A tulip bulb is an amazing container: a swollen underground stem that stores food and energy. It contains a miniature plant with flower, leaf, and root parts, all ready to spring forth when conditions are right.
Tulips bloom in spring from early March to late May. Before they can bloom, the bulbs need a period of cold, so you should plant them in the fall. In the cold soil bulbs can grow big and develop strong roots, to turn into beauties in spring.