Two field experiments were carried out during the summer seasons of 2016 and 2017, in a private farm, at Wadi El-Natroon city, Behiera Governorate, Egypt, under open field conditions in sandy soil. The main objective was to investigate the effectiveness of foliar application of both salicylic acid and potassium silicate on summer squash (Cucumis pepo L. cv. Hollar Queen F1 hybrid) as feeding fertilizers and to overcome the heat stress or over heat of summer temperature (from march to June) during squash plantation (vegetative growth, yield and quality). Treatments were consisted of two factors (two independent variables) as foliar application, i.e.; three concentrations of salicylic acid (1, 2, 3 mM) or / and four concentrations of potassium silicate (4.25, 8.50, 17, 34 mM) in addition to control plants that's treated with distilled water. Both conducted experiments were in a randomized complete blocks design, with three replications. Each replicate included 20 treatments. All determined treatments were distributed randomly within each block. Squash plants were sprayed with the allocated or assigned treatments twice during the growing seasons, the first one at 25 days after planting (the fourth true leaf stage) and after one week later. The recommended cultural practices for commercial squash production were followed. The obtained results indicated, generally, that foliar application treatments of salicylic acid (SA) and potassium silicate (K2SiO3) alone or in combination to squash plants might be considered as an optimal treatment for the production of high yield and good quality of summer squash. Specifically, the treatment combination between 2 mM salicylic acid plus 8.5 mM potassium silicate might be considered as an optimal treatment to produce high yield and good quality of summer squash under the environmental conditions of Behiera Governorate and other similar regions.