Allium cepa (Onions) is one of the major vegetables that is consumed all over the world after tomatoes due to is active compounds but weeds infestation during growth phase are the major challenge faced by the farmers which result in a very poor growth and yield of this spice. In this study, the conventional hand weeding practices were compared with weedicide pendimethalin to control different weeds and the morphological characters such as; number, size, height, neck area and fresh weight of the onions bulbs planted at Department of Plant Science and Biotechnology, Botanical Garden, KSUSTA. Twelve (12) weeds of different family were found and identified from the experimental field namely; Urena lobata, Eragrostis tremula, Amaranthus viridis, Senna occidentalis, Cenchruse chintus,