The study objective was to assess the allelopathic impact of the cut aboveground vegetative shoots of the selected lawn cultivars of L. perenne on the decorative value and species composition of the sward, including the share of dicotyledons. The studies were conducted in field conditions. The following indicators of the allelopathic impact of L. perenne were chosen: the share of the sown cultivars and dicotyledons in the lawn sward, general aspect, sward density and overwinter survival in object A, where the cut biomass was left, and in control object B, from which the biomass was removed immediately after cutting. The biomass of ‘Nira’ and ‘Stadion’ cultivars, cut and left on the lawn surface, exhibited auto-allelopathic properties by reducing their own share in the sward. The share of dicotyledons in the sward was reduced to the largest extent in the treatment where the cut biomass of ‘Nira’ cultivar was left. Only the ‘Stadion’ cultivar had a significantly lower sward density and a poorer general aspect of the sward in objects where the cut biomass was left in comparison with the objects where the cut biomass was removed. All the cultivars under study had better overwinter survival results in the objects where the cut biomass was left on the lawn surface.