Cut rose (Rosa hybrida L.) cv. Rote Rose was treated with glucose, fructose or sucrose at 10 g L^-1 in combination with a commercial preparation of isothiazolinonic germicide (a mixture of 5-chloro-2- methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one; CMI/MI; Legend MK) at 0.25, 0.5 or 1 mL L^-1. To stabilize germicidal activity, the solution was acidified by the addition of citric acid to a final concentration at 30 mg L^-1. Of the sugars, glucose was the most effective in extending the vase life, followed by fructose. CMI/MI was most optimal at 0.5 mL L^-1. The addition of aluminum sulphate at 50 mg L^-1 to glucose plus CMI/MI considerably extended the vase life of cut roses more than glucose plus CMI/MI. Based on these results, a formulation comprising 10 g L^-1 glucose, 0.5 mL L^-1 CMI/MI, 30 mg L^-1 citric acid and 50 mg L^-1 aluminum sulphate was designated as GLCA and the effect of GLCA on the vase life of 8 cultivars was compared against 10 g L^-1 glucose plus 200 mg L^-1 8-hydroxyquinoline sulphate (HQS). Treatment with GLCA extended the vase life of all the tested cultivars more than glucose plus HQS. Hydraulic conductance of stem segments in the control ‘Rote Rose’ roses decreased rapidly after harvest, but those for GLCA and glucose plus HQS were maintained at near their initial levels. The extension of vase life in cut roses by the addition of GLCA is attributed to the supply of sugars and the suppression of vascular occlusion without toxicity to cut flowers.