The experiment was carried out in the Jiman region, which is approximately 15 km north east of Kirkuk Governorate, at degrees 35, -29, 134 north and 45, -31, 164 east and at an altitude of 559 m from sea level during the agricultural season (2019/2020) To study the effect of Foliar Spray of amino acid tryptophan and two cutting dates on some physiological traits, oil yield and specific qualities of lemon grass Cymbopogon citratus L. By designing the randomes Block design (RCBD), with Split-Plots cut system was combined with three replicates. Four concentrations of tryptophan amino acid were used (0, 150, 250, 350) mg. L -1 , since the plant was mowed during the first data in 1/6/2019 and the second on 1/8/2019, The averages were chosen according to the least significant difference test (L.S.D) to compare the arithmetic mean at the 5% probability level, and the results indicated that the date of the second Cutting date of lemon grass in physiological traits and the active substance exceeded the first date in these traits. As a result of the fact that the plants that were stuffed in the second date took their opportunity to form a strong root system that has the ability to absorb and quickly compensate the foodstuffs and convert them to the vegetative group in addition to the appropriate environmental conditions during their growth period, which was reflected in physiological characteristics and the active substance There is a steady increase in physiological traits and active substance by increasing the concentrations of the amino acid tryptophan sprinkled on lemon valerian plants due to the vital role that this acid plays in the internal physiological processes and appropriate environmental conditions for the cultivated plants. And that the increase in the concentrations of the amino acid tryptophan with plants for the second time reflected on improving the physiological characteristics and the active substance of the lemon valerian plant as a result of the compatibility of the growth of these plants with the increase in the concentrations of the amino acid of tryptophan favorable environmental conditions reflected on the plant.