The Christmas cactus takes a longer duration with darkness before it can successfully set buds. The plant requires a 12-14 hours of continuous darkness during a night of approximately 6-8 weeks in the fall season. Blooming can be interrupted even by spending a couple of seconds in the light of artificial sources. The darkness of the room or the covering of the plant during the night is helpful to make the conditions in the plant similar to the natural conditions. After the formation of the buds, revert to regular light to have regular and bright flowers. Know more about How To Care For Christmas Cactus