Plant Life Cycles: Perennial vs Annual vs Biennial
All flowering plants follow the same basic steps in their growth cycle described as germination, vegetative growth, and reproduction. The time between each phase can vary depending on the type of plant.
Some plants grow back every year, some need to be replanted yearly and others take two years to flower.
These different types of flowering plant life cycles come from their root systems. Here you'll learn what each type means, as well as how they differ with time and growth patterns.
Annual plants complete a single lifecycle (i.e. germinate, flower, & set seed) in one growing season before they die.
Each year, they complete the same life cycle that starts with germination in spring or early summer, continues with vegetative growth, and finishes with reproduction (seed formation). When winter comes, annual plants die off and prepare to start their life cycle anew the next growing season.
They grow a taproot system that allows them to emerge from drought conditions because of their deep root structure.
They complete their growth cycle quickly because they don't have a special method to store energy, nutrients, or preserve moisture. So they require more maintenance and attention, especially soil preparation, weeding, and fertilizing.
Some examples of popular annuals include:
- Vegetables (lettuce, radish, peas, spinach)
- Flowers (snapdragon, marigold, impatiens)
- Grains (wheat, barley, rice)
Types of Annuals
Not all annuals follow the same growth patterns or time frames. There are three types of annuals:
- Cool-season annuals (Hardy annuals)
- Warm-season annuals (Tender annuals)
- Half-hardy annuals
Cool-Season (Hardy) Annuals:
Hardy annuals can be planted and will grow from early spring to fall. These germinate quickly and thrive during the cool/moderate temperature months of spring and autumn before dying off in winter under frost or snow.
These are used as winter bedding plants because they're cheap and easy to grow.
Some examples of hardy annuals include:
- Carnations (Dianthus caryophyllus)
- Snapdragons (Antirrhinum majus)
Warm-Season Annuals (Tender Annuals):
Tender annuals germinate quickly and thrive in warmer climates, but don't survive under frosts or snow.
They grow best when temperatures stay above 65 degrees Fahrenheit and require a lot of watering in the summer months to survive.
Some examples of Tender annual flowers include:
- Impatiens (Impatiens wallerana)
- Marigolds (Tagetes erecta)
These are halfway hardy and the most common ones. They can tolerate a wide range of temperatures, including those during the end or the start of the gardening time.
Are Planting Annuals Good for You?
- Most annuals have a long bloom season. They typically bloom all year until frost.
- Growing annuals in your garden is good to experiment with new plants, color schemes, and long lasting beauty (but it fades the second year).
- They are perfect for temporary filling up bare spots in your garden or containers.
- Many annuals can be added to a vegetable garden for filling bare spots or containers with beauty and attract pollinators.
- They mature more quickly than perennials or biennials. They bloom from planting to frost and in some cases beyond. They give quicker results.
- They totally concentrate on producing flowers. So if you desire a lot of blossoms in your garden, choose them.
Biennial plants complete a single growth cycle in two growing seasons. They spend their first growing season preparing for their second season by storing energy in their bulb or roots. In their second season, they produce flowers and drop seeds that complete their lifecycle, and hopefully, blooms from a new generation will come up.
When it comes to the roots of these types of plants they don't have the same root system as annuals, but they do have secondary roots called a fibrous root system.
This is beneficial because it increases the number of nutrients and water that the plant can absorb, which makes it easier for them to survive long droughts.
Some examples of biennial plants include:
Unlike their counterparts, perennial plants return year after year. Their seeds ripen when the blooms have finished and the petals have fallen away.
Perennials grow three different types of root systems:
Tap: A long main running stem that produces smaller offshoots from the tip. This is found in plants that grow into large trees or shrubs.
Fibrous: A network of roots that grows radially from a central stem. These can be further divided into smaller groups called 'fascicles' which are located either at the edge or in the middle of the root. This is found in plants that grow into smaller bushes or ground cover, such as lavender and thyme.
Rhizome: A horizontal stem above or below ground that shoots out roots from side buds. These are commonly called "creeping roots" because they grow close to the surface. This is found in plants that grow as ground cover, such as English ivy.
These three different types of root systems allow perennials to live a long time. But don't expect them to live forever, some may live for only up to 5 years.
Perennials tend to have more modest flowers and bloom for a shorter period of time, usually just two to six weeks before the ground freezes.
Some examples of perennials include:
- Trees (maple, rose, pine)
- Shrubs (lavender, thyme)
- Ground Cover (English ivy)
Why Choose Perennials?
- Perennial flowers return year after year, so its a good investment.
- Most perennials need less care once planted.
- Perennials are relatively less messy due to less dropping of their leaves.
- They can be propagated by division or seeding if some perennials have not a long life span. But check the plant labels first.
- Perennials endure harsher conditions and colder weather.
- Trees are the best example of perennials as they live for decades or centuries.
- Most perennials require less water once established, which is particularly beneficial to gardeners in arid regions who wish to save water.
- Planting native perennials not only provides a beautiful landscape, but it also attracts pollinators and local wildlife.
Annuals vs Biennials vs Perennials Comparison Table
Here is a simple comparison table of Biennial, Annual and Perennial.
|Life Span||1 Year||3+ Years||2 Years|
|Planting Season||Usually, spring to fall (seed can also be grown in winter)||Spring or early fall (difficult to establish in summer)||Autumn or Spring|
|Cold Hardiness||Mostly cold-tolerant||Varies, but most can survive||Survive average frost|
|Flowering Time||Same year flower||Every year flower||Following spring flower|
|Propagation Type||Mostly by seeds||Seed and cutting||Seed, bulb, tubing|
Life Cycle of Different Plants
Perennial plants tend to live the longest only because of their complex roots and foliage color, texture, form, and bloom time.
Biennials and annuals complete their life cycle quickly for this reason: more maintenance is required.
However, there's no specific way to tell which plant is which, but with this basic information you can look at the roots or type of foliage to make a good guess.
With so many different types of plants, it's important to keep them sorted in order to maintain your garden green all year long.
Perennial, biennial and annual plants all differ in the way that they grow and how fast or slow their life cycle is.
Annuals live for just one season but require regular replanting. Biennials take two seasons before they start flowering and need a lot of preparation beforehand such as being watered frequently.
Whereas perennial plants live for a long time and have several different systems to maintain their position in your garden or yard.
What is plants classification by growth cycle?
This classification determines how long they live and what type of environment they thrive in. Some are perennials, meaning that they will keep growing back every year. Whereas annuals need to be replanted yearly, and biennials will take two years.
Habitat is also important to consider when planting a plant as some prefer full sun while others prefer shade or dry spells. All these factors play into determining which type of plant you should choose for your personal garden.
What to grow in Drought Prone Areas?
Drought-prone areas are more susceptible to developing fungus and disease in a plant. In some cases, people also add a small amount of bleach to the water when watering to avoid further damage occurring to the plant. In dry spells areas, cacti and succulents typically grow.
Difference between Annual, Perennial, and Biennial?
The difference between annual, perennial, and biennial is the time they take to grow. Annual will need to be replanted yearly, whereas perennials will keep growing every year. Biennial usually takes two years before they flower.