The effect of foliar feeding with four biostimulants with active substances (Ecklonia maxima algae extract, titanium, humic substances, plant hormones: auxin and cytokinin) on the chlorophyll content and plant height of three Solanum tuberosum cultivars was investigated. A field experiment was carried out in 2015-2017 in eastern Poland in three growing seasons using the split-plot method. The cultivated varieties significantly differentiated the chlorophyll content (SPAD index) and plant height. The research showed the influence of varieties and many years of research on the height of potato plants. The biostimulants increased the value of the SPAD coefficient and the height of the potato plants.