Cosmo flowers come in many varieties, but two of the most popular are Cosmos sulphureus and Cosmos bipinnatus. Cosmos bipinnatus bloom in a wide variety of pink cosmos and may also be known as Gloria Cosmos. These pretty garden flowers will rebloom each year, but are technically annuals.
Annual vs. Perennials
Annual flowers are those which only survive through one growing season. Perennials die back in the winter, but grow again the following spring from the same root structure.
Cosmos flowers, including pink cosmos, are classified as annual flowers, according to the Aggie Horticulture division of Texas A&M University. However, an interesting ability to self-sow helps keep cosmos gardens blooming year after year.
A few annual flowers have a natural ability to produce and drop seeds, which helps keeps plants growing in the same area year after year. Pink cosmos are among the flowers that have this ability to self-sow seeds, according to the National Gardening Association. While cosmos may continue to grow year after year, each year produces a new generation of flowers, rather than the same plants surviving through the winter.
Help from Gardeners
Gardeners can help keep their cosmos gardens alive throughout the year by locating seeds dropped by the cosmos. Work those seeds into the soil to help produce flowers for next year's garden.