Understanding the Difference Between Annual and Perennial Plants
Supertunia® Royal Velvet® petunia (annual). Photo by: Proven Winners.
All flowering plants follow the same basic steps in their life cycle. Annuals complete that cycle in one growing season, whereas perennials live on for three years or longer. But, if you begin studying the labels on your new plant or seed packet purchases, you’ll discover many twists on this basic definition. You’ll come across terms such as “hardy" and “half-hardy" annual, or tender perennial. Plus there’s a third plant category, biennials, that combines some of the characteristics of both plant types.
What is clear when comparing annuals and perennials is that neither is superior to the other. Integrating both types into your garden designs (along with shrubs and trees) gives you the best of both worlds and unlimited options in color, texture, form, and bloom time.
WHAT IS AN ANNUAL?
True annuals are plants that germinate, flower, set seed, and die all in one season. Their ultimate goal is to reproduce themselves (set seed), which is good news for gardeners because most annuals will flower like mad until their mission is accomplished. And, if you use methods such as deadheading to prevent seed formation, many annuals will amp up their flower production and continue to bloom profusely until the first frost arrives. Although you'll need to replant most annuals the following spring to get a repeat performance, some will readily self-sow and return for an encore, such as sweet alyssum, bachelor’s button, and forget-me-nots.
Snow Princess® Sweet Alyssum (annual). Photo by: Proven Winners.
Types of Annuals
Not all annuals are equal. They are typically subdivided into three groups:
- Hardy or cool-season annuals, such as forget-me-not and larkspur, thrive in the cool to moderate temperatures of early spring and fall and can tolerate exposure to light frost without being protected.
- Tender or warm-season annuals, such as marigolds and petunias, are native to tropical or subtropical climates and require heat to grow and thrive, often growing poorly during cold weather. To ensure their survival, it’s best to wait until late spring to add these plants to your garden beds or containers.
- Half-hardy annuals are most common and fall in the middle-of-the-road. They tolerate a wide range of temperatures, including periods of cooler weather near the beginning or end of the gardening season.
Why choose annuals?
- Growing annuals can be a great way to take gardening one year at a time; experiment with new plants and color schemes without making a long-term commitment.
- Annuals are perfect for temporarily filling in bare spots in established gardens or refreshing containers through the season.
- Add annuals to a vegetable garden for a splash of color, to fill in gaps when early-season crops are harvested, and attract pollinators to increase production of edible crops.
- Annuals provide nearly instant gratification, maturing faster than perennials or biennials, and often bloom from planting time until frost, and in some cases beyond.
- If you want a lot of blooms, annuals are the answer. They put all of their energy into developing flowers.
Learn more about growing annuals.
Dicentra 'Luxuriant' fern-leaved bleeding heart. (long-blooming perennial). Photo by AppletonOnfoot / Pixabay.
WHAT IS A PERENNIAL?
Unlike their short-lived counterparts, perennials are typically cold-hardy plants that will return again in the spring. They usually bloom for only one season each year (either spring, summer, or fall), but there are also reblooming and long-blooming perennials, such as fern-leaved bleeding heart (Dicentra ‘Luxuriant’).
When grown in favorable conditions, perennials often live a long time, but don’t assume they will last forever. Their life span is variable, and some may live for only three to five years. Perennials also vary greatly in terms of their care and maintenance. Some may need to be pruned and divided regularly to maintain their vigor and keep them tidy, while others are tough and undemanding, seeming to thrive on neglect.
Why choose perennials?
- Although perennials tend to cost more initially, they are a good long-term investment because they return year after year.
- Even perennials that don’t have a long life span can often be propagated by division* or reseeding to perpetuate their population.
- Most perennials require less water once established, which can be especially advantageous for those who garden in drought-prone areas and want to reduce their water consumption.
- Planting perennials that are native to your region offers the additional benefit of creating a welcome habitat for pollinators and local wildlife.
