What’s the Difference between Annual and Perennial Plants?
When planning your garden, one of the most crucial decisions you’ll make is choosing between annual and perennial plants. Actually, that's not entirely true. You can have a garden that is gorgeous and filled with only annuals. You can have just perennials. Most likely, you'll have a mix of both. But knowing what type of plant you are planting is important in your garden planning.
While both types of plants play important roles in creating a vibrant and diverse garden, they have distinctive growth patterns, care requirements, and lifespans. Understanding the differences between annual and perennial plants can help you maximize your garden’s potential and tailor your choices to your gardening goals. It will also save you time and money, too!
What are Annual Plants?
Annual plants complete their entire life cycle in just one year. They germinate, grow, flower, produce seeds, and die all within a single growing season. These plants need to be replanted each year which means you can mix it up year to year. Annual plants are often used to add seasonal color, texture, or variety to the landscape every year.
Think of it this way: they are the party girls in the garden. They are big, blowsy, colorful, and showy because they have a very short time to get it all done. Afterall, their whole purpose is to set seed before the first frost – so they don't have much time. As a result they often have gorgeous flowers and grow very quickly.
Popular examples of annual plants include:
Marigolds
Petunias
Zinnias
Sunflowers (most but not all)
Lettuces
Dill
Annuals are often used in flower beds, hanging baskets, and container gardens to add instant, vibrant color. They can be popped in between perennials to give a garden bed a boost of instant color. Because they only live for one season, annuals typically require more attention during planting and care, as they need to be replanted each year and may require regular watering and fertilization to thrive.
What are Perennial Plants?
In contrast to annuals, perennial plants live for multiple years. These plants typically bloom for a specific period during the growing season, but unlike annuals, they return year after year without the need for replanting.
There are two main types of perennials:
Herbaceous perennials: they die back completely in the winter months, and then regrow from their roots in the spring
Woody Perennials: their stems remain above ground and overwinter (shrubs, trees, hydrangeas)
Popular examples of perennial plants include:
Lavender (woody)
Hostas (herbaceous)
Peonies (herbaceous)
Roses (woody)
Perennials offer the benefit of being low-maintenance once established. While they may require care and pruning, they will return year after year, saving you time and effort in replanting.
What Are Biennial Plants?
Biennial plants complete their life cycle over two years. In the first year, they typically focus on growing leaves, stems, and roots, but they do not flower. In the second year, biennials flower, produce seeds, and then die after completing their cycle.
Popular examples of biennial plants include:
Foxglove (Digitalis)
Carrots
Kale
Parsley
Hollyhock
Unlike annuals that need to be replanted each year and perennials that come back year after year, biennials are planted once and will return for a second year of growth before dying. This unique growth cycle can be an exciting addition to your garden, providing you with both foliage in the first year and flowers or seeds in the second year. Many biennial plants are vigorous self-seeders, too, and will pepper themselves around your garden.
Perennials sold as Annuals
To add to the confusion, many plants may be sold as annuals in your zone but are actually perennial in warmer climates. Take Agapanthus, for example. Here in Colorado, I can buy Agapanthus at my local garden center where it is sold as an annual for containers. BUT it is actually a long-lived perennial in zones 8-11. I grew it in my gardens in California for years with no protection. But here in Colorado, I have to overwinter it in the greenhouse.
This is a particularly common practice at big box stores, and it's something you should always look out for before making a purchase. Is this plant actually a perennial in MY location?
Location Matters
It's not just about growing zones. While the USDA Growing Zones are helpful, they aren't the full story. Just because a plant is "perennial in zone 5" that doesn't mean it will thrive in YOUR Zone 5. Afterall, there are Zone 5 locations in Colorado, California, Iowa, Wisconsin, New York, New Hampshire, Alaska… every one of those growing zones has similar low winter temperatures. But they all have different levels of rainfall, light, humidity, and soil compositions – all of which influence the health of the plants growing in that location.
So what is perennial in one location may not be perennial in another – even within the same zone.
How do you choose the right plant, then?
Research. When I'm in the garden center considering a plant, I first look at the tag and read everything on the tag. Then I do a quick Google search for the name of the plant (use the Latin name if possible) and my state. What do people say about that variety of plant in my area? If everyone seems to love it: great! It goes into my cart! But if there are people who caution that it doesn't thrive here, I look on for something else. Adding "site:edu" at the end of the search term can be really helpful, too, so that you get reliable results. This will often turn up your local Master Gardeners, too.
Key Differences Between Annual
and Perennial Plants
Lifespan:
Annuals: Complete their life cycle in one year, needing replanting every season.
Perennials: Live for several years, coming back year after year.
Biennials: Take two years to complete their life cycle. They grow in the first year and flower/seed in the second year.
Maintenance:
Annuals: Need to be grown and/or replanted every year and may require more frequent watering and feeding.
Perennials: Once established, perennials require less maintenance and fewer replanting efforts.
Biennials: Once planted, biennials typically require little maintenance in the first year, as they focus on root and foliage growth. In the second year, they need some care to help them flower and produce seeds.
Appearance:
Annuals: Often used for vibrant seasonal displays and color.
Perennials: Typically feature blooms that last for a few weeks to months
Biennials: In the first year, they might appear as a simple rosette of leaves. In the second year, they produce vibrant flowers or crops (like carrots or kale), which are often edible or ornamental.
Cost:
Annuals: Tend to be less expensive upfront but require yearly investment.
Perennials: Although they may cost more initially, they offer a long-term value as they return year after year.
Biennials: Like perennials, biennials don't need to be replanted every year, but they may require a longer wait before blooming or producing fruit. This makes them an excellent option for gardeners looking for a gradual, multi-year return on their investment.
Why Understanding
the Difference Matters
Knowing whether a plant is an annual or a perennial helps you make informed choices about what to plant and where to plant it. If you want a garden that changes with the seasons, adding a mix of both annuals and perennials can create a dynamic and diverse landscape.
In general: If you are looking for lower-maintenance plants, choose perennials. If you are looking for impact and high drama, choose annuals.
For Garden Design: Annuals can fill in the gaps and create bold statements, while perennials can provide structure and long-term beauty.
For Budgeting: Investing in perennials can save you money over time since they don’t need to be replanted annually.
For Maintenance: Understanding how each plant behaves can help you plan for the care and upkeep of your garden throughout the year, ensuring your plants remain healthy and productive.
We are always aiming for the "right plant, right place" goal (thank you, Beth Chatto). To make an informed decision, you must understand the differences between annual and perennial plants – in YOUR environment. You can make strategic decisions that suit your needs, whether you’re looking for immediate seasonal beauty or long-term, lower-maintenance growth. With the right combination of annuals and perennials, you can create a garden that thrives year-round while minimizing maintenance efforts. Happy gardening!
