Two cultivars of tulip (Tulipa gesneriana L.) were used to check the effect of trehalose-feeding on longevity of vase life. `Oxford' plants were grown from bulbs, and trehalose-fed cut flowers were compared with the intact plants grown in pots. `Pink Diamond' flowers were obtained commercially as cut flowers from the market, and trehalose-feeding was examined by using only flower parts. In both cultivars of plants, it was confirmed that trehalose-feeding enhanced longevity of the vase life significantly at room temperature. Additionally, mechanisms of prolonging the vase life with trehalose-fed flowers were studied by comparing the water status in the zone of elongation of tulip tepals when their growth rates were modified with different treatments. In the elongating region of tulip tepals, cell elongation rates were linearly correlated to sizes of the growth-induced water potential regardless of treatments. It was found that trehalose-feeding reduced the hydraulic conductance, resulting in a decrease in cell elongation rates. Also, trehalose helped to maintain turgor of tepal cells for longer periods. Furthermore, trehalose enhanced pigmentation in tepals, and thus, trehalose is believed to have had a role in altering the metabolism in elongating cells and in reducing hydraulic conductivity in membranes.