In order to investigate the response of saffron to rate and time of application and two kinds of potassium (K) fertilizers, a factorial experiment was conducted with three factors, including the amount of potassium (0, 20.75, 41.5, 65.25, 83 and 103.75 kg K.ha^-1); time of application (annual application of K, and application of cumulative potassium needed for 4 years in the first year; these plots received 415, 332, 249, 166, 83, 0 Kg K.ha^-1,respectively in the first year and at other three years not received any K fertilizer); and sources of potassium (K₂SO₄ and KCl) with three replications in a randomized complete block design in Gonabad agriculture and natural resource research station for 4 years. Results of the first year were not analyzed, because these results not related to fertilizer treatments.Results showed that effect of potassium rate on saffron dry stigma was significant (P<0.05) and the highest dry stigma yield was obtained from application of 20.75 Kg K.ha^-1.Application time of K fertilizer had a significant effect on saffron dry stigma yield and application of fertilizer each year increased saffron dry stigma yield significantly (P<0.05) in compared to application of all fertilizer at the first year. Effects of sources of K on dry stigma yield of saffron was significant (P<0.05) and application of K in the form of K₂SO₄ increased dry stigma yield in compared to muriate of KCl treatment.