Annuals are a wonderful, colorful, and integral part of the plant world. By definition, an annual is a plant flowers and dies in the same year or growing season. Some flowering plants are perennials in warm climates and annuals in colder climates such as the Calibrachoa plant. In gardening, most people think of an annual as a plant that grows, blooms, and dies in one growing season. Some perennials are treated as annuals because they cannot survive the winters in cold climates.