A field experiment was done in a private Orchard at Gedilah Village in Al-Mansoura city, Dakahlia Governorate, Egypt, throughout the two summer seasons of 2021 and 2022 under clay soil conditions. The purpose of the research was to study the effect of drip irrigation rates{80, 100 &120% of water requirements (WR)}, potassium silicate as a foliar spray(once and twice at the concentration of 2 g/l)and their combinations on some vegetative growth parameters; plant height (cm), leaves dry weight (g/plant), water use efficiency (WUE), NPK%, total chlorophyll (mg /g F.W.), essential oil percentage and  its major components percentages of French basil (Ocimum basilicum L.) plant.The obtained results cleared that watering French basil with the rate of 120% WR or/and potassium silicate at 2 g/l as a foliar application twice /cut each season produced the tallest plants, the highest values of N, P, K% and total chlorophyll. In comparison the rate of 100 % of WR + potassium silicate as a foliar application at the rate of 2g/l twice for each cut /season gave the heaviest leaves^, dry weight (g/ plant) and the highest values of essential oil percentage compared to the control and other treatments. Moreover, GC-MS analysis discovered that the major constituent of French basil volatile oil was Linalool, which increased under the treatment of 80% WR and sprayed twice of potassium silicate at the rate of 2g/l. The previous findings highlight the synergistic effect of potassium silicate in enhancing chlorophyll assimilation, increasing leaves^, dry weight, and essential oil production.