Perennial flowers live for several years when grown in the right conditions. In cold climates during the winter, perennials go through a period of dormancy, meaning the above ground parts of the plant die. However, the roots still live and grow, allowing the plant to produce new growth for the spring. In moderate climates, the above ground parts of the plant live all year long. The longevity of these flowers make them favorites among gardeners.
Hellebores bloom from winter to early spring and produce cup/saucer-shaped flowers in shades of green, pink, white and purple. They require full sunlight during the winter and shade in the summer. These perennials are vulnerable to black rot, leaf spot, mildew and slugs.
Day lilies (Hemerocallis)
Day lilies grow pale yellow, orange, red, pink or purple flowers that measure from 3 to 4 1/2 inches in diameter during early summer to fall. Each of these flowers stays open for only one day, but the day lily has many blooms to showcase for several weeks. These perennials prefer near neutral pH soil and full sun (with optional afternoon shade).
Bee Balm (Monarda didyma)
In full sun or light shade, tubular flowers of white, pink, red, lavender, blue or violet sprout from the bee balm in mid to late summer. This plant, which grows in cool climates, can suffer from mildew, rust, leaf spot and stem borers.
Goldenrods grow best in slightly alkaline soil and full sun but can tolerate light shade. Small but numerous yellow flowers bloom in late summer or fall and give the plant the look of fireworks or an exploding skyrocket. Contrary to popular belief, this perennial flower doesn't cause hay fever; ragweed, which grows at the same time as goldenrod, is the real culprit.
Large, daisy-like flowers in shades of red, pink, purple or white bloom from coneflowers from midsummer to fall. In the center, the flower is bristly and cone-shaped. These perennials like sun (with optional light shade) and can withstand dry climates but not leaf spot or Japanese beetles.
Other common and popular perennial flowers include the African lily, monkshood, Canna lily, summer daisy, common thrift, peony, Queen-of-the-prairie, daffodil, Virginia bluebell, spiderwort and prairie zinnia.