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What Is the Difference Between Annual, Perennial, and Biennial Plants?

Annual Plants are a type of plant that live for just one season. In that brief period, they germinate, grow, flower, and set seeds for next year’s plants—mission accomplished! Unless they self-seed, they will need to be replanted every year.

Perennial Plants are the mainstay of many gardens. Plant them once, and they will return each year, bigger and better, until you finally accept that they need to be reined in. Not all perennials have the same lifespan. Some, such as lupine, columbine, delphiniums, and heuchera, are short-lived, lasting only three to five years.

Biennial Plants take two years to complete their life cycle. Some of the most popular biennials include Forget-me-nots and money plants.

Comparison Chart

There are advantages and disadvantages to growing annuals versus perennials. Let’s dig into this interesting topic.

Annual Plants

Annuals live for just one season. However, they supply you with a wealth of blossoms all season long. They are great fillers to pep up a tired-looking landscape during a lull in perennial flowering.

Pros

Planting annuals allows you to change the look of your garden from year to year. Pastel pinks and blue flowers one summer can be replaced with hot reds and oranges the next! What fun!

If you start a new garden from scratch, annuals can give you instant color while the newly planted perennials and shrubs get settled in. 

Annuals are also great for cutting gardens, giving you tons of blossoms to enjoy inside and share with friends. They also are the best for containers, windowboxes, and hanging baskets. 

Popular Annuals

Many annuals are easily grown from seed:

• Zinnias
• Marigolds
• Cosmos
• Poppies
• Sunflowers
• Calendula
• Nasturtiums

For more about the value of annual flowers, see this post.

Perennial Plants

Perennials are the mainstay of many gardens. Many are easy-going and will happily bloom in most situations. Unlike annuals, very few perennials will bloom constantly. Pay attention to bloom times so everything in your garden does not blossom at once and then is done for the season, leaving you with a garden of leaves. Foliage can have interesting colors and textures, but we all love flowers!

Not all perennials have the same lifespan. Some, such as lupine, columbine, delphiniums, and heuchera, are short-lived, lasting only 3 to 5 years before weakening and disappearing. 

If you have lost any of the short-lived perennial plants, it was not your fault. They are not programmed to last forever. On the other hand, peonies, daylilies, hostas, irises, and New England asters are just a few of the long-lived perennials that will last for generations if given proper care!

Popular Perennials

Look for popular, low-maintenance ones like:

• Yarrow
• Coreopsis
• Coneflowers
• Bee balm
• Black-eyed Susans
• Daisies
• Phlox
• Sedum
• Goldenrod
• Russian sage
• Catmint

When shopping for perennials to add to your landscape, ensure they are appropriate for your location. Does it get the right amount of sun? What is the soil like? Some like moist soil, while others hate wet feet, and some, such as succulents and cacti, need dry soil. 

To be sure a perennial is hardy enough to survive the winter, it helps to know your hardiness zone. Go to this page to find your zone by zip code. Cold isn’t always a bad thing. Some plants actually need a period of cold to initiate bud formation. 

Peonies, lilacs, and many fruit trees won’t bloom if they haven’t had a certain number of days below 32 degrees.

In the South, it helps to know your heat zone as well since some plants like it hot while others do not. Developed by the American Horticultural Society, heat zones track the average number of days above 86 degrees. Find your area on .

When Is a Perennial Not Perennial?

Tender perennials and tropicals are often considered as annuals.

Sometimes, a plant that might be perennial in a warmer climate is sold as an annual since cold weather will kill it, and it won’t come back next year. Some examples are petunias, geraniums, lantana, or impatiens, and even some vegetables such as peppers are tender perennials.

They will survive the winter only if you bring them indoors and grow them as houseplants until the weather warms and they can go outside again.

Biennial Plants

Biennials are plants that take two years to complete their life cycle. The money plant (Lunaria) is a great example. In the first year, it was a rough-looking, ground-hugging plant. In the early spring of its second year, it sends up a tall flower stalk with lovely purple blossoms.

Money plant flowers give way to flat circular seed pods that we let dry on the plant until late summer. The outer coverings can be pulled off, revealing the shiny silver inner membrane that holds the seeds. Gather the seeds to scatter where you want new plants, or let them drop from the old plant naturally. Next spring, the two-year process will start all over again.

Popular Biennial Plants

Popular biennials include:

• Forget-me-nots
• Foxglove
• Sweet William
• Most hollyhocks.

Our Advice

Don’t think of it as annuals vs. perennials! Grow a mix of annuals, perennials, and biennials to keep your garden blooming from early spring until frost. Making good use of the vast diversity the plant world offers is the key to having an interesting and colorful garden!