Don’t confuse perennials with biennials, such as dianthus, foxglove, and hollyhock. These plants take two years to complete their growth cycle before dying. Usually biennials do not bloom until their second year, but some behave like short-lived perennials and will flower their first year when planted early enough in spring or started indoors in winter.
Learn more about growing perennials.
HOW THEY COMPARE
|HARDY ANNUALS||HALF-HARDY AND TENDER ANNUALS||PERENNIALS|
|WHEN TO PLANT|
Spring or early fall. Seeds can be sown in winter in some climates.
Any time from late spring to midsummer, as long as there is little danger of frost.
Spring or early fall is best. It is difficult for plants to become established during the heat of the summer.
Typically one growing season, although they may self-sow and return for a second season.
One growing season.
Three or more years.
Cold-tolerant; can handle a slight freeze.
Intolerant of freezing temperatures.
Varies, but most plants can survive cold winters.
They thrive early and late in the season, when temperatures are too cool for most tender annuals.
A great addition to containers or a garden full of perennials, adding nearly instant color when perennials have stopped blooming for the season.
Provide a sense of continuity from year to year. Although they typically bloom for just a few weeks, their foliage and form contribute to the beauty of the garden throughout the year.
Pegasus® Begonia hybrid (tender perennial). Photo by: Proven Winners.
PLANTS THAT BREAK THE RULES
Not all flowering plants fall neatly into the categories of annual, perennial, or biennial. Here are a few that break the rules.
Tulips: Although most bulbs are considered to be perennials, tulips are often an exception. Native to Central Asia, they require cold winters and hot, dry summers to return each year. But in climates that don’t offer these conditions, they don’t rebloom reliably and are often treated as annuals.
Tender perennials: You may be surprised to discover that some of the most popular annuals may actually perform as perennials in certain regions of the country. These tender perennials, sometimes called “temperennials," are winter hardy in warmer growing zones but not in northern gardens, where they are typically grown as annuals or even houseplants. Many succulents and tropical plants fit into this category, such as begonias, Alternanthera, elephant ears, and agave.
“If you get right down to it, the label given the plant isn't important. What is important is how the plant performs in your garden," says Proven Winners’ horticulturist Kerry Meyer. “For some of you, the plants we call annuals might actually be perennial. To learn if the ‘annual’ you are looking at is an annual for you, you need to compare the plant’s hardiness zone to the zone in which you garden."
*Note: Make sure you check plant labels before propagating, because propagation (cuttings, division, or grafting) of trademarked plants is prohibited.
Annuals You’ll Love
Perennials You’ll Love
Annual Plants vs. Perennials and How to Use Them
Wi Buy Wirach Thn Phanth / Getty Images
What makes annual plants "annual" and perennial plants "perennial?" Well, the answer lies in their respective life cycles. "Life cycle" means the amount of time it takes a plant to grow from seed and end up, finally, bearing seeds of its own.
Botanically speaking, annual plants complete their life cycle within one growing season (typically, from spring to fall):
- You place the seeds from last year's flowers in the ground in spring.
- New annual plants sprout from the seeds.
- With proper care, during the summer, these produce flowers.
- Toward the end of the growing season (late summer or early fall), annual flowers yield seeds, signaling to the plants that their life cycle is complete. Having achieved their reproductive mission, they will die when the first hard frosts of autumn arrive.
- But in many cases, if you practice deadheading on them during the summer to foster reblooming, you can get a lot of value out of them as fall flowers in the early part of autumn. Deadheading, you might say, tricks a plant into blooming a little longer than its natural life cycle would call for.
What's the Difference Between Annual and Perennial Flowers?
Annual plants live for one growing season and then die, while perennials regrow every spring. The difference is genetic, and yet, a clever "plant gene therapy" technique can be used to change an annual into a perennial.
In 2008, scientists with the Flanders Institute for Biotechnology in Gent, Belgium, determined what makes plants either annual or perennial. The difference, according to plant geneticist Siegbert Melzer and his team, comes down to two critical flower-inducing genes that, when turned off, can make an annual plant regrow every year.
