The objectives of this study are to evaluate the effects of a hydrophilic polymer (Superab A200) on the growth indices of an ornamental plant (Cupressus arizonica) under reduced irrigation regimes in the field and on the soil water retention curve in a laboratory. The Retc computer programme was used for obtaining optimum model parameters. Superab A200 in two levels, 4 and 6 g/kg, were mixed with two soil textures of clay and sandy loam, respectively. The results of the soil water retention model showed that, Superab A200 caused the residual water content ( qr) and saturated water content (qs) to increase. Air entry value (hb) was observed to decrease in the clay and increase in the sandy loam. The results of the statistical analysis showed that there is a significant difference between samples containing Superab A200 and without hydrophilic polymer (the control) and the levels of polymer application. Available water content increases 2.3 fold of the control at maximum, with hydrophilic polymers application of 6 g/kg in sandy loam soil. The field trials were conducted as a split plot on the random complete blocks design in which the main plot treatments were two irrigation regimes consisting 33% and 66% evapotranspiration (ETc) and two sub-plot treatments were soils containing 4 and 6 g/kg hydrogel, respectively. The control blocks had no hydrophilic polymer and irrigated with 100% ETc. The results indicated that plant height, shoot diameter and length of green, are the same in treatments containing 4 and 6 g/kg Superab A200 and receiving irrigation water 66% ETc with the control. Thus, application of 4 and 6 g/kg hydrophilic polymer reduced the required water to 1/3 of the control. Application of Superab A200 can result in significant reduction in the required irrigation frequency particularly for light soil texture. This is an important issue in arid and semi-arid regions of the world.