There are so many hues of blue, gray and silver that they are difficult to match, so utilize subtle changes in foliage color or texture instead for contrast. Try using plants such as yucca or euphorbia as sculptural elements. Variations in leaf color occur as variegations in pigment, or color can be perceived as silver, blue or gray because of downy or waxy coatings on leaves.
Below is a sampling of plants that offer a blue, gray or silver appearance and are excellent accents for rose gardens.
Wormwood (Artemesia) offers many species. Grown mostly for its fragrant, woolly, silver/white foliage, its flowers are insignificant. It’s showiest in summer when growing in full sun and sandy, well-drained soil, tolerating drought. Use in masses or borders.
Culinary sage (Salvia officinalis) is most often used for cooking. It has ornamental, fragrant blue foliage with dainty violet-blue flowers, is drought-tolerant, and does best in full or partial sun with well-drained soil. It attracts butterflies and hummingbirds and makes a good cut flower.
Lamb’s ears (Stachys byzantina) flowers in spring and has woolly foliage that’s soft and grows with a loose-mounded habit. It’s drought-tolerant and requires moist soil that must be well drained. Remove yellow flower spikes as they develop, because they detract from the ornamental value of the foliage.
Russian sage (Perovskia atriplicifolia) flowers mid-summer to early fall with striking violet-blue flower spikes against silvery-green foliage that exude a sage-like fragrance. It prefers a sunny location, excellent drainage and is drought-tolerant. Cut back in late spring to encourage fuller plants. This vigorous perennial will grow 36 to 48 inches tall.
Catmint (Nepeta faassenii) foliage ranges from blue-gray to gray-green depending on the hybrid. Porcelain is a cultivar that is especially handsome, with blue leaves and blue flowers that persist most of the summer. This fast-growing herb will grow two feet high and spread if sited in full to partial sun with moist, well-drained soil. Prune old flower heads to encourage new blooms. Its aromatic foliage is especially attractive to cats.
Colorado blue spruce (Picea pungens) is a conifer with needles that can be almost phosphorescent blue on specimen-quality trees. This pyramidal evergreen with green to silver-blue foliage likes sun and moist, well-drained soil and is deer-resistant. Its ultimate size over 35 years is 60-feet tall by 25-feet wide.
Blue star juniper (Juniperus squamata) is an evergreen with sharp needles. It’s a low, compact, dense and mounding shrub with a slow growth rate that’s drought-tolerant and prefers full sun, reaching three feet in height and width. Mature foliage is silver blue and new foliage is a rich blue.
Elijah blue fescue (Festuca glauca) is a low-growing, porcupine-like, dome-shaped tufted grass with fine, silvery blue foliage. Plant in moist, well-drained soil and in full sun. It tolerates light shade, drought and poor soils but not “wet feet.” Handsome designed as a groundcover or edging, or used in a container. Cut back in early spring to three to four inches to encourage new growth.
Lavender (Lavandula angustifolia) has semi-evergreen foliage, deep blue flowers in summer and is attractive for its silvery-green needle-like foliage and fragrant lavender flowers throughout summer. It attracts butterflies, likes sunny locations and excellent drainage, and is drought-tolerant. Grows 12 to 24 inches tall, including flower spikes. Lavandula angustifolia and L.
x intermedia are considered two of the hardiest lavenders. The top consideration for using lavender is having excellent drainage. If clay soil is a problem, plants benefit from pulverized horticultural limestone added to the soil. They flower best in full sun. Lavender can be designed to edge a rose bed or placed in openings among the roses. It depends on whether you want a formal or informal design.
Baths pink dianthus (D.
gratianopolitanus) makes an evergreen blue mat with fragrant pink flowers in spring. Performs well as a drought-tolerant groundcover in full sun. Its long-blooming, abundant, spicy-scented flowers will grow 6 to 12 inches high and can reach three feet wide or more. Plant in moist, well-drained soil in sun to partial shade. Deadhead to encourage more blooms and make the foliage cleaner. Use along walkways, paths and borders. Also makes an excellent groundcover around roses. Cold-tolerant, heat-resistant and seldom damaged by deer.
Pewter veil coral bells (Heuchera americana) have creamy white flowers. This perennial’s leaves emerge pinkish copper then turn metallic silver with purplish-blue undertones. It will grow one to two feet tall and 12 to 18 inches wide. Flowers are excellent for cutting. Remove stems of faded flowers to encourage more blooms. Place in full sun to partial shade, and in moist, well-drained, humus-rich soil. If planted in full sun, needs constant moisture. Is an excellent complement to rose gardens.
Japanese painted fern (Athyrium nipponicum) is a deciduous perennial fern with silvery, blue-gray leaves growing on maroon stalks. The almost metallic foliage appears painted. Grows 18 inches and forms dense, pest-resistant colonies. Plant in neutral to slightly acidic humus-rich soil. Use in groupings and along edges of rose gardens.
Joel M. Lerner is president of Environmental Design in Capitol View Park, Md.