In pot experiments with growing peppers (Capsicum annuum L. cv. ‘Delphin’) in a peat substrate the release of nitrogen, phosphorus and potassium from controlled-release fertilizer Osmocote Plus 10-11-18 (5-6M) was studied. The action of this fertilizer is expected for 5-6 months. It was shown that for the first 21 days of cultivation, the release of nitrogen (N-NH4 + N-NO3) from Osmocote Plus 10-11-18 (5-6M) was 71.1%, that of phosphorus – 98.9%, and of potassium – 44.0 to 100%. Excessive levels of nitrogen, phosphorus and potassium in the substrate, which exceeded the optimum levels for the peppers, were maintained for 77 days. Intensive release of nutrients from the fertilizer caused excessive salinity of the substrate, which appeared on the 21st day and rose up to the 77th day of cultivation. Salinity decreased at the final period of plant growing, however it still exceeded acceptable levels for the peppers. This study shows that release of nutrients from the controlled-release fertilizer Osmocote Plus 10-11-18 (5-6M) assumed for 5-6 months takes place from the 21st day and lasts till the 77th day of cultivation. Intense release of nutrients at the initial period of plant growth could result in disorders in development and yielding of plants.