Printing plates are prepared at installation positions on one of a plurality of plate cylinders disposed in a printing machine. A plurality of flat printing plates, which are provided for a printing process to be carried out by the printing machine itself, and which printing plates are themselves bendable, at least along their length, are provided at the outlet of a plate line which is spatially separated from the printing machine and which comprises at least one plate exposure device. Each of the printing plates is temporarily stored in a specific shelf of a mobile collection container that has a plurality of such shelves. The printing plates which are stored in the same mobile collection containers are prepared for installation positions of the same plate cylinder. Each shelf of each of the mobile collection containers storing one of the printing plates is selected based on the intended installation position of the respective printing plate on the respective plate cylinder using data that is provided by a control unit of a production planning system. The data is provided prior to the storing of the printing plates. The printing plates which are stored in the mobile collection container, and which are to be provided to the same plate cylinder, are conveyed to the printing machine in a pre-sorted storage condition.