Meadow hay, Sida hermaphrodita (L.) Rusby and Silphium perfoliatum L. as potential non-wood raw materials for the pulp and paper industry

•Multidisciplinary evaluation of three novel perennial crops as feedstock for the pulp and paper industry.•Meadow hay blends generated higher tensile indices compared to the pure birch control.•Fibre lengths of 0.5 (meadow hay), 1.3 (Virginia mallow), and 0.9 mm (cup plant) were measured.•The fibre widths of cup plant and Virginia mallow are broader compared to hardwoods.•These promising raw materials will be valueable in cardboard production for sustainable packaging.