The rapid growth of flowers, and then seeds, is the strategy most annuals use to propagate from one generation to the next and one growing season to the next. Annuals experience "rapid growth following germination and rapid transition to flower and seed formation, thus preventing the loss of energy needed to create permanent structures," the researchers explained in a press release.
"They germinate quickly after the winter so that they come out before other plants, thus eliminating the need to compete for food and light," according to the statement. "The trick is basically to make as many seeds as possible in as short a time as possible."
Perennials instead build "structures" such as overwintering buds, bulbs or tubers, that contain cells that are not yet specialized and, when the next growing season begins, can be converted into stalks and leaves .
An annual uses up all of its non-specialized cells making flowers, and thus, after dropping seeds, it dies. The growth of the flowers is triggered by the plant sensing the length of day and amount of sunlight. When the light is just right, "blooming-induction genes" are triggered.
By deactivating two of the genes that induce flower growth in the thale cress, a flowering plant whose genome has been entirely sequenced, the researchers created mutant plants that "can no longer induce flowering, but . can continue to grow vegetatively or come into flower much later." Because the plants don't use up the store of non-specialized cells making flowers, they become perennials, able to continue to grow for a long time.
And, like true perennials, the altered annuals show secondary growth with wood formation.
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Here’s the difference between an annual and a perennial plantby Sam Schipani November 5, 2020 November 5, 2020
“Annual” and “perennial” are words that gardeners throw around all the time. If you are new to gardening, you may have nodded your head along to the lingo without being certain of the difference between the two. But what do these terms mean?
At the most basic level, an annual plant completes its life cycle of germinating, maturing, producing flowers or fruit, developing seeds and dying within the year. There are both winter annuals, which start this cycle in the late summer and die by the spring, and summer annuals that go through the same process in the summer months.
“Both types of annuals have a ‘live fast and die young’ approach to allocating their resources,” said Kate Garland, horticultural specialist at the University of Maine Cooperative Extension. “In other words, annuals are more likely to flower earlier and typically have a less robust root system.”
Perennials, on the other hand, live for many seasons. As such, they dedicate more of their resources towards establishing their vegetative, non-reproductive structures, especially their root system. The plants can be woody like trees and shrubs, or herbaceous. Perennials that Mainers might recognize include rhubarb, asparagus, maple trees, blueberries, cone flower, phlox, rhododendron and thyme.
The difference between annual and perennial plants is based on the genetics of the plant, either through evolution or breeding. However, the distinction between annuals and perennials is not black and white — it’s more of a spectrum.
Roughly between the two are biennial plants, which germinate set out leaves, stems, roots the first season overwinter and, finally produce a flower, fruit and seed the following year before they die.
“People are often surprised at some of the common vegetables that are biennials [like] carrot, onions, beets,” Garland said. “These all have a solid root system and aren’t plants we think of as flowering plants because we rarely give them a chance to flower. We usually harvest them the first season before they have a chance to overwinter and produce those flowers.”
There are crops that will behave as either a perennial or annual depending on how and where they are grown.
“Peppers, basil, perennials we grow as annuals [but if] you go further south and they just keep growing [and] turn into shrubs,” said Caleb Goossen, organic crop and conservation specialist at the Maine Organic Farmers and Gardeners Association. “Some people try to stretch the limits of what they can grow as a perennial here. Some folks can grow lavender outdoors many winters [by] protecting it somehow. Herbs like oregano can be like that, [too].”
Some common crops hover between categories.
“Onions are a great example of a group of plants that have different species or varieties with different life cycles,” Garland said. “Most of our traditional edible onions are biennial, but there are certainly a number of perennial onion family members, such as chives and walking onions.”
When choosing whether you want to plant annual or perennial plants, consider the long-term goals for the space. For crops, it takes time to get most edible perennials established enough to enjoy the “fruits” of your labor, so most gardeners opt for primarily annual crops.
