The endogenous pool of phytoregulators in plant tissues supplied with microbial secondary metabolites may be crucial for the development of winter wheat seedlings during cool springs. Phytohormones may be synthesized by psychrotrophic microorganisms in lower temperatures occurring in temperate climate. Two fungal isolates from the Spitzbergen soils after the microscopic observations and ITS region molecular characterization were identified as Mortierella antarctica (MA DEM 7) and Mortierella verticillata (MV DEM32). To study the synthesis of indoleacetic acid (IAA) and gibberellic acid (GA) Mortierella strains were grown on media supplemented with precursors of phytohormones (tryptophan or methionine) at 9, 15 and 20 °C for 9 days. The highest amount of IAA synthesis was observed in MV DEM 32 9-day culture at 15 °C with 1.5 mM of tryptophan. At the same temperature the significant promoting effect (about 40% root and shoot fresh weight) of this strain on seedlings was observed. However, only MA DEM 7 had the ACC-deaminase activity with the highest efficiency in 9 °C and at this temperature synthesized IAA without tryptophan also at the same conditions the strain confirmed the strong promoting effect (about 40% root and 24% shoot fresh weight) on seedlings. Both strains synthesized GA in all tested terms and temperatures. Tested Mortierella strains had some important traits to consider them as microbial biofertilizers component improving plant growth in difficult temperate climate.