The difference between annuals and perennials can cause confusion to the beginning gardener, especially when the issue of winter hardiness comes into play in the northern climates.
So, we go to the garden center, full of enthusiasm for the garden we are about to create. One of the more important items of information that we can gather from the plant labels is whether the plant is an annual or perennial.
The following should help dispel some of that confusion.
One of the main differences between annuals and perennials is that an annual is classified as a plant that completes its growth cycle in one year. Propagation is performed by seed. When annual flowers are cut or pinched off, the plant will respond by forming more blooms to assure that there will be seeds for the next year’s crop, basically the plant’s survival instincts kicking in. Because of the need to produce seeds, annuals generally bloom earlier and produce more flowers than perennials. Some plants that are treated as annuals in the north are actually perennials in warmer climates, however.
Perennial plants can live three years or longer, some will last indefinitely, some won’t. They have roots that live through the winter and they may or may not die back in the winter. Some perennials will bloom throughout the growing season if the blooms are removed, some won’t. While perennials can be started from seed, they are propagated for the most part by dividing or by taking cuttings. Perennials are often used in concert with annuals to provide contrasts and blooms during different parts of the growing season. When purchasing perennials, pay close attention to the USDA hardiness zone listed on the tag. Not all perennials will be suitable for all zones.
Biennials are plants that have a two year growing cycle. The plants grow roots and foliage the first year and flower and seed the second year. Biennials are usually purchased as second year plants from nurseries. Onions, usually planted from “sets” are an example of a biennial plant.
Pansies are also biennials. Some varieties have been bred to bloom the first year, however, blurring the lines between annuals and biennials.