The chemical composition and efficiency of biogas production in the methane fermentation process of silages of wild and cultivated varieties of reed canary grass were compared. An attempt was made to answer the question on how the habitat and the way of utilization of plants affect chemical composition and biogas yield. Physicochemical properties such as dry matter, organic dry matter, protein, fat, crude fiber fraction, macro- and microelements content were considered. The anaerobic digestion process and FTIR analysis were also carried out. The results showed that the two varieties differ essentially in their physical and chemical properties. The cultivated variety was characterized by higher biogas yield (406 Ndm3 kg−1 VS) than the wild one (120 Ndm3 kg−1 VS). This was probably related to the chemical composition of plants, especially the high content of indigestible crude fiber fractions and ash. These components could reduce biogas quantity and quality.