My U. longifolia typically puts up flower stalks in early spring and flowers throughout the summer, but this year it has started early. I've suspected that slightly warmer weather might be the flowering trigger, but this year has dispelled that theory, as it is the coldest it has been so far this winter. The plant is in a room in the house which has very little heating, just receiving ambient heat from the rest of the house, so temperatures in there are cool.