The allelopathic activity of cover crops, green manure, mulching plants, and weeds commonly found in tea plantations was evaluated employing laboratory bioassays, greenhouse experiments and field trials. The results of laboratory and greenhouse experiments concluded that the green manure plants, Gliricidia sepium, Erythrina lithosperma, Eupatorium inulifolium, Tithonia diversifolia, Artemisia vulgaris and mulching plants, Chrysopogon zizanioides, Tripsacum luxum and Pennisetum purpureum × Pennisetum americanum exhibited phytotoxicity against Lactuca sativa. According to the findings of the field tests, these plants significantly exhibited phytotoxicity toward weeds present at the experimental sites. In combination with integrated weed management, these plants could be utilized to manage weeds in sustainable agriculture.