The objective of the research was to determine the effect of herbicides and herbicides combined with biostimulants on the leaf greenness index SPAD and selected potato characteristics, i.e. plant height, yield of large tubers and the vitamin C content. A three-year experiment was conducted to examine the following factors: factor I – three potato cultivars: Bartek, Gawin, Honorata; factor II – five methods of an application of herbicides and biostimulants: 1. control unit without chemical control, 2. the Harrier 295 ZC herbicide (linuron + clomazone), 3. the Harrier 295 ZC herbicide (linuron + clomazone) and the Kelpak SL biostimulant (Ecklonia maxima), 4. the Sencor 70 WG herbicide (metribuzin), 5. the Sencor 70 WG herbicide (metribuzin) and the Asahi SL biostimulant (sodium para-nitrophenol, sodium ortho-nitrophenol, sodium 5-nitroguaiacol). The cultivars investigated in the experiment significantly affected the leaf greenness index SPAD, plant height, yield of large tubers and the vitamin C content. The herbicides and biostimulants enhanced the values of the examined potato characteristics. Linear correlation coefficients confirm a strong, significant, positive correlation between the SPAD index and plant height, yield of large tubers and vitamin C content.