Bioretention is a best management practice (BMP). In this research, pot prototypes filled with bioretention media were built to simulate the conditions of natural growth of three grasses: Panicum virgatum, Kentucky-31 and Bromus ciliatus. Synthetic runoff was applied. The results show average removals of Zn, Cu, Pb and Cd exceed 90% by the bioretention media and the fates of input metals are 87.5-96.9% captured in soil media, 0.5-3.3% accumulated in plants and 2.0-11.6% not captured by bioretention media. Based on field biomass yields and laboratory metal concentrations in plants, it appears possible and practical to achieve removals of Zn, Cu, Pb and Cd of 20% by Panicum virgatum, 15% by Kentucky-31 and 10% by Bromus ciliatus, espectively. If 20% of input metals are accumulated by plants, the lifetime of a bioretention cell will be extended by 1.25 times.