The integration of plant biostimulants use to improve the efficiency of crop production can contribute to increasing the agronomic efficiency. Through this study we aimed to investigate the cytogenetic effects of the Quantis biostimulant on the meristematic cells of Allium sativum (garlic), at different concentrations (1, 1.5 and 2.5%) for 8 and 24 h. The results obtained showed that, at 1 and 1.5% concentration, Quantis induced the increase of the mitotic division intensity in A. sativum cells, both during at 8 and 24 h of treatment, compared to the untreated control variant. This fact suggests that, at the respective concentrations, Quantis improves the growth and development processes of the plant. In contrast, at 2.5% concentration, the index of mitotic division decreased by 36.6% (at 8 h), respectively by 64.9% (at 24 h of treatment), compared to the control. Also, at 2.5% Quantis, some chromosomal aberrations and nuclear anomalies were recorded: sticky and laggards’ chromosomes, C-mitosis, micronucleus, nuclear bud and nuclear dissolution. These results suggest that when is used in high concentrations, Quantis induces some cytotoxic and genotoxic effects on A. sativum, which can disrupt the plant growth.