There are three ways to characterise how long a plant grows--annual, biennial, and perennial. A wide variety of plants fall into each of these broad categories. Carnation (Dianthus), a floral and garden flower with pink, red, yellow or white blooms, like all plants, fits into one of these categories. But which category best describes carnations? And what do annual, biennial and perennial mean?
Annual and Biennial
An annual is a plant with a life cycle lasting only one growing period All in one year, the plant grows from seed, produces foliage and flowers, then dies. Annuals must be replanted every year. Biennials, on the other hand, need two years to go through their life cycle. A biennial grows from seed the first year, producing foliage, but doesn't bloom until the following year. Then the plant dies.
Perennials are plants that grow for many years without the need for replanting Usually, the foliage of the plant dies back each winter, but the roots live on in the soil. In the spring, new foliage appears. It's also important to note that some plants change their category depending upon where they are grown. For example, some plants are annuals in particularly cold parts of the world, but are perennials in warmer climes.
"Carnation" is not a category describing how long plants grow. Carnation is the name of a specific flower, also known as Sweet William or Dianthus. Carnations live for many years in USDA gardening zones 2 through 10, so they fall into the perennial category. They are sometimes called "hardy perennials" because they withstand frost well.
For gardeners, the fact that carnations are perennials is important. Because carnations live for years, gardeners plant them in long -term locations and don't worry about replanting or replacing them for many years. If given full sun, well draining soil of a neutral pH level, and moisture, carnations thrive. Removing spent blooms increases the plant's yield of flowers, and cutting the plant back to the ground when the flowering period is over protects it from especially cold weather.