In addition to providing color in the garden, perennials can also be used as solutions to problem spots in the home landscape. Many landscapes have hot, dry sites that are difficult for many perennials. Drought tolerant perennials are the perfect solution for these dry sites. Below is a list of some perennials that, once established in the garden, will tolerate or even thrive in dry conditions.
Fernleaf Yarrow (Achillea filipendulina) is a medium-sized perennial that grows approximately 3 to 4 feet tall with a 3 foot spread. This perennial has silver-gray, fern-like foliage and large, flat, yellow blooms in late spring to mid-summer. The blooms can be used for cut and dried flowers. Dried heads will retain color best if the flowers are cut before pollen has developed. Yarrow prefers conditions with full sun and dry soil. Popular cultivars include 'Coronation Gold' which is 3 feet tall and has bright golden flowers and 'Moonshine' which is 2 feet tall and has bright yellow flowers.
Artemisias are a large group of perennials with silvery-gray foliage and a high tolerance to hot, dry conditions. This perennial is grown mainly for its foliage, although some types produce small, ineffective flowers in summer. Artemisias are often used as a filler or as a complement to the pinks, lavenders, blues, yellows, and reds used in the garden. 'Silver King' is a common variety with a height of 2 to 3 feet and a wide, spreading clump form. This variety can be aggressive and needs to be divided every two years. The foliage is excellent for cut and dry usage. 'Silver Mound' is another widely grown variety. It is 12 to 18 inches tall and forms a mound 18 inches in diameter. The foliage is very silky and lacy. This variety is less aggressive and may be used as a border or in rock gardens.
To provide early summer bloom, Centaurea montana, or Perennial Bachelor's Button (right) may be incorporated into the garden. The foliage is spear-like and gray-green in color. Younger leaves are silvery-white. Black, fringed bracts occur beneath the solitary blue flowers. This plant prefers full sun to part shade and well-drained soils. Perennial Bachelor's Button possesses good drought tolerance. For the best effect, this species should be massed. Centaurea can be very invasive and should be divided every two years. Cultivars include 'Alba' which has white flowers, 'Carnea' which has pink flowers, and 'Violetta' which has dark violet flowers.
Threadleaf Coreopsis (Coreopsis verticillata) provides a light, finely textured addition to the perennial garden. This perennial blooms late spring through late summer. It grows best in a dry, full sun situation. Coreopsis works well in the perennial garden or naturalized area. 'Moonbeam' has creamy-yellow flowers. The plant is 18 to 24 inches tall with lacy foliage. This cultivar was selected as the 1992 Perennial Plant of the Year by the Perennial Plant Association. 'Zagreb' is another popular variety with bright yellow flowers on a 12-to 18-inch-tall plant.
Purple Coneflower (Echinacea purpurea) (left) is a native plant to Iowa and excellent for wildflower gardens and naturalized locations. This plant possesses coarse foliage and grows to 2 to 4 feet tall and 2 feet wide. The flower heads consist of purple, or sometimes white, ray flowers and brown, cone-shaped disk flowers. The "petals" or ray flowers typically droop. Purple coneflower blooms in summer and prefers full sun and well-drained soils. The flowers can be used for cuts. Gold finches love the seeds produced in the central cones. 'Alba' is a popular white cultivar. 'Magnus' produces rosy-purple flowers with non-drooping petals. 'Magnus' was selected as the 1998 Perennial Plant of the Year by the Perennial Plant Association.
Ozark Sundrop (Oenothera missouriensis) (right) has a trailing habit which makes it an excellent choice for the raised bed, rock garden, or edging of perennial beds. The foliage is dark green with a white midrib. Large, 3-to 4-inch-wide, canary yellow flowers appear in summer followed by four-winged, torpedo-like fruits. Ozark Sundrop prefers full sun and a well-drained soil and is tolerant of poor soils and drought conditions.
For a late summer bloom, try Russian Sage (Perovskia atriplicifolia). The foliage is aromatic, finely dissected, and gray-white in color. This plant has an upright growth habit with a height and spread of 3 to 4 feet. The lavender-blue flowers appear on a spike that extends above the foliage. Russian sage grows well in full sun and well-drained soils. For the best growth and flowers, Russian sage should be cut back to within several inches of the ground in the spring. In addition, Russian sage should be protected for the first couple of winters after planting. This plant can be used as a filler in the perennial garden, and the gray stems provide winter interest. Popular cultivars include 'Blue Spire' and 'Longin'.
Other perennials that are tolerant of dry soils include the following:
|Anthemis tinctoria||Golden Marguerite|
|Arabis caucasica||Rock Cress|
|Asclepias tuberosa||Butterfly Weed|
|Echinops ritro||Globe Thistle|
|Eryngium sp.||Sea Holly|
|Gaillardia sp.||Blanket Flower|
|Liatris sp.||Gayfeather, Blazing Star|
|Malva alcea||Hollyhock Mallow|
|Phlox subulata||Moss Phlox|
|Physostegia virginiana||Obedient Plant|
|Rudbeckia sp.||Black-eyed Susan|
|Stachys byzantina||Lamb's Ear|
|Thymus sp.||Garden Thyme|
This article originally appeared in the May 22, 1998 issue, pp. 62-63.