Herein, we applied DNA Barcoding for the genetic characterization of Sideritis syriaca subsp. syriaca (Lamiaceae; threatened local Cretan endemic plant), using seven molecular markers of cpDNA. Five fertilization schemes were evaluated comparatively in a pilot cultivation in Crete. Chemical fertilizers (ChF), integrated nutrient management fertilizers (INM) and two biostimulants were utilized (foliar and soil application). Plant growth, leaf chlorophyll fluorescence and colour were assessed, and leaf content of chlorophyll, key antioxidants (carotenoids, flavonoids, phenols), and minerals were evaluat-ed. Fertilization regime did not affect leaf colour but induced distinct differences in leaf shape altering quality characteristics. INM-foliar and ChF-soil application promoted yield, without affecting tissue water content or biomass partitioning to inflorescences. ChF-foliar application was the most stimulato-ry treatment for enhanced antioxidant compound content, while INM-biostimulant was the least effec-tive one. In conclusion, adverse fertilization options appear as optimal when considering yield or anti-oxidant compound content. New DNA sequence datasets for the plastid regions of petB/petD, rpoC1, psbK-psbI and atpF/atpH have been deposited in the GenBank for S. syriaca subsp. syriaca while the mo-lecular markers rbcL, trnL/trnF, psbA/trnH were compared to those of another 15 Sideritis species re-trieved from the GenBank, constructing a phylogenetic tree to show their genetic relatedness.