European regulation (Regulation (EU) 2019/1009) defines a biostimulant as a product that stimulates the plant's natural processes to improve nutrient use efficiency, tolerance to abiotic stress or harvest quality, regardless of its nutrient content.
A biostimulant is neither a fertiliser nor a plant protection product. Its main function is not to supply nutrients or to control pests or diseases. The effects claimed on the label must be substantiated, and it is worth reading them carefully before comparing products.
The most common families are seaweed extracts, amino acids, humic and fulvic acids, plant extracts, certain microorganisms and some inorganic substances. Composition and claimed effect vary widely from one product to another, so the category alone does not guarantee a result.
When do they make sense? Mainly in abiotic stress situations: transplanting, extreme temperatures, salinity or occasional drought. Always as a complement to balanced nutrition, never as a substitute. Without a prior diagnosis of the crop and the plot, it is difficult to know whether the product will add anything.
To choose well, check the label: claimed effect, dose, application timing and authorised crops. Ask for the technical documentation of the specific formulation and be wary of result promises not backed by trials.
General information. Product and dose selection requires crop diagnosis and documentation for the specific formulation.