We focused on the Cs uptake capacities of ornamental flowers. Ornamentals have the advantage of beautifying contaminated environments, and this may have therapeutic effects for individuals, especially in disaster areas. Furthermore, the use of ornamental plants will reduce the risk of pollutants entering the food chain. We hypothesized a strong correlation between high aboveground biomass and high Cs uptake in plants. We assessed the potential of 10 ornamental plant species for remediation of ¹³³Cesium in hydroponic solutions. Sunflower, rapeseed, and cosmos took up larger amounts of ¹³³Cs and showed better growth rates than the other 7 species. When these 3 species were exposed to 3 different concentrations of ¹³³Cs (0.5, 2, and 5 mg/L CsCl), more than 48% of the ¹³³Cs was remediated after 7 days in each case. The highest remediation rate was 67%, by sunflowers grown in 5 mg/L CsCl. Among the 3 species, shoot and root dry weights were highest in sunflower and lowest in cosmos. The rate of ¹³³Cs uptake was strongly correlated with aboveground plant biomass. The ¹³³Cs concentration did not affect plant growth rates in any of the three species.