This experiment was conducted to study the influence of different potash doses i.e., 0, 25, 50, 75 and 100 kg ha(-1) applied to onion cultivar Swat-1. The experimental results indicated that the significant maximum plant height, leaves plant(-1), medium size bulbs, large size bulbs, yield and bulb firmness, dry matter, pungent bulbs and TSS of bulbs were recorded with onion crop treated with 75 and 100 kg potash ha(-1). Sulphate of potash (SOP) fertilizer significantly produced tallest plant, firmed bulbs, dry matter, pungent bulbs, TSS of bulbs, small and medium size bulbs, as compared to muriate of potash fertilizer (MOP). There was about 76 days difference of post harvest life between cold stored and room stored bulbs. The minimum disease incidents, bulb sprouting at room temperature, bulb sprouting in cold store were recorded in 100, 75 and 50 kg K2O ha(-1). The significantly highest disease incidents, large size bulbs, bulbs moisture, bulbs sprouting at room temperature, bulbs sprouting in cold store, weight loss at room temperature and weight loss in cold store were recorded with MOP. The minimum small bulbs, moisture of bulbs, bulbs sprouting at room temperature, bulbs sprouting in cold store, weight loss at room temperature, and weight loss in cold store were produced by 100 kg K2O ha(-1). The behavior of the onions regarding weight loss and sprouting in both conditions were quite similar. The mean loss of weight in bulbs stored at room temperature was 47.7 %, while in cold-stored bulbs was 22.4 %. Similarly sprouting in bulbs stored at room temperature was 18.7 %, while in cold-stored bulbs was 6.6 %. It was noted that with increase of potash dozes in both sources of Potash (SOP or MOP) the decrease in weight loss and sprouting was observed. The weight loss and sprouting in SOP treated plots were lower as compared to muriate of potash.