The primary difference between annual and perennial flowering plants is that annuals observe their entire life cycle, from seed to flower, within a single growing season while perennials perpetuate their life cycles between multiple growing seasons. Annual plants have to be replanted at the start of each growing season, but perennials will continue to flower year after year.
In some cases, flowering plants can be either perennials or annuals depending on where they are grown. Some flowers, for example, come back over multiple years when they are grown in warm southern climates, but die when grown in the colder northern climes.
The right time to plant annuals depends on the local climate. Generally speaking, they should be planted after the last frost so they are not destroyed by freezing temperatures. This varies from one place to another, so gardeners should learn the boundaries of each growing season.
Even though annuals die after a single growing season, they generally bloom longer than perennials. Whereas a perennial flower might bloom several times, often for just a few days each, annual blooms might last several weeks.
Examples of perennial flowering plants include daylilies and peonies. In terms of annuals, popular choices include marigolds, begonias, poppies, forget-me-nots and snapdragons. The best annual or perennial for one's garden depends on soil quality, precipitation, available sunlight and the amount of care required.