The paper describes two series of experiments with Chinese cabbage (Brassica chinensis L.). The authors studied the productivity of crops and distribution of dry matter and nitrate pool in plant tissues. Plants were grown in a non-circulating passive hydroponic installation under white and red LEDs in nutrient solutions with various nitrogen concentrations (nitrate -from 40 to 150 mg/l, ammonia -from 0 to 70 mg/l). The study found positive correlation between the accumulation of dry weight of plants and the nitrogen concentration in the nutrient solution in the range from 40 to 120 mg/l. It was established that with the selected lighting mode, the concentration of nitrate nitrogen in the solution should not exceed 70 mg /1. Partial replacement of an ammonium nitrate form of nitrogen allowed to reduce nitrate concentration in the shoots without any loss of their productivity.