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Very Tall Perennial Flowers

Tall perennial flowers can give a garden a stately appearance. Use them as borders and backdrops in your flower garden, as freshly-cut flowers on flower arrangements for your home, or for wedding ceremonies or banquets. Drying tall perennial flowers are ideal for making dried flower arrangements or potpourri.

Delphinium Black Knight

Also known as Delphinium Black Knight, delphinium flowers grow 5 to 6 feet tall. Elatums, belladonnas and Pacific hybrids are the three types of delphinium. Delphinium Black Knight belongs to the elatum group, which predominantly grows in Zone 4. Delphiniums are clump-forming plants that produce intense blue flower spikes, which bloom from June to July. Delphinium Black Knight prefers full sun and well-drained, compost-rich soil. Feed delphiniums monthly with a balanced liquid fertilizer. Staking delphiniums is necessary to avoid drooping or breaking. Delphiniums can become woody as they age; therefore, it is advisable to replace them every three to four years. Encourage flowers to bloom in the fall by cutting the plant back after the initial flowering. Delphiniums can survive the high altitude and are ideal for cutting. Using Delphiniums in a flower arrangement can add height and visual interest. Most delphinium plants are poisonous, so take precautionary measures when planting in a garden frequented by children and animals.


An agastache is a tall perennial flower that is very aromatic. Rubbing the coarse leaves of the agastache plant produces a minty smell with a hint of licorice and citrus. Agastache produces lavender-blue flower spikes from mid- to late summer. Filled with nectar, agastache's blooms appeal to bees, butterflies and hummingbirds. Agastache prefers full sun to partial shade and well-drained soil. Growing as high as 24 to 36 inches tall, agastache is an excellent backdrop for a flower bed or border. Agastache is native to the southwestern United States and northern Mexico. This plant also can be found across the United States, Europe and Asia. Poor air circulation and high-humidity can cause powdery mildew, rust and fungi on the agastache leaves. Deadheading wilted flowers and pruning the dead branches will encourage more flowers next blooming season.


Also known as baptisia australis or wild indigo, a baptisa plant can grow up to 7 feet high or more. Baptisa is native to North America and has an upright, shrubby form with slim stalks that have blooms in blue, white or yellow. Considered hardy perennials, baptisa blooms in late spring or early fall in zones 3 to 10. Plant baptisa under full or partial sun and in a well-drained soil with a pH of 5.5 to 7. The blossoms start as plump, tight, pea-like buds. The flowers appear as vivid blue with yellow or creamy flecks. The appearance of seed buds makes baptisa a member of the pea family. The seed pods turn black over time. The flower, seed pods and leaves of baptisa plants are virtually free from pests and diseases.

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