The article presents the results of photobiological studies aimed at determining the preferred requirements for the spectrum of combined spectrum LED phytoradiators for the light culture of cucumber plants, variety Liliput F1. The studies were conducted in the artificial climate laboratory of FSBEI HE N.P. Ogarev Moscow State University, using an experimental research hydroponic plant. The results are presented and the effect of the spectral compositions of phytoradiators based on LEDs on the growth and development of Liliput F1 cucumber plants is estimated. The studies (the first vegetation) made it possible to preliminarily identify the most favorable radiation spectrum, which provides the best biometric characteristics and productivity of plants of Liliput F1 cucumbers.