Annuals and Biennials

©2006 Publications International, Ltd. Black-eyed Susans produce a wealth of summer flowers and will freely reseed themselves. See more pictures of annual flowers.

Annuals are flowers that bloom the first year they are planted, often flowering just a couple of months after sowing. Most annuals are started indoors or in greenhouses in late winter or early spring.

Biennials like cup and saucer, some foxgloves, and some hollyhocks produce only greenery the first year. During the second year of growth, they flower and set seed destined to become the next generation. If you allow plants to self-sow for at least two years, you will have a steady supply of blooming plants.


Types of Annuals and Biennials

Tender Annuals

Some annuals, called tender annuals, are killed by frost. They grow in hot weather and are started indoors or in greenhouses and then set out in the garden after the danger of frost passes. Some of the faster-growing tender annuals, such as zinnias and marigolds, can be sown directly into garden beds (after the frost in spring) for bloom or use all summer long. This depends on many factors, including where you live and how long summer weather lasts.


Hardy Annuals

These annuals have some built-in frost tolerance. They are often, but not always, planted outside from seed a few weeks before the final frost, but sometimes they are started indoors in warmer conditions, hardened off for a good adjustment, and planted outside during spring.



Sown in summer or fall, biennials, such as sweet william, develop their roots and foliage and live through the winter. Then they come quickly into a spectacular but short-lived period of bloom in spring. They tend to self-sow, providing a constant supply of plants. Hardy annuals grow like biennials where winters are not too cold.

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