Two experiments were carried out in the experimental farm of Al-Kanater Research Station at ElQalyubia Governorate, during the two consecutive years of 2016/2017 and 2017/2018 to investigate the effect of potassium silicate foliar application on growth, productivity and some postharvest treatments on storability of garlic ((Allium sativum L.)" clone sids 40". In the field experiment, the treatments comprised of control(water spray),foliar application of potassium silicate at 4000, 6000 and 8000ppm and plants were sprayed at 30, 60 and 90 days after planting. In the storage experiment, cured bulbs were stored at room temperature conditions and subjected to sixteen postharvest treatments included the previous four treatments (the three potassium silicate levels and control). In addition, three spraying treatments of sodium silicate at 6000 ppm, chitosan at 200 ppm and calcium chloride at 3000 ppm both separately and their combinations with potassium silicate (three treatments in field) were done.   The results revealed that, the highest plant length, number of leaves, fresh, dry weight\plant, neck diameter, bulb diameter and chlorophyll content of garlic were achieved from foliar application of potassium silicate at the 4000ppm after 120 days from planting compared to the control. Foliar spray of potassium silicate at 4000 ppm recorded the highest total yield and bulb quality such as bulb diameter, bulb weight/plant, number of cloves, cloves weight, total soluble solids and dry matter of bulbs. Leaf K percentage significantly increased by spraying of potassium silicate at 6000ppm.Further, all potassium silicate treatments recorded higher silicon percentage over the control.  
Postharvest results showed that weight loss and shrinking percentages of the bulbs after 7 months of the storage were the least with the foliar application of potassium silicate at 8000ppm plus chitosan at 200ppm in storage followed by chitosan individually, potassium silicate at 8000 ppm and potassium silicate at 6000 ppm combined with calcium chloride as a postharvest treatment. However, the highest total soluble solids after 7 months of the storage was obtained from foliar spraying of potassium silicate at 4000 ppm combined with either sodium silicate or chitosan. Also, bulbs treated with foliar application of potassium silicate at 6000 or 8000 ppm combined with chitosan at 200 ppm, had the highest values of dry matter after 7 months from storage.  In general, foliar application of potassium silicate at 4000ppm was the superior treatment for enhancing plant growth, yield and quality. Also, foliar application of potassium silicate at 8000ppm and sprayed with chitosan at 200 ppm was the most effective for garlic storability seven months at the room temperature conditions.