We evaluated the use of wild Phragmites australis as a biogas feedstock along with two perennial grass crops: Miscanthus x giganteus and Panicum virgatum. July biomass yields for P. australis were not statistically different than those of M x giganteus and were greater than those of P. virgatum, at 1.85 ±0.16, 1.28 ±0.15, and 0.49 ±0.06 kg dry matter (DM) m-2, respectively. The methane production potential of July-harvested P. australis was lower than M x giganteus, at 172.4 ±15.3 and 229.8 ±15.2 normalized liters CH4 kg-1 volatile solids, respectively. Findings from a secondary study showed that grass seeds were unable to survive long durations of anaerobic digestion. Seed viability of P. australis, P. virgatum, Phalaris arundinacea, and Solanum lycopersicum was reduced by 95% (LT95) after 29, 52, 98, and 105 hours of commercial-scale anaerobic digestion, respectively, whereas typical anaerobic digesters have operating times ranging from 240 to 1,480 hours.