To characterize the phytotoxic potential, a laboratory experiment was conducted by considering some prominent wasteland weeds like Parthenium hysterophorus, Croton bonplandianum, Cassia occidentalis, Cassia obtusifolia, Calotropis procera, and Tephrosia purpurea. Aqueous leachates of leaf and root of different concentrations (50 and 100%) were tested against seed germination and seedlings growth of wheat and barley, as test plants. High concentration (100%) of leaf leachates showed remarkable inhibition on seed germination, radicle and plumule length and decreased biomass respectively, closely followed by the 50% concentration of leaf leachates. Maximum inhibition (> 70.00%) was recorded in 100% concentration of P. hysterophorus, C. occidentalis and C. obtusifolia leaf leachates as compared to root leachates (< 65.00%) except P. hysterophorus and similar trend of inhibition in radicle, plumule length and biomass was recorded. Root leachates showed least inhibitory effects at 50% concentration whereas 100% root leachates were comparatively more effective than 50% leaf leachates. A statistically significant interaction between leachates, concentrations and plants (P < 0.001) was observed; hence a significant inhibition was seen at higher concentration of leaf leachates. Inhibition potential of considered weeds clearly indicates the presence of phytotoxic chemicals in their tissues that supports them in establishment, competing and replacement of surrounding flora.