The major causes of vase life reduction in cut flowers are the microbial proliferation in vase solution and consequently vascular occlusion preventing water uptakes. In order to control microbial proliferation efficiently, silver nanoparticles (Ag-NPs) are used as an enhancer to assess leaf extracts of Psidium guajava and Andrographis paniculata to alleviate xylem blockage in cut Mokara Red orchid flowers. The basal stem of each flower was re-cut and then pulsed with 0, 5 and 10 mg/L Ag-NPs for 24 h. The floral preservative solutions are comprised of control (125 mg/L 8-hydroxyquinoline citrate, 8-HQC) and double combination leaf extracts (DCLE) of P. guajava and A. paniculata, each at 15 mg/L. The preservative solutions of DCLE with 5 mg/L Ag-NPs had higher rates of solution uptake and trace amounts of bacterial suspension, which were responsible for increasing the vase life of cut Mokara Red Orchid flowers for 15.49 ± 0.15 days, compared to the 8-HQC control treatment 8.73 ± 0.16 days. Therefore, leaf extracts of P. guajava and A. paniculata have the potential as a biocide to minimize microbial populations and prolong the vase life of cut flowers. However, the potential activities of specific antimicrobial compounds to extend the vase life need to be tested.