Perennial plants need be planted only once and then continue blooming for several years. According to North Carolina State University Extension, "the term perennial is frequently used by gardeners to refer to herbaceous perennial flowers." When planted correctly, it's possible to have perennials in bloom throughout each season. With their colorful blooms and unusual foliage, they provide interest to the garden for a showy display.
White coneflower (Echinacea purpurea "White Swan") is a perennial flower with a moderate growth rate and upright, clumping habit. The white, daisy-like flowers grow up to 4 ½ inches long to surround the copper to green central cones. Emerging in early summer, white coneflowers continue blooming until early fall, creating a long flowering season. White coneflower cones attract butterflies and birds to the garden to eat the seeds within. Drought-tolerant, white coneflowers have erect, tall stems and green bushy foliage. Growing one to three feet tall and wide, white coneflowers are ideal plants to grow along a flowerbed border or lining a garden walkway. They grow best in full sun to part shade and well-drained, deep soil. They are tolerate of poor soils, heat and humidity, creating a versatile outdoor blooming perennial plant variety. To promote a long flowering season, pinch off the dead blooms as soon as they are visible. Plant white coneflowers in U.S. Department of Agriculture (USDA) Hardiness Zones 3 to 9.
Hollyhock (Alcea rosea) is a perennial flower with funnel-shaped blooms that grow on tall, erect spikes to form a clumping growth. Growing six to 10 feet tall and one to three feet wide, hollyhock flowerheads grow in a wide range of colors including red, peach, yellow, white and purple. Blooming in early to midsummer, hollyhock flowers have a moderate growth rate. Lining the back of a bed or border, hollyhock creates a commanding backdrop to the garden. Hollyhock flowers require full sun and well-drained, nutrient-rich soils to thrive. They grow best in average to dry soil. Plant in USDA zone 4.
Coral bells (Heuchera sanguinea) are a perennial ground cover that grows in upright clumps from May to June. Growing one to 1 ½ feet tall and up to one foot wide, the small flowers on coral bells grow in narrow, upright panicles of bright red flowers that appear to be shooting out of the foliage. The foliage is heart-shaped to round and appears in low-growing mounds. Coral bells require full sun to part shade and well-drained, nutrient-laden soil. To ensure a long blooming season, cut back the spent blooms. Plant in USDA zones 3 to 9.