The investigation of introduced herbaceous plant species, created new varieties and develop technologies of their cultivation in order to obtain the maximum yield of technological raw materials for further processing into divers types of products is an important object. We investigated some agro-biological peculiarities, biochemical composition of the perennial   herbaceous plant: giant knotweed Polygonum sachalinense cv. ꞌGigantꞌ and cup plant Silphium perfoliatum L. cv. ꞌVitalꞌ, and evaluating possibility to use biomass as fodder for animals and feedstock for bio methane production. It has been determined that in the 3-rd year of vegetation the studied species have an accelerated growth and development rate; the green mass yield varied from 12.3 kg/ m2(cv. ꞌGigantꞌ) to 12.5 kg/ m2 (cv. ꞌVitalꞌ); the calculated fodder productivity  reached 22 t/ha nutritive units, digestible protein varied from 1170 kg/ha (cv. ꞌVitalꞌ) to 3700 kg/ha (cv. ꞌGigantꞌ); bio methane production potential 5833-6250  m3 /ha, exceeding substantially corn hybrid.