© Janet Davis
All gardens benefit from unifying colors
that link disparate plants and colors that might otherwise clash. Plants with silver foliage accomplish that
task 
beautifully,
especially when paired with pinks, blues, purples, mauves and other analogous
hues. Yellows and reds also seem to
intensify a little more when placed beside or in front of silver foliage
plants.
“Foliage plant” is a misnomer, of course, since all plants flower. But many plants with silver foliage have flowers that are inconspicuous; this is often because silver leaves are an adaptive trait that help plants deal with unfavourable environments where showy flowers are a disadvantage. Artemisias, for example, are native to hot, arid prairies, mountains and deserts around the world; their flowers are small and yellowish. Lamb’s ears or woolly hedge nettle (Stachys byzantina) grows wild in Turkey and Iran Its foliage is “tomentose”, meaning “covered with short, dense hairs”, another adaptive quality that helps leaves conserve moisture and dew in dry regions (but dooms the plant to failure in high-rainfall areas where drainage is poor and water is trapped on the leaves). Flowers are purple, appearing along the tall, velvety, silver spikes. Though many gardeners remove the flower spikes, the blossoms are not large enough to distract from the overall silver effect desired in using lamb’s ears as a foliage plant.
When used in large swaths, as in the photo above (taken at a community garden in Philadelphia), silver- and gray-leafed plants have a restful, calming effect – quite different from the effect created using plants with gold leaves, which liven a garden up considerably. Many silver plants, such as artemesia, santolina and Russian sage, also have strongly aromatic foliage.
Here are several
annuals, perennials, shrubs and trees with silver, gray or blue-gray leaves:
Artemisia (Artemisia spp.) The wormwood clan is vast and varied and includes many with silvery foliage. Among the best for gardens in order of height are Artemisia schmidtiana, known as silver mound, (6 inches) which needs very well-drained soil; Artemisia pontica or Roman wormwood, 12-18 inches tall and twice as wide; Artemisia ludoviciana ‘Silver Queen’ and ‘Valerie Finnis’, both excellent for the mid-border at 24-30 inches (and a little less coarse than A. ludoviciana ‘Silver King’, pictured here); and common wormwood, Artemisia absinthium ‘Lambrook Silver’, at 30 inches, which should be trimmed in summer to keep it from flopping.
Blue Fescue:(Festuca glauca): A sweet little clump-forming grass that’s perfect for the front of a dry border, a rock garden, or a container in full sun. Grows to between 6-8 inches. Likes a little more moisture in full sun; drought-tolerant in light shade. ‘Elijah Blue’ is a good cultivar.
Blue Mist Bush (Caryopteris x clandonensis): One of the best “bee shrubs”, with its
spikes of lavender-blue flowers in late summer, blue mist bush (or bluebeard or blue spiraea, as it is sometimes
called) often dies down to its roots in winter in colder climates. Even if it does not, pruning it close to the
ground in early spring often generates more vigorous flowering. Grows 2-3 feet tall. Choose cultivars ‘Blue Mist’ for more
vibrant flower color, or ‘Dark Knight’ for dark blue flowers.
Blue Oat Grass (Helictotrichon sempervirens): At 20-24 inches in height, blue oat grass is perfect for use in the middle of the border. I’ve seen it interspersed with Gaura ‘Siskyou Pink’ in a way that makes the butterfly-like flowers of the gaura zing. I’ve also seen it used effectively in a small, jewel-like garden beside ruby-red New Guinea impatiens and ‘Red Baron’ blood grass. It’s also lovely with Russian sage and sedum ‘Autumn Joy’. Flower panicles are creamy-white and reach about 3 feet. Soil should be adequately moist, but very well-drained, especially in winter; drought-tolerant once established. Cut to the ground in late winter or early spring.
Dusty Miller ‘Colchester White’ (Centaurea cineraria): I’m not fond of common dusty miller – looks too much like an old-fashioned doily and doesn’t “blend in” with other annuals. But this big, new cultivar is really spectacular-looking with its feathery, exotic leaves, much like an artemisia. Grows 2-3 feet wide and tall, and loves heat and drought.
Dwarf Colorado Spruce (Picea pungens ssp. glauca cvs.): Most plants mentioned here are deciduous,
but there are a few conifers that lend their silvery-blue presence to the
winter months. None is richer in color
than the blue Colorado spruce. A giant
that might not be appropriate for smaller gardens, it has also given rise to
some attractive dwarf and semi-dwarf offspring. A ‘Fat Albert’ blue spruce will attain a mature height of 10-15
feet and grow in a stubby, conical shape almost as wide, making it a
substantial presence as a background plant in a mixed shrub-and-perennial
border.
