Biostimuatori su (ne-hranjive) tvari ili mikroorganizmi koji pospješuju procese hranidbe biljaka i doprinose smanjenju posljedica stresa uzrokovanog abiotičkim i biotičkim čimbenicima. Mogu biti mikrobni (korisne bakterije i gljive) i nemikrobni (huminske kiseline, aminokiseline, ekstrakti morskih algi, kitozan i anorganski biostimulansi). Različitim mehanizmima djelovanja biostimulatori potiču učinkovitije iskorištavanje hraniva, otpornost biljaka na stres i povoljno djeluju na kvalitativna svojstva biljaka. Uslijed restrikcija u primjeni sredstava za zaštitu bilja i gnojiva, kao dio alternativnih rješenja pojavljuju se biostimulatori. Biostimulants are (non-nutrient) substances or microorganisms that improve plant nutrition processes and help reduce the effects of stress caused by abiotic and biotic influences. They can be microbial (beneficial bacteria and fungi) and non-microbial (humic acids, amino acids, seaweed extracts, chitosan and inorganic biostimulants). Through their various mechanisms of action, biostimulants enhance the efficiency of nutrient utilization, the stress resistance of plants and have a positive effect on the qualitative characteristics of plants. Due to the limitation of applicable pesticides and fertilizers, biostimulants are also a part of the alternative solutions.