Silver Fos — a plant growth regulator in the form of an aqueous solution, containing colloidal silver and polyhexamethylene biguanide hydrochloride. The preparation is used to increase the yield of cereal grain crops. The product is used in two forms: as a soil fertilizer and as a root fertilizer, at a dosage of 0.06 to 0.1 ml per kilogram of weight or 0.6 to 1.0 ml per 100 m² area. Applied once. Silver Fos is manufactured by the company PP "Charoit", located in Ukraine, Kyiv, Darnitskyi district, Kharkovskoye highway, building 144B. The preparation is registered under number 15859 and registered on 08.11.2023. The preparation is an aqueous solution containing colloidal silver at a concentration of 500 mg/l and polyhexamethylene biguanide hydrochloride — 100 mg/l. It ensures effective yield increase for crops by regulating plant growth, which is especially important for cereal grain crops.