Secondary metabolites produced by different plants might inhibit or stimulate the growth and development of other plants present in its vicinity, this kind of interaction among plants termed as allelopathy. Lemon (Citrus limon) peels, flowers, and leaves were chosen for test extract preparation to check the seed germination and seedling growth of lettuce (Lactuca sativa L.) and cabbage (Brassica oleracea L. var. capitata L. f. alba D C.) and to observe their allelopathic potential. The experiment was conducted in sterilized Petri dish; germination of seeds was observed for ten days and the shoot length, root length and number of germinated seeds was evaluated. The effects of different concentrations of aqueous extract were compared to distilled water (control). The results showed maximum seed germination in control whereas all the test extracts showed very low germination percentage except lemon flower extract on cabbage seeds showing 80% seed germination. Root and shoot lengths were also reduced in all the test extracts except lemon flower extract against cabbage seeds which showed stimulated shoot growth. It may be concluded that lemon plant produces allelotoxins that can inhibit the growth of other crops in its vicinity. Although lemon flower extract showed the stimulatory effect on cabbage seeds, the detailed confirmatory study is necessary.