Abstract: Experiments were conducted to determine the effects of Thidiazuron (TDZ) applied at preharvest stage under glasshouse conditions on Dianthus caryophyllus 'Lunetta'. Thidiazuron at 0, 1, 10, 100, and 1000 uM was applied as a foliar spray arranged in completely randomized design. Time to flowering was recorded, and relative stem length, total nitrogen and tissue water content were measured at harvest. Postharvest vase life, relative fresh weight changes, and solution uptake were also measured. TDZ treatments decreased relative stem length compared to the control (0 uM). TDZ treatment tended to decrease total nitrogen and water content of tissues slightly, but not significantly (P > 0.05). TDZ at 100 uM significantly increased the vase life of cut carnation flowers compared to the control. TDZ treated flowers tended to maintain higher relative fresh weight, with positive differences for the 100 uM TDZ treatment being apparent at day 5, 7 and 9 of vase life. Solution uptake was higher in TDZ treated flowers.