Despite the increasing rate of nanoparticles (NPS) production and their application in agriculture, few studies have focused on their effect on plant growth. So, the present research was conducted in laboratory and greenhouse conditions. First, superparamagnetic iron oxide nanoparticles (SPIONS) with a humic acid coating (Fe3O4/HA) were synthesized in laboratory conditions by the chemical coprecipitation method. The effectiveness of the synthesized nanoparticles in vegetative growth and nutrients uptake of CHRYSANTHEMUM cut flower (CHRYSANTHEMUM morifolium) were evaluated in greenhouse conditions with four replications in a completely randomized design. The treatments consisted of 10, 20 and 40 mg/L of pure Fe from the source of Fe3O4/HA NPS and 1. 4 mg/L of pure Fe from two sources of iron chelates which contained Fe-EDTA(Fe-Ethylenediaminetetraaceticacid) and Fe-EDDHA [Fe-ethylenediaminedi(O-hydroxy phenylaceticacid)] were considered as control treatments in the open hydroponic cultivation system. The results of the laboratory experiment indicated that the synthesis of Fe3O4/HA by the chemical coprecipitation method led to the production of nanoparticles with an average diameter of 8. 38 nm and superparamagnetic properties. The greenhouse experiment demonstrated that the application of Fe3O4/HA significantly increased Fe uptake, chlorophyll and vegetative growth of the plants versus the control treatments. The highest rates of Fe, N, P, K, Ca, Mg, Mn, and B uptake were observed at the NP rate of 20 mg/L. The branch number per plant, stem height, and total dry weight of the plants were significantly increased by 25, 38, and 39. 5% versus the treatment of Fe-EDTA and by 50, 36, and 48% versus the treatment of Fe-EDDHA, respectively. It is concluded that magnetite NPs with a humic acid coating resolved Fe deficiency and increased CHRYSANTHEMUM growth.