The research was conducted between 2014 and 2016 at the Agricultural Experimental Station of the University of Environmental and Life Sciences in Wrocław. In the experiment, Poa pratensis and Lolium perenne in pure stand and in mixtures were used as Factor A. Two substances that stimulate grass growth and development constituted Factor B. The first was a biostimulant produced from brown algae (Phaeophyceae), containing various essential chemical compounds including amino acids, vitamins, alginic acid, microelements, and other unexplored biologically active components. The other was water treated with low-pressure glow plasma (LPGP). The seeds were sown in well-mixed light, alluvial loamy sand soil. During three growing seasons, a 9-point scale was used to evaluate grass density, leaf fineness, susceptibility to disease, and lawn overwintering. The lawns were mown every 14 days at a height of 4 cm. The substances with a stimulating effect significantly affected lawn grass features, including turf density and overwintering. Additionally, the biostimulant and plasma water reduced the incidence of fungal diseases. Better transport of water in plants after its low-pressure glow plasma treatment may be due to the effect of its declustered structure, its higher oxygen concentration, and its better solubility of the biostimulant.