Whether you want to create a dramatic look or don't have a lot of horizontal space to work with, upright and climbing perennials add vertical interest to the garden. Perennials at least 4 feet tall draw the eye upward, creating an elegant, bold look, while climbing vines make good use of vertical space on fences and walls. When planning your perennial bed design, place the tallest flowers at the back of the bed, then graduate shorter plants toward the front of the bed.
1. Spring Color
For bright yellow flowers from May through late summer, plant verbascum (Verbascum pyramidatum). Reaching heights of 7 feet, this perennial blooms with spires of yellow blossoms with purple centers. Verbascum thrives in sunny, well-draining sites in U.S. Department of Agriculture plant hardiness zones 4 to 8. Goat's beard (Aruncus dioicus) grows to 6 feet tall and fills the late spring garden with airy, cream-colored sprays of flowers. After it flowers, goat's beard adds interest and texture with its dark foliage. This North American native grows best in rich, moist soil and partial shade in USDA zones 4 to 8.
2. Summer Color
Bear's breeches (Acanthus spinosus) blooms in midsummer with spikes of blue and white flowers atop 4-foot-tall stems. This upright perennial adds more vertical interest with its spiny foliage. Plant bear's breeches in partially shaded, well-draining sites in USDA zones 7 to 10. New Zealand flax (Phormium tenax), an ornamental grass, grows in a 10-foot-tall clump of bronze-brown or striped white, pink and green foliage. In summer, it blooms with red inflorescences atop 12-foot-tall stalks. Plant the New Zealand flax in rich, moist soil in USDA zones 9 to 11.
3. Fall Color
For bright yellow-gold fall color, plant sunflowers (Helianthus spp.). These cheerful perennials grow to 7 feet tall and some bear edible seeds. Plant sunflowers in sunny, moist sites in USDA zones 6 to 9. Plant the climbing Carolina aster (Ampelaster carolinianus) against a supportive trellis, wall or fence and enjoy fragrant, pale purple flowers through fall. This perennial vine climbs to 15 feet tall and thrives in sunny sites with moist soil. It grows in USDA zones 4 to 8.
4. Long-Lasting Color
Hollyhocks (Alcea rosea) bloom from spring through fall with showy flowers in a range of colors, from yellow to pink, atop tall stalks. These perennials grow to 5 feet tall and grow in USDA zones 5 to 9. They grow best in sunny, well-draining sites. The Brazilian verbena (Verbena bonariensis) grows to 4 feet tall and blooms with purple flowers from summer through frost. Hardy in USDA zones 7 to 9, this upright perennial thrives in sunny spots and attracts butterflies and bees to the garden.
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