What is the difference between annual flowers and perennial flowers?
Annual plants complete their life-cycle in one growing season. Familiar annuals include Petunias, Marigolds, Impatiens, Million Bells, and most of the showy, long blooming plants that we use in our hanging baskets and patio containers. Because they live for only one season, annuals put all of their energy into producing abundant flowers from spring through fall. Annual plants must be planted each spring (“annually”).
Biennials are plants that complete their life cycle in two years. The first year they produce only foliage, usually low to the ground. In their second year of life they grow to their full height, bloom and produce seeds. If allowed to self-sow these plants will produce seedlings and persist in your garden from year to year. Since seedlings will decide for themselves where to grow and might not come up exactly where the gardener desires, biennials are best suited to a cottage garden or informal flower bed. Familiar biennials include Hollyhocks and Foxglove.
Perennials are plants that survive in the garden for multiple years. Some live for decades while others may live only 3-5 years. Because perennials need to devote energy to root development, they cannot use all of their energy on flowers and therefore bloom for a shorter time than annuals. Most perennial bloom for 3-4 weeks but some particularly long blooming ones may provide as much as 8-10 weeks of flower color. Familiar perennials include Peonies, Daylilies, Hosta, Iris, and Coneflowers.
Trees and shrubs live for more than two years. Are they perennials?
Technically speaking, trees and shrubs are perennial plants — they grow for more than two years. But we categorize perennial plants into two types: woody plants and herbaceous perennials. Woody plants are trees, shrubs, and vines whose above-ground parts persist over the winter, and resume growth in the spring. Herbaceous perennials are non-woody plants that die back to the ground each fall. The roots, however, survive the winter and the plants re-sprout in the spring.
Why grow perennials instead of, say, a bed of annual petunias, marigolds, or impatiens?
If you grow lots of annual flowers, you are familiar with the annual chores necessary to maintain such beds: you purchase flower seedlings (or start your own), and plant them. You nurture them throughout the growing season, fertilize and water them; then, when the season’s over and the plants die, you pull them out. Next year, the cycle begins anew.
Perennial plants remain in the ground year after year. Once established, many perennials need minimal upkeep in the form of watering and fertilizing, since their roots are more far-ranging than annual plants’ roots. Many perennials spread readily, filling out garden spaces and providing more and more color each year.