In the world of botany, the technical definition of an annual flower is one that completes its life cycle within one year. This life cycle includes germination, growth, flowering, setting seed, and death. In the gardening world, however, this term has a little wiggle room. When it comes to flower gardening, the term "annual" is generally used to refer to plants that bloom in their first year of growth and are used in the landscape for one growing season, then removed and replaced by new plants the next year. While some popular gardening annuals do fit the technical description, such as petunias and marigolds, there are also plants that are categorized as annuals because they are grown and used that way.
Perennials are prized for their returning habit, meaning they return year after year. Although perennials may die down in the winter, they grow anew each spring, and the gardener does not have to put forth the expense of repurchasing them or the effort of replanting them. While this is certainly a desirable trait, perennials' downside for many gardeners is their relatively short bloom time, and in some cases small blooms that don't make much of an impact on the garden as a whole.
Annuals, on the other hand, are prized for their ability to make a dramatic, colorful impact on flower gardens. Because they tend to have larger and/or more blooms and a longer blooming season, annuals are often planted in mass groupings to create large strokes of bold color. Many annual plants bloom nonstop from spring until frost, making them a very attractive choice for the gardener who wants to fill his beds with dramatic color from spring until fall.
Naturally, different annual plants will have different light, soil, water and temperature requirements. However, there are some general guidelines you can follow to keep your annuals growing and blooming their best.
While many annuals can be grown from seed, established, nursery-grown plants will fill your beds with flowers much more quickly. Established plants are often sold in flats of 18 or 24 at a very economical price. While annuals sold in flats are typically very young and small, they grow very rapidly and will fill your beds with flowers seemingly overnight.
Observe the sunlight patterns in your flower beds and plant accordingly. Some annuals require full sun, others partial sun, and still others mostly shade. Choose plants that will grow well in your beds' lighting conditions, and plants that grow well in your part of the country.
Annuals work hard all season long providing blooms for your beds, often for many months at a stretch. All that blooming requires fertile soil and a good fertilizing now and then. Liquid fertilizers are very easy to mix with water and apply when you water your annuals. Look for a fertilizer specially made for flowering plants.
You don't have to limit your annuals to beds only. Use a little creativity when planting your annual flowers. Try them in hanging baskets, pots, window boxes and wall pockets.