What is the Difference Between Annuals, Perennials and Biennials

Understanding the differences between annuals, perennials, and biennials is essential knowledge for any aspiring gardener. Each type of plant has a unique life cycle and growth pattern, contributing differently to a garden’s overall aesthetics and maintenance needs.

I largely base my plant choices in my gardens around these three categories. Annuals and biennials are great for a splash of color, while perennials add substance and depth to any garden bed.

Ahead, learn all about annuals, perennials and biennials from two landscaping experts Ricky Lateurrer from Lateurrer Gardens and Landscaping and Joyce Corbett from Class Courtyards.

What Is an Annual Plant?

An annual plant completes a full life cycle in a single growing season. Annuals aim to reseed themselves and do not go dormant and return in the spring. Instead, they germinate, flower and produce seeds within a single season. These seeds then begin a new annual cycle in the spring, continuing to set seed for future plants. “Annuals are my favorite part of my garden,” Corbett says. “I have fun picking out new ones each year.”

Some annuals are perennials grown outside their normal United States Department of Agriculture (USDA) Hardiness Zone. “A lot of our annuals in New England are considered perennials in the South,” Corbett says. Because they cannot withstand freezing temperatures, these ‘winter annuals’ will live in colder climates during spring and summer months and then die off in winter. They will not regrow in the spring and require annual replanting.

How long do annual plants live?

A growing season or a year, depending on the plant and climate.

When to plant annuals

“You’ll want to plant annuals in the spring,” Corbett says. When spring actually occurs will depend on the USDA Hardiness Zone in which you live. In Southern California, this could be March, whereas in Northern Maine, it would be April or May.

What are common annual plants?

Begonia, Petunia, Lantana, Impatiens, Sunflowers, Zinnias and Marigolds are popular annual flowering plants.

Does an annual plant come back every year?

No, an annual plant does not come back every year. Annuals will not regrow and need to be reseeded or replanted each year. What they lack in longevity, they make up for with long flowering periods. “I think of annuals as a seasonal decoration that spruces up a garden,” Lateurrer says.

What Is a Perennial Plant?

A perennial plant lives at least two years, but there are some that can survive for 10 to 15 years or longer once planted. Perennials grow and flower through spring, summer and fall, then go dormant during colder months.

Perennial shrubs may lose their leaves, but woody growth remains. Other perennials lose all green growth during winter, but regrow from dormant root systems.

How long do perennial plants live?

At least two to three years, but some can live for decades. Most perennial flowers live between two and ten years, while shrubs can live longer. “I’ve dug up perennials from gardens that have been there for over 20 years,” Lateurrer says.

When to plant perennials

“[Planting perennials in] either spring or fall is a good time,” Lateurrer says. “You want to avoid the heat of the summer.” If you’re excited to see flowers right away, plant in the spring. If you can wait for flowers, plant in the fall to avoid watering all summer while the plant establishes. “You’ll really save on your water bill by planting in the fall,” Corbett says.

What are common perennial plants?

Perennial flowering plants include Peony, Daylilly, Iris, Seedum, Hosta, Phlox and Lavender. Perennial shrubs include Hydrangea, Azalea, Rhododendron, Butterfly Bush, Forsythia, Lilacs and Roses.

Do perennial plants come back every year?

Yes, perennial plants come back yearly. These hard-working, low-maintenance plants come back every year for at least two years, typically more.

What Is a Biennial Plant?

Unlike annuals, biennial plants take two years to complete a full life cycle. Generally, the first season is spent growing roots, leaves and stems, while the second season is devoted to flowering, growing and setting seeds.

How long do biennial plants live?

Biennials live for two years.

When to plant biennial plants

Summer or fall are ideal times to plant biennial plants. As long as they have enough time to establish roots and some growth before a frost, they will return to flower and seed in the spring.

What are common biennial plants?

Black Eyed Susans, Hollyhocks, Foxglove, Sweet William, Honesty, Delphinium and Evening Primrose are popular choices for biennial plants.

Do biennial plants come back?

Yes, biennial plants come back. The same biennial plant will return for one season after going dormant during winter. However, biennials can reseed and continue to grow as new plants. The Black Eyed Susans I planted a few years ago keep reseeding and spreading. The original plant is not alive, but through reseeding, Black Eyed Susans return each year.

FAQs

Annuals, perennials and biennials: Can you plant them in pots?

Yes, you can plant annuals, perennials and biennials in pots. Flowering annuals can, and often are, planted in pots. Perennials and biennials are typically planted in the ground to protect dormant root systems. However, some can be grown successfully in pots. A good rule of thumb is to choose cold-tolerant plants at least two zones colder than the climate you live in. This way the root system will withstand the colder soil temperatures in a pot.

Annuals, perennials, and biennials: Which are easiest to care for?

Perennials are the easiest to care for. Once established, perennials will return year after year. Lateurrer finds perennial favorites Daylilly, Hosta and Iris to be “the most low maintenance and drought tolerant.”

About the Experts

Joyce Corbett is the owner of Classic Courtyards in West Springfield, Massachusetts. She has over forty years of landscaping design and installation experience.

Ricky Lateurrer is the owner of Lateurrer Gardens and Landscaping, a full-service residential landscaping company in Longmeadow, Massachusetts.