What makes annual plants "annual" and perennial plants "perennial?" Well, the answer lies in their respective life cycles; that is, the amount of time it takes a plant to grow from seed and end up, finally, producing seed 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 course of 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 essentially tricks a plant into blooming a little longer than its natural life cycle would call for.
The Difference Between Annual Plants and Perennials
Thus the difference between annual plants and perennials. For perennials grown from seed usually do not produce flowers in their first year (nor do biennials). That is, they have a longer life cycle.
Perennials make up for their reproductive tardiness by flowering more than one year.
Some plants that are perennials in their native (for example, tropical) lands are treated as if they were annuals in colder regions (which is, in fact, how they function there, not being cold-hardy). Here, one might say that function trumps botany.
For example, lantana plants are, technically, perennial, but they are treated as annual plants in regions far to the north of their ancestral home -- regions too cold for them to survive the winter. They are raised in heated greenhouses until they flower, at which time they are sold to the gardening public.
Some folks understand this distinction but still have trouble remembering the terminology. If you can't ever seem to remember which is which, use the following as a mnemonic device:
- The root in both words, "annual" and "perennial" (that is, per-annual) is the Latin word for "year," annus.
- Annual plants are thus those that last for a portion of but a single year (even in their native climates).
- Perennial plants have something extra: that "per" in their name. The per- prefix in Latin intensifies or adds to what comes after it. So perennials, given the proper conditions, will live extra years, when compared to annual plants. Or think of it this way: they persist longer.
Which One Is the Better Deal for Consumers?
Garden centers tend to sell perennials individually (in pots), while annuals are more commonly sold in six-packs.
We call such annuals "bedding plants," because homeowners and businesses use them to create instant planting beds packed with colorful flowers. You will generally pay more for perennials than for bedding plants (but annuals sold in hanging baskets, such as fuchsias, also cost more than bedding plants).
Perennials cost more not only because they offer more value (due to their greater longevity), but also because nurseries invest more time and energy into growing them. Remember, they do not bloom during the first year of their lives, so nurseries are carrying them in stock and caring for them for a significant period of time before they can move them as flowering plants that the public will buy. In the long run, it may be a better deal for consumers to buy perennials, because they do not have to be replaced as often as annuals do (assuming that you care for them properly).
How Colorful Annuals Are Used in Landscaping
Some people who have been gardening for many years despise annual plants. This fact is somewhat inevitable, as those proud of their gardening knowledge and skills will always be on the lookout for new things to try. They view most annuals as commonplace and trite. Oddball perennials that "lesser" gardeners have never heard of are more their style. That is their right, but when such attitudes are cavalierly expressed on the web, newbies can wrongly be shamed into avoiding popular plants such as impatiens.
But dirt-common or not, annual plants do have a place in landscaping. They inject quick, long-lasting color into the landscape in areas where, otherwise, one would find the dreaded empty spot. For example, you may have a spot in your flower bed that displays wonderful color in spring (thanks to spring bulb plants, for example), but that looks rather boring once the spring flowers fade. Eventually, you may be able to insert a new perennial here that will pick up the torch and furnish floral color in summer. But in the meantime, annual plants may be just the solution to cover up the gaping hole.
In addition to impatiens, other annual bedding plants commonly found at garden centers include the following (most of these are usually sold in six-packs, but there are exceptions, most notably in the case of geraniums, which are sold in pots):
- Sweet alyssum
- Red salvia
- Bachelor buttons
- African and French marigolds
- Wax begonias
- Love-lies-bleeding (Amaranthus caudatus)
- Moss rose (Portulaca grandiflora)
- Blue ageratum