To improve the propagation of Japanese cedar (Cryptomeria japonica D. Don), we investigated the effects of apical and basal temperatures during a water soaking treatment on the adventitious root formation of 70-mm long shoot tip cuttings which have an apical bud. The basal portion of the cuttings was soaked for 28 days in water with temperatures ranging from 10 to 35 A degrees C, at an air temperature of 5 or 10 A degrees C. Control cuttings were soaked in water at 25 A degrees C, with an air temperature of 25 A degrees C. Treated cuttings were then planted in vermiculite rooting medium and grown at an air temperature of 25 A degrees C for 35 days. Adventitious roots initiated earlier and developed more in the cuttings treated with apical temperatures of 5 or 10 A degrees C and basal temperatures of 20-30 A degrees C than in the control cuttings. The rooting percentage was greatest (93 %) in the cuttings treated with a 10/25 A degrees C apical/basal temperature, whereas few control cuttings rooted (13 %). This suggests that the temperature gradient created by warming the basal portion of the cuttings while cooling their apical end stimulates adventitious root formation. When we tested seasonal variation of rootability at 10/25 A degrees C, the rooting percentage increased from early autumn to winter, and decreased from winter to summer. The soluble sugar contents did not directly affect the formation of adventitious roots in the present study.