The difference between annuals and perennials is how long they last. Annuals only live for one season after they are planted, while perennials can last multiple growing seasons. With an annual, it goes through the entire process in a single year, including sprouting, seeding, flowering and dying. Perennials don't last quite as long during the growing season but come back for multiple years.
Near the end of the growing season for annuals, the flowers yield seeds. These seeds are used to grow annuals again the following season. When the flowers start producing seeds, it is a sign that the growing season is just about over. Some popular annuals are marigolds, zinnias and impatiens.
Some popular perennials are daylilies, mums, roses and peonies. It is important to know what perennial varieties grow well in the geographic region. Look around at other homes or businesses in the area to find out what perennials are found often and seem to be growing well year after year.
Aside from annuals and perennials, there are also plants known as biennials. These plants grow for a total of two seasons. They grow in the first season and bloom in the second. It is a good alternative to annuals, though they don't last quite as long as perennials.