A water-retaining support for plant which exhibits a water-retaining ability comparable to that of a polyacrylic acid-type hydrogel substantially without causing the inhibition of root origination or inhibition of root elongation is obtained by using as a water-retaining support for plant comprising a hydrogel-forming polymer having a calcium ion absorption of less than 50 mg per 1g of the dry weight thereof and having a water absorption magnification in ion-exchange water (at room temperature; 25 DEG C) of 100 or more. When the above water-retaining support is used, a plant may be supplied with sufficient water without suffering from deficiency of calcium ion. <IMAGE>
