Biochar, a carbon rich product formed by the incomplete combustion of biomass, has been shown to improve soil quality and increase crop growth but has not been evaluated in tallgrass prairie ecosystems, even though fire has historically been an important ecological aspect of the prairie system. We assessed the response of a native perennial grass, Andropogon gerardii (big bluestem), and a non-native herbaceous perennial, Lespedeza cuneata (sericea) to biochar amendments in a series of experiments. Big bluestem plants were generally taller and produced more biomass when grown with biochar than without it. Sericea growth was either reduced or not affected by biochar amendments. Competition between big bluestem and sericea was asymmetrical; sericea reduced the growth of big bluestem but big bluestem had relatively little effect on thegrowth of sericea. Biochar did not increase big bluestem growth enough to change competitive outcomes between sericea and big bluestem. However, biochar increased the growth of big bluestem plants that were grown in soilthat previously contained sericea; biochar may improve big bluestem establishment in areas where sericea has been controlled. Our research suggests that biochar has the potential to increase the growth of big bluestem and may be a useful tool for prairie restoration.