The experiment was conducted on sandy loam soil in the years 2000–2002. The effect of the foliar application of the following preparations was compared: Atonik (0.2%), Ekolist (0.2%), Bioalgeen S-90 (0.3%) and water extract from dry great nettle (deluted in water 1:10). Preparations were sprayed on plants 3 times: 20 May, 2nd and 19th June. All preparations had a positive effect on the growth and development of plants, resulting in a significant increase of the yield and active component content of partenolid. Out of the preparations used, the most effective were Atonik and extract from great nettle (yield increase by 63 and 54%).