Two field experiments were carried out at Ali Moubark Agric., Res. Station during two successive seasons 2007/2008and 2008/2009 on potato cv. Diamant to study the vegetative growth characters, tuber quality, tuber minerals content and total tuber yield as affected by the application methods of K-fertilizer (soil application, foliar application and soil + foliar application, either single and /or in combination with foliar application of zinc or manganese or boron) three times during plant growth i.e. at 45, 60 and 75 DAP.Almost all the parameters of the potato plants which received 50% soil application K-fertilizer + 50% foliar application significantly increased as compared with other application methods.On the other hand, most vegetative growth parameters were significantly increased by foliar spraying of potato plants with micronutrients and led to improve the tuber quality parameters i.e. all carbohydrate fractions, the protein of tuber, the tuber weight and total tuber yield as compared with the control.In general, application of K-fertilizer as 50% of the recommended rate used as soil application + 50 % of that added as foliar application in combination with foliar spray of micronutrients recorded maximum values of plant growth parameters, improved tuber quality characters and obtained highest tuber yield/fed. Therefore, this treatment could be recommended for raising potato yield and improving tuber quality and reducing the productive cost under similar conditions.