Flowering in Chrysanthemum Chrysanthemums are short day plants. There is information that suggests that for each cultivar that there exists a specific minimum number of leaves that must form before the plant can flower. If that number of leaves has not been reached, then the plant will not flower even under short day conditions. Initiation under short days . If enough leaves have been produced, the plant will initiate flowers but the speed at which the plant initiates is cultivar dependent.
Some cultivars initiate quickly while others are slower.
The way this can be determined is to count the leaves and bracts under the flower. If you know how many leaves were there at initiation then you can count how many are there at flowering the difference were those leaves produced after the beginning of short days. It must be noted that there will be a certain number of leaf primordia in the vegetative bud. That number should be pretty much constant. Short days should be consecutive for the first 21 to 28 days.