Slinging nettle (Urtica dioica L.) is a perennial plant which has been widely used in medicine, food, textile and cosmetic industries as well as in organic production. Whereas it is quality control of wild plant material difficult and expensive there is a need to introduce nettle in to agricultural production. Application of modern cultivation technology (floating hydropon) can eliminate mentioned problems. Higher yield and increased number of harvests in the period when the nettle is already dormant in the open field can be achieved. The experiment was laid out according to the randomized complete block scheme with three replications in unheated greenhouse. The effect of three sowing densities (0.2, 0.5 and 0.9 g m-2) and two substrates (perlite, vermiculite) on the stinging nettle yield and number of harvest were tested. Sowing was conducted in the first decade of September in 2012. During the nettle cultivation five harvests were realized: two in autumn (October 23, November 29) and three in spring period (March 15, April 16 and May 6). In autumn season plants grown in perlite had significantly more leaves and the nodes compared to those grown on vermiculite. Higher sowing density resulted in higher yield in autumn growing period (0.57 kg m-2) while in the spring higher yield was recorded in the lowest sowing density (1.01 kg m-2). Regardless sowing density an equal yield of stinging nettle was achieved in vermiculite (0.93 kg m-2) during autumn and in perlite (1.08 kg m-2) during spring period. All tested parameters were significantly affected by sowing density x substrate interaction during the nettle cultivation. In autumn period the combination of vermiculite x 0.5 g m-2 resulted with significantly highest yield (0.96 kg m-2) while in spring the highest yield (1.41 kg m ) was achieved by combination of perlite x 0.2 g m-2.