at least along part of its transport path in the region of the heating section, said temperature profile being generated by at least one tubular radiation heater. The temperature profile extends in a longitudinal direction of the preform. The radiation emitted by the radiation heater is emitted in different spatial directions with different intensities by a heating device positioning the radiation heater.