This research was performed to evaluate the effects of foliar application of nano-silicon (NSi), as a quasi-essential element, on yield, flower quality, vase life and infestation percentage of gerbera by greenhouse whitefly. Treatments were preharvest foliar application of different levels of NSi (0, 50 and100 mg/L) on gerbera 'Stanza' in a soilless system (to eliminate the effects of soil's Si) as a completely randomized design with three replications. Based on the results, activity of antioxidant enzymes including catalase and peroxidase and also flower quality such as flower diameter, stem height and longevity were significantly affected by NSi. Accordingly, NSi at 100 mg/L concentration showed the highest effect, compared with control (without NSi). However, yield or number of harvested flowers per plant were not affected significantly by NSi treatments. Also, whitefly infestation of isolated pots under NSi treatments showed less contamination percentage to whitefly egg, nymph, pupa and adult by 89, 99, 98 and 96%, respectively, as compared to control. Based on the significant and positive effects of NSi on flower quality and also whitefly control, further experiments could be recommended for comparison of NSi with other Si sources and chemical pesticides, and possible replacement of chemical fertilizers with Si-based fertilizers, particularly under soilless conditions.