A biostimulating composition based on tannins and/or their derivatives, for the treatment of cultivated plants and/or parts thereof, comprises a first component including tannins, in an amount between 0.1 and 40% by weight of the composition, and a second component substantially consisting of a solvent, which first and second components are mixed to form a solution or a dispersion of said tannins and/or their derivatives, suitable to be applied on plants by distribution by perfusion.