How2Day: Field Guide to Garden Flowers

A well planned garden can be in almost continuous bloom. Jupiterimages/Photos.com/Getty Images
Some garden flowers do not return year after year. They are planted in the spring or early summer and fade by the first frost. Perennial plants, on the other hand, survive through the winter and return again in the spring or summer. Most gardens are designed to include both annual and perennial flowers. In this way the garden is in continual bloom throughout the growing season.

Perennial plants are hardy. Perhaps the clearest distinction between perennials and annuals is between the wisteria vine and the sweet pea. A wisteria vine is woody, dies back in the winter but returns in the spring. A sweet pea vine is herbaceous. Its tender vine dies, along with its flowers, and the plant will not return after the winter's frost.

Most garden flowers are herbaceous perennials. They die back to their roots but re-emerge in the spring or summer. Flowers such as asters, English daisies, blanket flower and lobelia are perennial. Most perennials live for three to six years, depending on the species and variety, as well as growing conditions.

To get an idea of the perennials in your region's growing conditions, take a trip to a botanical garden or university extension garden and view the plants growing in their perennial gardens.

Daffodils, crocuses, amaryllis and lilies return year after year much like perennials. Essentially, these plants are perennial, but because they die back to their bulbs during the winter, rather than to their root system, they are considered flowering bulbs -- a category distinct from perennials.

Some perennial plants bloom for as little as two weeks. Other may last longer, but overall perennials are not the showcase flowers that come to mind when you think of colorful summer gardens. Instead, you may think of bright petunias, hollyhocks and sunflowers. Vibrant annuals are usually purchased in bloom from nurseries and garden centers, although they can also be started from seed. They are planted throughout a garden to fill in spots left bare by faded perennials. Cool-season annuals are planted in spring and late summer, while hot-season annuals bloom through the summer.

Some annuals can be wintered over in warmer climates. Gardeners mulch the plants to protect them from an occasional frost, but the plants are able to withstand cooler temperatures. Horticulturists from North Carolina State University list pansies, larkspur and sweet alyssum among a number of hardy annuals.

Morning glories, zinnias and nasturtium drop seeds in the late summer. These seeds re-emerge in the spring. The benefit of self-seeding annuals is that they provide the color and vibrancy of annuals and the low-maintenance of perennials.

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