A perennial plant Miscanthus x giganteus has found its habitat and multiple applications in Europe, despite the fact that it originates from Asia. This study presents the potential use of this plant in new lightweight concrete materials so-called bio-concretes. The above-ground part of the plant was harvested, dried, crushed, and mixed with binders in different proportions. After casting and drying, the samples were characterized physical and mechanical properties. The results have shown that the sample with a higher content of binders while smaller miscanthus granulation and casted in molds under higher pressure exhibited the highest values of the compressive strength and density. In specific, the density was in the order of magnitude of that reported for other types of lightweight concrete with organic fillers, such as sawdust-based concrete ("Durisol"), which further justifies the use of miscanthus for these purposes.