Experiments to study leaf surface formation in non-traditional forage crops for forage productivity were conducted in the permafrost zone on permafrost floodplain soils of Yakutia from 2023 to 2025. The objective of the study was to establish the characteristics of leaf surface formation in non-traditional forage crops for forage productivity in the permafrost soils of the Republic of Sakha (Yakutia). The objects of study were non-traditional forage crops: Altaisky 23 mogar, Stapayz paiza, Galiya sweet sorghum, Gvardeets sorghum-sudangrass hybrid, and Barnaulskoye 98 millet. Sowing was carried out in three terms: the first ten days of June (02.06, 04.06, 06.06), the second ten days of June (12.06, 14.06, 16.06) and the third ten days of June (22.06, 24.06, 26.06). The accounting area of the experimental plots was 25 m2, fourfold replication. The placement of variants was randomized. The sowing method was row with an inter-row spacing of 30 cm. It was found that, for all sowing terms, the studied crops developed slowly in the cryolithozone conditions, Stapayz paisa and Galia sweet sorghum reached the booting phase in autumn, the sorghum-sudangrass hybrid Gvardeets – the beginning of heading phase, Mogar Altayskiy 23 and Barnaulskoye 98 millet – the flowering phase of plants. The highest leaf area values were noted in the second sowing period for the crops of Barnaulskoye 98 millet (125.8 cm2/plant), Galiya sugar sorghum (125.4 cm2/plant) and the sorghum-sudak hybrid Gvardeets (140.0 cm2/plant). The maximum leaf area index (3.4 and 3.1) and high photosynthetic potential (2230.0 and 1918.7 thousand m2 x days/ha) stimulated the highest yield of green mass in Stapayz paisa and Barnaulskoye 98 millet crops – 24.6 t/ha and 27.5 t/ha, respectively. The grass stands of Stapayz paiza and Barnaulskoe 98 millet in the second sowing period (2nd ten-day period of June) synthesize an average of 2.62 and 2.33 g (m2 x days) per day during the growing season.