The term `Annual` describes a plant whose entire life cycle, from seed germination to the plant`s death, takes place within one year. This means they come up in the spring, grow, flower, set seed and then die after the frosts in the fall.
There are many plants used as annuals in northern climates that are in fact perennial if planted far enough south where they do not experience the damaging effects of frost. These are termed tender perennials used as annuals. These include such plants as geranium, impatiens, vinca, coleus, and lantana. If one wants to save these plants from year to year, they would need to be dug up, potted and brought indoors or cuttings taken from the plants, rooted, and the resulting plants overwintered indoors.
There are a number of annuals that may act like perennials because of the large amount of seed they drop in the fall. This seed remains viable over the winter and new plants emerge in and around the area where the annual was planted the previous season. Plants like cleome, snapdragon, amaranth, cosmos, and petunia are examples.
Those that are able to withstand frost are known as `Hardy` annuals. The seed of these may be sown directly in the ground where they are to grow.
Those that cannot withstand frost are known as `Half-Hardy` annuals and the seed of these is usually sown in tray or pots, in a greenhouse or indoors, where they can be protected from frost until they are planted out in their growing position, once any danger of frost is past.
Annuals are traditionally regarded as a quick and inexpensive means of achieving colour and filling gaps in the garden. They can bring life to any garden within a few months or, as cut flowers, any home. Although short lived, a large number of these plants flowers profusely over many weeks or even months. While most are used in bedding displays, containers and hanging baskets, some varieties with a trailing habit are particularly striking grown up a support or allowed to sprawl over a bank.
If you want plants that come come to flower quickly and provide a long season of blooms, choose annuals. They are among the most adaptable of garden plants, demanding little more than good light, sufficient water, and reasonably fertile soil. Even if your conditions fall short of this ideal, you will likely find annuals that will work for you. In fact, some of the most striking annual gardens are found in what would appear to be the most inhospitable sites.