Like any other textiles, pleats need a certain amount of caring. Depending on the fabric and on environmental influences they should be regularly cleaned, so that you can enjoy them for many years. (Textilien)
Naturally, dust can settle on the transverse folds. Therefore it is recommended to remove it every few weeks with a duster or a soft brush. For that purpose the pleats should be completely unfolded and treated without pressure. You can also use a hoover, whereas the suction power should be as minimal as possible and the nozzle itself must not be dirty. (Falten)
A lot of fabrics can also be wiped damply, but only if it is stated in the care instructions by the manufacturer. Due to a usually increased humidity in bathrooms and kitchens compared to other rooms, here pleats should be used that are suited for moist rooms. These can then also be cleaned damply in order to remove dust more easily which occurred because of cooking vapour or condensed water. (Stoffe)
Some pleated fabrics can also be washed, therefore they must be taken down from the window. Best soak them in mild soapy water at 30 degrees in an appropriate container, e.g. the bathtub, for about 30 minutes before moving it a bit in the water to remove the softened dirt from the pleats. Afterwards fold the pleats to squeeze out the remaining dirt and soap water. Rinsing done once or twice under running water removes the final bits of the washing water. To get dry the pleats are first folded firmly to wring out most of the water. Let the pleats dry in this folded state, because that supports the preservation of the pleated structure. Only open it from time to time to check the degree of dryness and to loose dried up folds if necessary. (Plisseestoffe)
Always remember that all pleated fabrics consist of synthetic fibres, which need little care with their dirt-resistant surface. Water and dirt never enter the textures deeply, so that no pressure and no chemical cleaning agents are necessary. (synthetischen Fasern)