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As a gardener, you will want to know the difference between annual, biennial and perennial plants. Why are these terms important? Whether a plant is an annual or one of the three types perennials makes a big difference in when and where you plant them in your landscape. If you are looking for a plant to keep its look during the winter, you want an evergreen perennial. If you plant to move plants around from year to year, you want an annual. The distinction between types of plants gives you information on when and where to plant, and how to care for your acquisitions.
Annuals
Annuals are plants that complete their life cycle within one year. That means they grow from a seed, into a mature flower, set fruit that contains a new seed, and then die within that year. Some common annuals are vegetable plants like radishes and cucumbers, or flowers like bluebonnets, zinnias or pansies.
Biennials
Biennials complete their life cycle in two years. This type of plant sprouts from seed and grows into a plant in the first year. In the second year, they flower, set seeds, and die. Onions are this type of plants, as well as parsley, artichokes, foxgloves and hollyhocks.
Perennials
Perennials are the longest lived of the annual, biennial and perennial plants. Perennials live more than one year. Some live 3-5 years, and some live up to 50 years or more. This category is further subdivided into herbaceous, deciduous and evergreen perennials.
Herbaceous perennials die to the ground during the wintertime and then grow back the next spring. In central Texas, Asclepius tuberrosa or tropical milkweed is a herbaceous perennial. If you’re lucky enough to know someone with one of these plants, you can grow them from seeds.
Deciduous perennials lose their leaves during the winter, but regrow their leaves in the spring. Oak trees and beautyberry bushes are two examples.
Evergreen perennials keep their leaves all through the winter. Irises and rosemary plants are evergreen perennials.
Growing Zone Differences
Notice I said “in Central Texas”. Your growing zone makes a difference for many plants whether they are herbaceous or evergreen, and can even make a difference in whether a plant is an annual, biennial or perennial plants. For example, here in central Texas, lantanas are herbaceous perennials. Further south, they are evergreen, and further north, they are annuals. Hibiscus and bougainvillea are annuals here, but further south, they are perennials. Here, tomatoes are considered an annual but further south, they are perennials growing year-round.
Are Vegetables Annuals, Biennials, or Perennials?
Vegetables can be annual, biennial or perennial plants. Most vegetables are annuals. Corn, tomatoes, broccoli, okra, cucumbers, watermelons, and beans are all annuals. Even though most vegetables are annuals, some are perennials. Artichoke, asparagus and rhubarb are examples.
And many fruits are perennials. Blackberries, raspberries, figs, and peaches are all perennials.
Which are Better: Annuals, Biennials, or Perennials?
Being lazy by nature, when I have to choose between an annual, biennial or perennial, I tend to choose a perennial. I really like perennials because you don’t have to replant them every year. You have a lot of plants you can count on to come back year after year. Until they don’t come back. I have lost plants because of an especially cold winter even though they are usually an herbaceous perennial. Or sometimes a perennial will just die. Chalk that up to the 500 dead plant count you need to become a “master gardener”.
It is usually best to plant perennials in the opposite season from when they bloom. For example, irises bloom in the spring, so it is best to plant or divide them in the fall. Asters bloom in the fall, so divide or plant them in the spring.
Perennials will not be at their best when you plant them. I’ve heard the saying many times that in the first year, perennials sleep. In the second year, they creep. In the third year, they leap. Sometimes you’re just about to give up on a plant when it is just about to leap! And be sure to leave enough space for the expected size of the perennial because you don’t want to have to move it just as it is reaching its prime because moving it probably will set the plant back a bit.
Advantages of Annuals
On the other hand, annuals have advantages too. One advantage of many annual flowers is that they bloom for a longer period of time than perennials. So, I also have some annuals in my garden. But in general, I try not to have to plant a lot of annuals to keep the garden looking lovely.
Some annuals, like the Cosmos plant, reseed so vigorously, they almost become weeds. If I have to pull weeds, I’d rather they be of pretty plants than of plain old weeds. Unless they grow using rhizomes. Then, they are a bother. For more on weeds, take a look at this post.
Annuals have the advantage that since they only live one year, you can plant them in one place and then decide to change to another place next year. This year, I wanted to plant my tomatoes in a new place because I wanted to rotate where they were planted for good crop rotation. I planted some of my tomatoes between my rose bushes. I didn’t have to commit to planting tomatoes there year after year.
Perennials that Flower
I prefer flowers whenever I can have them, so I plant perennials that bloom in most cases. By having a variety of different perennials with differing seasons of blooming, I can have blooms most times of the year. Irises bloom in the spring, wild bergamot in the late spring, obedient plant in the summer and Mexican bush sage in the fall.
Caring for Perennials
Perennials are not care-free, however. Some perennials do best if you divide them every few years. Irises are an example. They are evergreen perennials. Because the rhizomes require sunlight to bloom, they can get so crowded that they don’t bloom well. When that happens, they need to be dug up and spread out to ensure a good bloom. Some perennials can be pruned to keep them healthy and growing.
My Obedient Plants, not very obediently, spread at a rate faster than my limited garden space can allow. I have to dig up many baby plants and give them away or compost them so that I can plant some other things.
Another not so obedient perennial is Greg’s Mistfloweer. I love the purplish blooms and so do the Queen butterflies as well as many other butterflies, but this vigorous spreader grows in all directions, including between and past my border rocks and into the pathways. It’s starting to sound like I have a lot of vigorous spreaders! Oh, well, they are a dependable source of give-away plants.
The next time you are in the nursery, you are sure to see signs saying annual or perennial. Pick out the plants that best fit your needs.