Have you ever noticed that some flowers need to be planted each spring, while others pop up all by themselves year after year? That’s because some of them are annual plants and some are perennial plants.

Annual plants are plants with a life cycle that lasts only one year. They grow from seed, bloom, produce seeds and die in one growing season. They then need to be replanted each spring.

Most annuals bloom for a long time. They provide beautiful colors from spring through fall and are popular with flower gardeners. Some favorite annuals are petunias, marigolds and zinnias.

Perennial plants live for more than two years. They return year after year and continue growing until they reach maturity, which varies by plant but averages three to five years.

The term “perennial” refers to herbaceous (“green”) plants since woody plants, such as trees, are perennial by definition.

Unlike annuals, perennials tend to bloom for just a short time — one to three weeks — each year. Examples of popular perennial flowers include tulips, asters, black-eyed susans and lilies.

Perennials generally do not have to be replanted each year. However, some gardeners choose to replace certain perennials, such as the perennial flowers mentioned above, every three to five years if they start to decline.

Hardier perennials might return year after year for 20 years or more. Perennials have structures, such as bulbs and rhizomes, that allow them to survive for many years.

Perennials can be divided into two categories. Deciduous perennials, such as the perennial flowers mentioned above, grow part of the year and fall dormant the rest of the year. Evergreen perennials, such as pine trees, grow year round.

Some people have a hard time remembering the proper term for each type of plant. Because annual means “yearly,” some people think annual plants keep coming back each year on their own. Annual plants actually get their name because they only have a one-year life span.

Perennials, on the other hand, come back year after year. Since they don’t have to be planted each year, they’re more permanent. Some people remember perennials by remembering that they’re more permanent!

Just when you think you understand the difference between annuals and perennials, though, you should know that there’s yet another classification! Biennial plants have a two-year life cycle.

They grow as green plants their first year, survive the winter and then bloom the following year. After they bloom and produce seeds, biennial plants then die. Examples of biennial plants include foxgloves and hollyhocks.

Some plants that are perennials in their native region may be considered annuals in other regions. For example, snapdragon is a plant that may be a perennial in a warm climate where it can survive the winter but may be an annual in colder climates where it dies in the winter.

These types of plants are sometimes called “half-hardy annuals” or “frost-tender perennials.”