What Is an Annual Plant (vs. Perennials and Biennials)?

An annual plant dies after a year (or one growing season). Meanwhile, a biennial lives for two years and a perennial plant lives for three or more years. Expect to replace annuals or perennials grown as annuals every year. Perennials grown as annuals are usually plants grown outside of their standard temperature zone; they will typically grow for the part of the year that is their ideal temperature but will die when temperatures exceed their comfort zone.

Some annuals may act like perennials; instead, they are annuals that died, but before they did, they dropped seed, reseeding the planting bed or container for the next growing season. It only seems as if they return year after year. Some examples of these plants include violas, chamomile, poppies, and sunflowers.

Do Annual Plants Come Back or Die Every Year?

A true annual is a plant that completes its life cycle in one year. This means it goes from seed to flower and back to seed and dies in one growing season.

Annuals vs. Perennials: Understanding Garden Terms

The entire mission of an annual plant is to produce seeds to ensure the propagation of future generations. It sets pretty flowers to attract insects so that they can be pollinated. That is why deadheading or removing spent flowers before the seed matures induces the plant to set even more buds and blossoms, hoping to generate more potential seeds that will survive.

Some tender perennials, like the popular zonal geraniums (Pelargonium), are grown annually in colder climates because they cannot survive cold temperatures and conditions. Many perennials only grow foliage in their first year and start flowering in their second. For a perennial to be worth growing as an annual, it must flower profusely in its first year of growth. Pansies, lantana, alyssum, tomatoes, and peppers are all tender perennials grown annually.

The distinction between annual plants and perennials can be blurred, but whether your plant is a true annual or a perennial that is grown annually, you can expect to have to replace it each year.

Types of Annual Plants

For many annuals, their death knell is the first frost. Other annuals act differently to weather, like annuals that can handle a light frost, cool-season annuals that die back in sweltering temperatures, or warm-season annuals that need consistent heat to bloom. Most vegetables are annuals, although some notable exceptions are rhubarb, asparagus, and artichokes.

• Hardy annual plants: Hardy annuals can withstand a little frost without being killed off and will continue to bloom and set seed into the following year. However, they do not continue indefinitely and usually die shortly after their second year begins. Bachelor's button and Victoria blue salvia are examples.
• Cool and warm season annuals: Annuals can be divided into cool and warm season annuals. Although they may live for the entire growing season, they may not flower the whole time. For example, pansies will fade as the summer heats up. Zinnias won't even start flowering until the nights stay warm.
• Annual vegetables: Many vegetables and herbs are also annual, such as beans, basil, cilantro, and cucumbers. Even most perennial vegetables are grown as annuals, partly because they are only hardy in the warmest climates but also because they are required to continually produce flowers and fruits that are harvested rather than allowed to go to seed. All this effort eventually exhausts plants like tomatoes and eggplants.

Why You Should Grow Annual Plants

Annual flowers tend to bloom nonstop, especially if you deadhead the plants. Growing annuals will help keep your garden in bloom all season. They are popular for containers and hanging baskets because they remain attractive all season.

Annual flowers also allow you to have a different garden every year. Perennial plants come back each year and remain a constant in your garden. If you want to try a new color scheme or simply experiment with new plants, annuals allow you to do that without making a long-term commitment. They also tend to be less expensive than perennial plants.