Abstract: The experiment was conducted at the Horticulture Farm of Bangladesh Agricultural University, Mymensingh during November, 2000 to August 2001 to determine optimum planting time on growth, yield and storage performance of onion. Three dates of planting viz., November 22, December 7 and 22 and, two storage conditions viz., inside sand and open on bamboo platform. The planting time had significant effect on growth, yield components, yield and also storage parameter studied. The November 22 planting produced the highest yield (25 t ha-1) by increasing leaf number per plant(11.73), bulb diameter (5.31cm), fresh weight of bulb(59.60g) and dry matter content of bulb(13.44%). In the three planting times, the rotting percentage was higher (15.51, 8.66 and 8.34 respectively) under inside sand storage. The highest weight loss (29.21%) and sprouting (1.98%) were obtained by November 22 planting with open storage on bamboo platform.