Mums can bloom for several weeks and up to two months. This depends on several environmental factors, such as where they are grown, when they are planted and the care they are given.
Mums grow well in plant hardiness zones 5 through 9. While they bloom in the fall, the flowers of the mum plant last longer if the plant is placed in the ground in the spring. Another factor that increases bloom length is the amount of fertilizer the plant receives during the spring and summer months. Overly wet and dry seasons can also affect the amount of time mums retain their petals.