This investigation was conducted during the two growing successive winter seasons of 2014/2015 and 2015/2016 at the Experimental Farm of Sids Agricultural Research Station, ARC, Beni-Suef Governorate, Egypt to study the response of two bread wheat varieties (Sids 12 and Sids 13) and two durum wheat (Beni-Suef 5 and Beni-Suef 6) to potassium fertilization as soil application and/or foliar spraying. The treatments were: without potassium fertilization (K1), 24 kg K2O/feddan as soil application one time before planting (K2), 12 kg K2O/feddan as soil application before planting + 12 kg K2O/feddan as soil application added after two month later (K3), foliar spraying of 2% potassium sulphate one time (K4), foliar spraying of 2% potassium sulphate twice (K5), 12 kg K2O/feddan as soil application + foliar spraying of 2% potassium sulphate one time (K6) and 12 kg K2O/feddan as soil application + foliar spraying of 2% potassium sulphate twice (K7). The results indicated that Sids 12 variety gave the shortest days for heading and maturity stages and greatest number of spikes/m²and number of grains/spike, while Beni-Suef 5 variety possesed the highest values of plant height, 1000-grain weight, grain yield and straw yields as well as total N, P and K uptake. On the other hand, Sids 13 variety recorded the lowest values of plant height, 1000-grain weight, grain yield, straw yield and total NPK uptake, while Beni-Suef 6 gave the lowest number of spikes/m² and number of grains/spike. The highest values of number of days to heading or maturity stages were recorded for Beni-Suef 5 variety. Added K3 or K7 treatments exhibited the greatest period to heading and maturity stages. On the other hand, the wheat plants without potassium application exerted the lowest growth parameters, yield and its components as well as total NPK uptake. In general, Beni-Suef 5 variety when fertilized with K3 or K7 treatments produced the highest values of wheat growth, yield and its components