An experiment was carried out at Vegetable Experimental Farm, Division of Vegetable Science SKUAST-K, Shalimar Srinagar during kharif 2011 to find out the optimum dose and best time of potassium application for improving growth, yield and quality attributes of potato cv. Kufri Jyoti.The observations were recorded on growth parameters such as plant height, plant spread, No. of shoots plant-1, yield and yield related related parameters as number of tubers per plant, average tuber weight(gms),total yield (q ha-1) and quality parameters viz., T.S.S, protein content, vitamin C, specific gravity and dry matter. The results proved among various treatments, the plants supplied with 150 kg per hectare potassium irrespective of time of applications recorded maximum values of plant height (75.16 cms), plant spread(44.15 cm), no of shoots plant-1(9.36), number of tubers per plant (10.20), average tuber weight(gms) (65.162 ), total yield (301.59 q ha-1) and protein content (2.62%), specific gravity (1.14), dry matter (23.38%) and vitamin C (23.12 mg) except T.S.S (4.67%) where values were minimum at this level potassium application. However, results differed with time of application of potassium in case of same dose of potassium application.