Microbe producing natural herbicides are alternatives to the chemical herbicidal formulations. The effect of minerals and carbon sources were screened to select the best when combined and when apply singly during submerged fermentation. The effect of their phytotoxic metabolites was tested on Chromolaena odorata and Echinochola crus-galli. It was observed that the best combination between all the mineral was found in the combination containing manganese, zinc, bromine and iron. It gave the highest bio-herbicidal activities on the tested weeds when compared with the basal medium without any mineral amendment (P ? 0.05). The best carbon source screened was glucose while the best mineral screened was iron in term of showing activities on the tested weeds (P ? 0.05).