Out of the 25 microorganisms commonly occuring in carnation (Dianthus caryophyllus L. ‘Improved White Sim’) vase solutions, 3 greatly reduced carnation vase life when added individually to vase solutions. Some of these microorganisms also reduced the vase life of roses (Rose hybrida ‘Cara Mia’), chrysanthemums (Chrysanthemum × morifloium Ramat. ‘May Shoesmith’) and other cultivars of carnation (‘Improved Red Sim’ and ‘Improved Pink Sim’). The microorganisms that reduced flower vase life were tentatively identified as a yeast, a fluorescent pseudomonad and a nonfluorescent pseudomonad. A 10-fold reduction in the initial inoculum level affected neither the final microbial concentrations nor the vase life of the test flowers. The effects of the different microbes were not correlated with their effects on solution pH.