Abstract: Previously we have developed a method, which uses two criteria, ‘time to flower opening’ and ‘vase life’, for characterizing flower opening profiles in cut spray-type flowers of carnation. These two criteria were used to evaluate the activities of flower preservatives, which accelerate flower bud opening, resulting in shortening the time to flower opening, and delay senescence, resulting in extension of vase life. In the present study, we developed the third criterion ‘gross flower opening’ which characterizes the ability of flower buds to open. Using this criterion the activity of analogs of pyridinedicarboxylic acids was successfully evaluated in addition to the previously-reported evaluation of their activity of acceleration of flower bud opening and extension of vase life.