Carnation (Dianthus caryophyllus L.) is one of the main floricultural crops in Japan and worldwide. The vase life of cut ornamental flowers, including carnations, is important in determining their quality and consumers' preference. To improve the vase life of carnation flowers, my group started a breeding research program in 1992 using conventional cross-breeding techniques. We repeatedly crossed and selected promising offspring with long vase life for seven generations, from 1992 to 2008. In 2005, we developed two cultivars, 'Miracle Rouge' and 'Miracle Symphony', with genetically determined long vase lives of 17.7 to 20.7 days (3.2 to 3.6 times that of 'White Sim') under standard conditions (23°C, 70% RH, 12-h photoperiod). Line 532-6 showed an ultra-long vase life averaging 27.8 to 32.7 days (4.6 to 5.4 times that of 'White Sim'). We evaluated changes in ethylene sensitivity with flower senescence simply and accurately using a time-lapse video recorder. In 2010, we selected line 806-46b with both ultra-long vase life (27.1 days, 4.4 times that of 'White Sim') and ethylene resistance. Analyses using six cultivars and 123 selected lines from the 1st to the 7th generations revealed that the long vase life was strongly associated with a decrease in ethylene production.