• Pampas grass is perennial grows up to 10 feet tall.pampas image by Hubert from Fotolia.com
  
  Any garden design will benefit from a selection of tall perennial plants. Tall plants create a strong visual backdrop at the rear of a flower border, when combined with shorter plants to the front. Tall perennials can play another useful role: disguising unsightly features in the garden. Perennial plants die back or become dormant at the end of the summer growing season, then burst into life again with the onset of spring.
  
  

Delphinium

• Not all varieties of delphiniums grow tall, but some will attain heights of six feet during the summer, blooming during July and August. The Iowa State University Extension recommends some varieties that will grow to 6 feet, including Black Knight with deep blue blooms, Galahad with white flowers and King Arthur, which produces violet blooms. The flowers grow on vertical spikes, each with many blooms, with some varieties producing single flowers and others double. Delphiniums favor full sun and a well-drained soil. To ensure strong flowering, delphiniums need regular feeding during the summer growing season. Use a general-purpose garden fertilizer, following the manufacturer's instructions.
  
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Pampas Grass

• Pampas grass grows in clumps and produces long stems topped by silvery to pinkish white feathery plumes, which in some varieties can be as tall as 10 feet. The plant grows best in full sun. Pampas grass will tolerate half-shade, but the blooms will be smaller. Harvest pampas grass blooms just as they mature to make attractive dried flowers. The plant is best cut back in winter when it can be pruned to the ground. The University of Georgia College of Agricultural and Environmental Sciences warns against growing pampas grass close to buildings as because of the fire risk from the dry, dead growth.
  
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Lilac

• Lilac
  
  Gardeners grow lilac for its attractive summer blooms with colors including, pink, white and purple. Cornell Cooperative Extension of Oneida County notes that late-blooming lilac hybrids such as 'Agnes Smith', 'Nellie Bean' and 'Miss Canada' may grow to a height of 25 feet or more. Lilacs are hardy plants, able to survive winters even in northern states and once established, only need watering in very dry conditions. They prefer well-drained soil with a pH value of 6.5 to 7 and grow best in full sun. Prune established plants after they have flowered to encourage growth and blooming in the following season.
  
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