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Annual vs Perennial Plants: Understanding the Differences

    Annual vs Perennial Plants: Understanding the Differences

    For those who are new to gardening, figuring out what’s an annual vs perennial plant is an important piece of information to take to the garden center. This knowledge helps determine how you plant up a new garden, or add to an existing plot, and it guides you to container arrangement options. Once you figure out what you need to put where, your seed and plant list will take shape. Where things get tricky is when you get into terms like hardy annual or tender perennial on a plant tag. What do they all mean? This article will share information about both annuals and perennials, and the variations that come with each definition.

    How to determine what’s an annual vs perennial

    Plant tags are your friend. Pay close attention to what they say to determine whether your plant is an annual or perennial. The tag will also state the best growing conditions in order for your chosen plant to thrive, such as full sun or full shade, dry soil vs wet soil, etc.

    a plant tag for a perennial plant
    The front and/or back of a plant tag should provide lots of information that you need in order to provide your plant with the best growing conditions.

    What is a perennial?

    Perennials are plants that come back year after year. They produce new, herbaceous growth on a part of the plant. Some die back in winter, like herbaceous perennials, and survive underground. Trees and shrubs are also considered to be perennials. Perennials (from hostas and asters to meadow grasses and coneflowers) generally last at least three years or more. Hardy perennials will survive extreme winter temperatures at the lower end of the zone map.

    eastern prickly pear cactus (Opuntia compressa)
    The Eastern prickly pear cactus (opuntia compressa) is a native perennial that flourishes in a protected area of ​​my neighbors garden. It is hardy down to -30°F (-34°C)

    Speaking of zones, when planting perennials, you want to make sure that they are compatible with your growing zone, meaning the lowest temperature during the winter months in which they will survive. With our evolving climate, it’s easier to go by the average minimum temperature of your region in winter as hardiness zone numbers have been shifting slightly over the years. Empress of Dirt offers a good primer on growing zones in the US and Canada.

    I live in a bit of a microclimate that’s protected by an escarpment. so I’m able to push my zones a bit. A local nursery should only be selling plants for your area, but this is something to be mindful of if you’re ordering online.

    What is an annual?

    An annual is a plant that lasts for one growing season. This can be confusing, since the word “annual” in other contexts means recurring once each year. And “season” doesn’t always coincide with the traditional seasons of spring, summer, fall, and winter. A seed will germinate, the plant will grow and flower, and then produce seed before dying off. Also referred to as “true annuals,” a lot of bedding and container plants, like zinnias, impatiens, and marigolds, fall under this category.

    If a plant you thought was an annual starts to grow in the same space come spring, that could be because those seeds from the previous year fell into the soil. This process is called self-sowing, reseeding, or self-seeding. This has happened in my garden with pansies, sweet alyssum, and cosmos.

    self-owned alyssum
    I love finding flowers in my garden that have self-sown from plants I grew the previous year. That includes this alyssum that self-seeded in my front yard garden.

    Annual sub-categories

    Annual plants are further divided into sub-categories. cool-weather or hardy annualswhich include a mix of vegetables (ie peas), herbs (ie cilantro), and flowers (pansies), don’t mind early spring frosts.

    Half-hardy annuals, such as cosmos, zinnias, and nasturtiums, are a bit sensitive to temperature fluctuations. You still need to keep an eye on them if there is frost in the forecast in the spring.

    china asters
    China asters are half-hardy annuals that are generally started indoors, but can be planted outside and don’t mind the cooler temperature fluctuations of spring.

    Warm-weather annuals or tender annuals thrive in the heat of summer, however, they are vulnerable and delicate when the thermometer trends downward. If they’re planted too early in the spring, for example, and there is a threat of a cold snap, they should be protected. Warm-weather annuals include vegetables and herbs, and flowers, like impatiens, marigolds, and petunias. The latter is considered a tender perennial in zones 9 to 11. Which brings us to tender perennials…

    What is a tender perennial?

    A tender perennial is a plant that will survive for more than one growing season (ie through the winter), but with some help in colder climates. In warm climates, these plants would be considered perennials. Sometimes tender perennials are treated like annuals and are either pulled or left in the ground where it’s unlikely they’ll survive over the winter months. If you want to keep them from year to year, they need to be dug up and stored or moved indoors and grown like a houseplant. Tender perennials that can be dug up and stored include dahlias, calla lilies, and caladiums. Those that can be kept indoors and grown as a houseplant through the winter include pelargoniums, begonias, coleus, and even veggies like peppers and tomatoes. Others, can be stored in a dormant state in a cool garage or basement.

    caladium in a planter
    Caladiums are tender annuals whose bulbs can be dug up in fall to be overwintered.

    What is a biennial?

    Now, to throw a bit of a curveball into the mix, there is also such a thing as a biennial plant. With these plants, it takes two years, or growing seasons, for the plant to complete its life cycle. In the first year, the plant will grow its roots, stems, and leaves. During the second year, the plant will grow flowers and/or fruit, and seeds, and then die off completely. Examples of biennials include some varieties of dianthus, parsley, kale, carrots,

    biennial dianthus
    I grew this biennial dianthus from seed. It flowered two years in a row and then the plant was done.

    Why choose an annual vs perennial?

    When searching for new plants, a good way to plan out the garden is to choose perennials for structure and four-season interest. They’re like the timeless investment pieces in a wardrobe that you can wear again and again. Once established, many have exceptional drought and heat tolerance, which helps them survive in extreme conditions. Perennial plants may come back each year, but depending on the size you purchase, they can take a while to reach their full potential. Check your plant label carefully to see the eventual height and width of a perennial so you can plan your garden accordingly.

    asters in a garden
    When choosing an annual vs perennial plant, figure out what the plant’s purpose is going to be. Are you planting for structure, to attract pollinators, to provide multi-season interest, or all three! Long-term, more perennials will result in a more low-maintenance garden.

    In the meantime, annuals are perfect for filling in those holes between perennial flowers and foliage. They’re also great for borders. And there are loads of annual options at the garden center for container gardening. Besides pots, I love to add annual flowers, like zinnias, to my raised beds. They attract bees and butterflies to pollinate the veggies, some make excellent cut flowers, and they look great.

    annual, perennial, and biennial herbs
    This garden provides a great example of annual (basil), perennial (chives), and biennial (parsley) herbs.

    Check out our categories of different annual vs perennial plants to grow

    Learn the differences between annual vs. perennial plants

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