Annuals vs. Perennials, According to Gardening Experts

Annuals vs. Perennials, According to Gardening Experts

Whether you have a garden or are interested in starting one, you're probably familiar with the terms annual and perennial. Both are used to describe the growth cycle of plants, but knowing the difference between annuals and perennials (and their lesser-known counterpart, biennials) will help you understand which is better suited to your gardening style and help you plan your landscape layout throughout the year. It will also determine the type of care your plants need at key points during the growing season.

What is an annual?

Annual plants complete their life cycle in one growing season and never come back. “It's a great way to add color and texture to your garden at a glance, because they tend to grow quickly,” says Kieran Avis, horticulturist at Longwood Gardens. There are a few types of annual plants that you are likely to encounter at your local plant nursery.

  • Annuals in cool season: These plants thrive in cool temperatures and can be used to add interest to your garden during the spring or fall. “Poppy, nigella, sweet pea, viola, and snapdragon are all great examples of cool-season annuals that will make your spring garden shine,” says Avis.
  • Warm season annuals: Also known as tender annuals, these plants enjoy the heat of summer. “Annual sunflowers, gouvrena, salvia, celosia, and zinnias are all great additions to make your summer garden special,” says Avis. Many warm-season annuals are native to the tropics.
  • Self-seeding annuals: These plants grow again the following year from seeds rather than from their roots like perennials. “Plants will drop seeds into your garden once planted, and those seeds will germinate on their own the following year,” says Avis. “Verbena bonarensis and some Nicotiana are good examples of this.”

What is perennial?

A perennial is a plant that lives more than two years and grows again every spring. While the flowers and leaves of perennials die over the winter, new growth emerges the following spring with minimal work on your part. “When positioned correctly, perennials can be divided and moved around the garden to create lush, immersive landscapes that will return year after year,” says Jeff Lorenz, founder of Refugia. These plants are usually planted during fall or early spring. Common perennials include hellebores, peonies, forsythia, daylilies, poppies, black-eyed irises, daisies, and hydrangeas.

What is a biennial?

Biennials are plants that need two seasons to flower. “They will send up grassy growth the first year followed by grassy growth and flowers the second year,” Avis says. After their second year of life, they die, which puts them in the middle of annuals and perennials. However, like some annuals, some biennial varieties drop seeds, perpetuating their life cycle in your garden. Common biennial plants include forget-me-nots, foxglove, and sweet william; Many vegetables, including cabbage, Brussels sprouts, and cauliflower, are also biennials

Annual vs. Perennial vs. Biennial

Because they have different life cycles, annuals, perennials and biennials have their own unique benefits in the garden.

Benefits of annuals

Annuals tend to have a long flowering period, showy flowers, and add long-lasting color to garden plots and containers, says Peggy Ann Montgomery, horticulturist at FlowerBulbs.com. Many of these plants can be grown from seed, which is a fun and inexpensive way to start your garden. If you don't want to grow annuals from seed, they are also often sold in flower, providing instant gratification for gardeners. “Many annuals are hardy and can be grown outdoors for early season color,” she says.

Benefits of perennial plants

The biggest appeal of perennials is that you only need to buy them once, whereas annuals are purchased every year. As perennials get larger and produce more and more flowers, they can be divided and turned into more plants. “Perennials cost more than annuals but are a great investment because they don't have to be replanted every year,” says Montgomery.

Perennials are also beneficial for your landscape. “Perennials native to your site have the added benefit of providing specialized ecological functions, including being host plants for different types of insects,” says Lorenz. Seed heads left over during the winter also provide forage for wildlife and allow plants to self-seed throughout the garden. “These plants are also deeply rooted and are wonderfully effective at managing rainwater in a way that most annuals are not,” Lorenz says.

Benefits of biennials

Although you may feel impatient waiting for them to bloom, biennials offer the perfect combination of benefits. They grow back like perennials and are usually as showy as annuals. “Biennials are another good tool for adding beauty to your garden,” says Avis. “It is important to supplement the plantings annually to ensure you get flowers every year, as biennials flower in their second growing season.”

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