Two field experiments were imposed during the winter seasons of 2012 and 2013 to study the main and interaction effects of spraying humic acid (0, 500, 1000 and 1500 ppm), Salicylic acid (0, 500 and 1000 ppm) and copper (0, 200 and 400 ppm) on vegetative growth and bulbs yield and its components of onion plants cv. Giza 20. The experiments were carried out in the Experimental Station Farm at Abeis, Faculty of Agriculture, Alexandria University. The main effect of spraying humic acid, salicylic acid and copper, irrespective of the concentration used, significantly, increased number of leaves plant^-1 and plant height relative to the untreated control. The highest concentration of humic acid, salicylic acid and copper, positively and significantly, increased marketable and total bulbs yield. The second order interaction of humic acid, salicylic acid and copper at the highest concentration was the most effective treatment which gave the best vegetative growth and highest total and marketable bulbs yield.