What stimuli will cause a mum plant to bloom?

Answer 1

Most chrysanthemums are obligate photoperiodic plants. That means that they are stimulated to bloom only by the length of daily darkness, which is known as the photoperiod. Most chrysanthemums are what is called 'short day' plants, although it might be more accurate to call them 'long night' plants. They bloom only when the daily nighttime photoperiod lengthens to a critical number of minutes. Preparation for flowering is initiated in periods of shorter nights (like in summer), when the buds that will eventually become flowers are created. The buds then lay dormant until the photoperiod lengthens to a critical point; the dormant buds awaken, grow and open to form the plant's blooms. To cause a mum to bloom out of season, you need to provide it with the night length required to stimulate flowering. It can be kickstarted in the summer by covering the plant at the beginning or the end of the day for several hours. This effectively increases the nighttime for the plant and can initiate blooming. In greenhouses, horticulturists can force photoperiodic plants to bloom at any time of the year by artificially controlling the length of light and darkness. This allows us to have mums in the spring and poinsettias in the winter.

Answer 2

Mums fall under a group of plants known as photoperiodic plants. These are plants whose development and growth depend on the length of day and night. With this in mind, it is worth pointing out that they will naturally blossom better during period when nights are longer. The only stimulus needed is longer nights.