This document was developed to provide a method for verifying that hexavalent chromium (CrVI) is not present in plant biostimulants in a concentration that exceeds the respective limits outlined in the EU Regulation on Fertilising Products [1]. This document is applicable to all types of plant biostimulants (solid and liquid) used in agriculture. The method described is suitable to quantify the chromium(VI) content in plant biostimulants down to 2 mg/kg. The results obtained from this method are strictly dependent on the extraction conditions. Results obtained by using other extraction procedures (extraction solution, pH, extraction time, etc.) are not comparable with the results produced by the procedure described in this document. Therefore, this document is highly recommended to quantify the chromium(VI) content in blends of fertilizing products containing plant biostimulants, independently of the percentage of the different parts forming the blend.