The article reports influence of different environmental conditions on the productivity of Linum usitatissimum L. (flax or flaxseed) in Uzbekistan. Analyses of the plant productivity were carried out on the rainfed lands and in the conditions of the Tashkent Botanical Garden. Phenological studies revealed differences in various phases of the growing period. Morphometric parameters that determine yield of L. usitatissimum seeds under different conditions were determined. The seed yield per plant on average in the Botanical Garden was 79.4 ± 4.00, and at various regions in the rich lands such as Malguzar 76,8±4,33, Pishagar 74,2±4,54 and Khatyrchi district was 76,5±4,28. The results of the studies can be used by farms in cultivating L. usitatissimum in the Republic of Uzbekistan.