Annual flowers do not come back every year. If you want a specific type of annual plant to be a permanent part of your garden, you will need to plant new seeds or seedlings each year. Perennials, however, will return year after year. Some flowers act as either an annual or a perennial depending on the geographic region. Some perennials may act as annuals when planted in warm climates that allow for quick growing and long flowering seasons. When used in colder climates that have shorter growing seasons these same plants perform their roles as perennials.
Definition of Annual Flowers
Marigolds, impatiens and petunias are examples of annual flowers. Annuals are plants that complete their life cycle, from planting to death, in one growing season. The entire flower, including the roots, stems and leaves, die when the weather turns colder. The only surviving part of an annual is the seed. Annuals tend to have more colorful blooms that last longer than the flowers of perennials. Their growing season usually runs from spring to autumn.
Definition of Perennials
Some examples of perennials are hostas and daylilies. These type of flowers grow for three or more years. The flowers don't last as long as annuals; however, some perennials -- like Lenten rose, thrift and rock cress -- have the added benefit of keeping their foliage year round. In most perennial, the entire top of the plant dies back, but the root system remains. This allows them to grow again the following growing season.
Annuals Versus Perennials
You may choose to plant annuals if you enjoy changing your garden year to year or using flowers that bloom quickly and last longer into the growing season. Perennials might be a better option if you do not enjoy planting new flowers every year due to the work or expense involved. Mixing the two types to ensure varied blooming times and continued foliage throughout the winter months is a great way to reap the benefits of each.
Some plants do not fit neatly into the category of annual or perennial. These plants are called biennials because they require two full growing seasons to complete their life cycle. The seed of the biennial plant usually produces a small plant or leaves without flowers in the first year. In the second year, this type of plant will fully grow the stem, leaves and flowers. The biennial begins to act like an annual in this second season, blooming then dying completely, leaving only the seed alive. An example is foxglove, which puts up a spire of bloom its second year, sets seed and dies off. Gardeners may mistake biennials for perennials because new plants develop from seed, often in the same area as the mother plant.