Psidium friedrichsthalianum (O. Berg) Nied. (Cas) is a guava species from Myrtaceae family whose fruits are very attractive for their organoleptic properties, its economic and nutritional importance and its use as rootstocks. One of the main problems for in vitro propagation of Cas is contamination, and silver nanoparticles (AgNPs), are the most useful in the treatment of plant tissues due to their microbicidal action. Thus, the microbicidal effect of Argovit™ AgNPs (suspension in water, with PVP 18.8 wt% and metallic silver 1.2 wt%, in spheroids form of 35 ± 15 nm, hydrodynamic diameter of 70 nm and zeta potential of − 15 mV) was evaluated either, through the disinfection of Cas shoot tips explants or by dispensing a liquid layer of AgNPs onto the semisolid culture medium during the in vitro establishment phase. The effect of Argovit™ silver nanoparticles in the multiplication rate and the foliar area of Cas was also evaluated. Application of AgNPs 50 mg/L directly to shoot tips during 5 min yielded a contamination rate of 40%, while culture medium sterilization with 5 mg/L of AgNPs as a permanent bilayer reduced shoot contamination rate to 50% compared to 80% for the controls. In addition, Argovit™ silver nanoparticles also enhanced foliar area by 560% (from 0.073 to 0.409 cm 2) and multiplication rate by 180% (from 1.286 to 2.286 shoots/explant). The study concluded that the best way for in vitro use of AgNPs on propagation of P. friedrichsthalianum, is as sterilization agent of the culture media because produce additional advantage of enhancing the leaf area and multiplication rate of the shoots.