What condition must be met for mums to set flower buds and bloom?

Mums, or chrysanthemums, are photoperiod-sensitive plants, meaning their flowering is influenced by the duration of light and darkness they receive. For these plants to set flower buds and subsequently bloom, they require long nights and short days. This condition typically occurs in the fall when the daylight hours decrease and the nights become longer.

When the nights exceed a certain length, it triggers the physiological processes in the plant that lead to bud formation. This response is an adaptation to synchronize their blooming with the changing seasons, which is crucial for their reproductive cycle. Thus, the condition of having long nights and shorter days is essential for the proper development of flowering in mums.