Plastic preforms are introduced into a blow mold and are expanded by applying a flowable medium thereto, which is introduced into the internal space of the plastic preforms, wherein the blow mold includes at least two lateral parts which form a cavity during the expansion of the plastic preforms, within which the plastic containers are expanded. The lateral parts are respectively provided on lateral part carriers that are moved relative to each other for opening and closing the blow mold. At least one arrangement of a lateral part carrier and the lateral part provided thereon has an expansion element that can have a gaseous medium applied thereto. The expansion element ensures, when the gaseous medium is applied thereto, that one lateral part is moved towards the other lateral part. During the expansion of the plastic preforms, at least two different pressure levels are applied.