Hosta (Hosta spp.): Though no hostas boast silvery leaves that would compare with the color of artemesias, there are numerous excellent, blue-gray (glaucous) hostas, from tiny to massive in size. Among the best are the old standby Hosta sieboldiana ‘Elegans’ (3 feet wide), ‘Blue Angel’ (4 ft.), ‘Halcyon’ (3 ft.), ‘Hadspen Heron’ (14 inches) and ‘Blue Skies’ (10 inches). Hostas perform best in moist, humus-enriched soil in part sun or shade.
Japanese Painted Fern (Athyrium niponicum ‘Pictum’): This lovely fern,
so well-named, does appear to have been conjured with a painter’s brush. Unusual for the fern clan, its fronds are
metallic silver edged in green with stems of dusky-purple. It loves partial to full shade (a great
bonus for a silvery plant) and grows 18-inches tall and up to 24-inches
wide. Japanese painted fern is a
stellar companion to other shade-lovers such as hosta, lamium, the shade grass Deschampsia
caespitosa and other ferns. But use
discretion when selecting its neighbors.
The intricate coloring of its fronds is so exquisite, it deserves to be
the prima donna, not second fiddle; avoid busy looking hostas and splashy
heuchera leaves.
Lamb’s Ears (Stachys byzantina): A sentimental favorite for many gardeners, the floppy leaves really do look like they might be attached to bunnies! The best cultivar is ‘Big Ears’ also known as ‘Helene Von Stein’). It forms a dense mat of silver leaves 4-6 inches from the ground. A great edger with other plants that like dry, alkaline soil, such as fragrant dianthus. Spreads quite aggressively by underground runners, but easily controlled by pulling out shoots.
Lavender Cotton (Santolina chamaecyparissus): Native to dry, sandy soil in the Mediterranean region, this plant is borderline hardy in Zone 6, where it benefits from a winter mulch, especially if snow cover is inconsistent. It features small, bright yellow summer flowers on 20-inch stems rising from silvery mounds of finely dissected leaves, so companion plants with yellow or white flowers create a pleasing vignette, as does Russian sage. Lavender cotton is often used to edge rose beds or knot gardens; in this case, the flowers are sometimes removed to achieve the geometric effect desired. Needs full sun, and dry, alkaline soil.
Licorice Plant (Helichrysum
petiolare): One of the best silver
annuals, this fuzzy-leafed trailing plant sends stems outwards in all
directions. Lovely with rich purples,
blues and pinks.
Russian Olive (Elaeagnus angustifolia): The best thing about Russian olive is the silvery color of its fine-textured leaves. Alas, its detractors claim that it is disease-prone; a noxious weed in warmer climates; and requires early pruning to lend it an attractive shape. However, it is ultra-hardy, drought-tolerant and a good choice for a tall silver accent where its 15-20 foot height works.
Russian Sage (Perovskia atriplicifolia): This is one of my favorite plants. I love the silvery-blue foliage so much that the long-lasting, lavender-blue flower spikes are a great bonus. Said to prefer sandy soil in full sun; however, in my country garden, the ones in humus-enriched sandy soil do much better than the ones planted in sandy soil “on the rock”. There are so many design possibilities for Russian sage, it’s difficult to narrow them down to a few. But plant it with tall Achillea filipendulina ‘Coronation Gold’ and native switch grass (Panicum virgatum), as I do, and you have a winner. I’ve also seen it used in brilliant pairings with tall, orange African marigolds, as well as with sedum ‘Autumn Joy’.
Silver Buffaloberry (Shepherdia argentea): This thorny prairie native shrub isn’t often seen in gardens, but its foliage deserves to be admired more widely. Small, leathery, silver leaves are deciduous. Its abundant, bright-red (sometimes orange or yellow), edible fruit adds another element to the color palette and make it a highly desirable bird shrub. Reaching a height of 6-10 feet at maturity, its shape is irregular, making it best for the back of informal borders, thickets or prairie plantings. Likes full sun and must have alkaline soil. In humid summers, it might develop leaf spot.
Silver Sage (Salvia argentea): Silver sage is a biennial that produces a 3-foot wide rosette of large, felted, silver leaves in its first summer, then tall stems with inconspicuous flowers in the second summer. As such, many gardeners either cut the flowering stems off or treat it as an annual, replacing it each year.
Weeping Silver Pear (Pyrus salicifolia ‘Pendula’): Often called “willow-leaf pear”, this small tree is elegant both in its graceful, weeping shape – lovely near a pond – and in the fine texture of the downy, silvery leaves. Though they tend to turn greener as summer wears on, the spring effect with the white flowers is delightful. Another excellent selection is ‘Silver Frost’. Unlike many of its silvery cousins, this one needs moist, well-drained soil.