Silver or gray is an interesting color in the landscape. Similar to white, silver has the ability to soothe and blend with other colors. Yet unlike white, metallic colors often contrast or stand out in green landscapes. Visualize how Colorado Blue Spruce (Picea) or Dusty Miller (Cineraria) shine in their surroundings. There are many perennials that have the same ability to "sparkle" in your garden. As an added benefit, many silver foliage plants prefer full sun with dry soils making them excellent "summer-tolerant" performers in the garden.
Lamb's ear (Stachys byzantina) is one of the most recognizable of silver foliage perennials. The whitish hairs that cover each leaf give the plant a soft covering and gray appearance. This perennial groundcover is grown primarily for its foliage. The cultivar 'Silver Carpet' is noted for its consistent silver coloring, low-growing habit (12 inches), and lack of flowers.
Another group of perennials that are grown primarily for foliage are the Artemisias. Louisiana Artemisia (Artemsia ludoviciana) grows to 3 feet tall and often spreads quickly in the garden. The wooly gray foliage on long stems dries well and is often used in flower arrangements. In contrast, 'Silver Mound' Artemisia (A. schmidtiana) grows 15 inches tall and remains in clumps. Its foliage is finely dissected and delicate in comparison to Louisiana Artemisia. Both artemisias flower in late summer, but the whitish-yellow flowers are often of little consequence.
The lavender-blue flowers on Russian Sage (Perovskia atriplicifolia) are one of its most ornamental features. In late summer the flowers compliment the gray, aromatic foliage. Plants grow 4 feet tall and 3 feet wide. If allowed to remain, the silvery stems and leaves will stand in the garden through much of the winter.
Another groundcover perennial with metallic foliage is Snow-in-Summer or Cerastium tomentosum. This 6 to 8 inch-tall plant has bright, white flowers that cover the small silvery leaves in May. Snow-in-Summer is ideally suited for pockets in rock walls or other dry sites. However, it is not tolerant of long periods of summer heat and humidity.
There are several Ornamental Mullein (Verbascum) varieties that are ideally suited to almost any sunny, dry situation. The pubescent basal foliage resembles lamb's ear. Yet, this biennial is noted for its attractive white, yellow, pink, or peach spire-like flowers in early summer. Unfortunately because they are biennial, many are short-lived.
Another biennial with silver foliage is Rose Campion (Lychnis coronaria). Rose Campion has showy rose, white, or red flowers that contrast with the silver-green leaves. Flowers are produced profusely in summer on open, airy plants that are 2 to 3 feet tall. Plants often reseed assuring their place in the garden for several years.
Other sun-loving perennials with silver foliage include: Yarrow (Achellia 'Coronation Gold'), Butterfly Bush (Buddleia davidiana), and Wooly Thyme (Thymus). In addition, there are a few shade-loving perennials with silver foliage markings. Perennials such as Lungworts (Pulmonaria saccharata), Yellow Archangle (Lamiastrum), and Heartleaf Brunnera (Brunnera macrophylla 'Langtrees' and 'Jack Frost') can brighten darker corners of the landscape with their silver foliage.
This article originally appeared in the July 26, 2002 issue, pp. 105-106.