“For example, asparagus harvest should be delayed until the second year after planting crowns you wouldn’t want to have to reset the clock and wait another two years to harvest asparagus because you didn’t select the right spot for it in the first place,” Garland said.
For ornamental crops, Garland said that most gardeners should go with a mix of annuals and perennials.
“While investing in perennial plants can get a bit pricey, annuals can be way more expensive in the long-run if you’re purchasing new plants every year,” Garland said. “Now is a great time to start native plants from seed outdoors. Annuals can be very rewarding to grow from seed either indoors or sown directly into the garden when the soil warms.”
Plus, having a mix of perennial and annual plants in an ornamental garden will keep it aesthetically lush and beautiful.
“With ornamental crops one of the reasons people choose annual [plants is that] many of them have been bred to keep on flowering,” Goossen said. “Each perennial plant usually flowers for one specific time period and then there are less flowers, [though with] modern breeding, more and more perennials that will rebloom later in the year.”
Ultimately, though, both annuals and perennials — and everything in between — have their benefits. The most important thing for gardeners is to understand the characteristics of each of their precious plants and balance their garden accordingly.
The key difference between annual and perennial plants is that annual plants live only one season, especially one year while perennial plants live more than two years. Another main difference between annual and perennial plants is that perennials are bushy plants, whereas annuals tend to be less bushy. Moreover, annuals are showier than perennials.
Some examples for annuals are poppies, marigolds, sunflowers, zinnias, and petunias while some examples for perennials are lilies, salvia, cranesbill, peonies, hydrangea, campanula, delphiniums, alchemilla, kniphofia, roses, peonies, and daffodils. Furthermore, perennials grow to attain more height than annuals, which are characterized by a normal height of about 10 to 15 inches. This is also a difference between annual and perennial plants.
While perennial wildflowers do not have the same visual impact that annuals have, they do last a very long time with less maintenance than annuals. Perennials are an excellent choice for larger areas as they still attract and help butterflies, bees and other pollinators.
Perennial species can be slow to establish and are unlikely to flower in the first year. The area can be cut once the flowers have died back in the autumn, but we recommend leaving the area undisturbed for as long as possible, ideally until February / March (before the first spring growth). When the area is left, dead flowers and stems provide a diverse environment which is a haven for wildlife through the winter months. In particular, it provides habitat for butterflies such as the Red Admiral and the Clouded Yellow which remain in their chrysalis during the winter months. Cut the area down to 10cm using a scythe, strimmer or mower, leaving the cuttings for a week before removing. This will allow them to dry and shed seeds back into the soil.
After twelve months, the sward should be well established and require little additional maintenance. Then follow the same annual cut pattern (either in spring or autumn depending on your preference). Over time, some species within the mixture may become more dominant due to environmental factors and natural selection. To encourage diversity, reduce the number of dominant plants to restore the balance.
Perennials in a Nutshell
- Return year after year
- Are low maintenance
- Attract and help pollinators
- The first season after sowing will not produce a great display
- Appearance improves every season
- Have shorter bloom times than annuals
Most annuals should be planted outdoors in the soil after the last frost, like morning glory and larkspur. Others, such as coleus and impatiens, should be planted indoors from seeds six to eight weeks before transplanting them outside in the garden. Most annuals will start growing at four to seven days, others may take up to four weeks. If starting your flowers from seeds feels like too much work, visit your local garden center. They'll begin stocking colorful annuals for both sun and shade in early spring, and most will continue to offer a variety of options straight through until the end of summer.
Some sun-loving annual varieties include geranium, petunia, salvia, and sunflowers. If your garden doesn't get much light, try planting begonia, calendula, pansy, and snapdragon, which are all considered shade-seeking flowers. And if you're just starting out, poppies, zinnias, marigolds, and cosmos are your best bet as these varieties are easy to grow.