The aim of this study was to determine the effects of hydrophilic polymers (hydrogels) and growth mediums on survive and growth of in vitro plantlets of winter squash and pumpkin during acclimatization. AAm EDTA JEL4, VPITA JEL4 and PCrA 0.18JEL3 were used with eight different growth mediums. The plantlets were propagated by in vitro embryo culture in solid E20A medium via irradiated pollen technique. Plantlets were transplanted to: (1) soil (2) soil with polymers (3) sand (4) sand with polymers (5) perlite (6) perlite with polymers (7) peat moss (8) peat moss with polymers. Growth mediums with polymers increased rate of survival and growth of in vitro plantlets of winter squash and pumpkin during acclimatization. Transplanted plantlets were survived in growth mediums with polymers range from 1.2 to 3.3 times more than controls.