Annual refers to a plant which completes its life cycle, from germination to the production of seed, within one year, and then dies. Summer annuals germinate during spring or early summer and mature by fall of the same year. Winter annuals germinate during the fall and mature during the spring or summer of the following calendar year.
Winter annuals germinate in early to late fall, live through the winter, then bloom and set seed the following spring. These plants grow and bloom during the cool season months when most other plants are dormant or other annuals are in seed form waiting for warmer weather to germinate. Winter annuals die after flowering and setting seed.