7 Sensational Silver Plants - Mother Earth Living

Taken from Elegant Silvers: Striking Plants for Every Garden©2005 by Jo Ann Gardner and Karen Bussolini. All photos in the book ©2005 by Karen Bussolini. Published by Timber Press, Portland, OR. Used by permission of the publisher. All rights reserved.

Agave (Agave spp.)
Artemisia (Artemisia spp.)
Butterfly Bush (Buddleja spp.)
Heather (Calluna vulgaris)
Lavender (Lavandula spp.)
Sage (Salvia spp.)
Russian Sage (Perovskia spp.)

Whether designing a landscape from scratch or reworking a section of a perennial garden, most gardeners can’t wait to start acquiring new plants. Walking through the gardens, snipping and digging, touching, smelling, noticing the surprises and delights of our plants is the joyful heart of gardening. Plants with similar characteristics tend to harmonize with each other, creating a sense of tranquility. The contrast of plants that are very different from each other adds zing. Paying attention to the characteristics of our favorite plants—color, shape, sheen, habit, texture and other qualities—helps us predict how they will work in combination with plants that have similar or different characteristics.

We started not with a theory of color and design but with muddling around in our own gardens, combining plants until they “felt right.” We learned that compiling a bouquet while strolling through the garden with snippers or walking a plant around the nursery to see how it looks with other plants inspires unanticipated combinations. Serendipitous self-sowers instructed us by making felicitous combinations on their own.

The Art of Combining Silver Plants

Copying directly from other gardens is certainly fair game, but often it’s the ideas, not the plants themselves, that take root in our own gardens. Liking the lovely tension between cool, bright Artemisia ludoviciana ‘Silver King’ and the chartreuse zinnias and nicotiana we saw flowering in the sun at the Berkshire Botanical Garden, for instance, inspired us to pair chartreuse-flowering Alchemilla mollis with the gleaming silver blades of Pulmonaria ‘Excalibur’ in a shady spot. Wiry, nodding native delphiniums weaving their way up through bold, spiny-tipped Zone 8 yuccas in a Texas garden suggested contrasts with our own hardy Yucca filamentosa. Once we realize that we like a certain kind of combination—warm with cool or bold with delicate—we can extrapolate to other kinds of plants that will grow happily in our own gardens.

Color

Color is often what we notice first. It sets the emotional tone of a garden. We are excited by flamboyant color combinations or soothed by subtle ones. Yet color is the most personal of choices. One person’s subtle seems dull to another, vibrant crosses the line to tacky for some and classic may seem tired.

Silver at its purest is not a color at all but the very essence of light. It is the chameleon of the plant kingdom, changing with light and season, hard to put your finger on. Silver can be retiring background or the star of the show, garish or subtle, soothing or distinctly exciting. Some silvers are stunning on their own—an avenue of poplars, a solitary shimmering eucalyptus, a helichrysum topiary. Silver plants have a unique ability to intensify other colors or to knit them together (sometimes at the same time). It is in relationship to other plants, whether blending or contrasting, that silvers, finding their strength, truly shine.

Silver as Peacekeeper

On a hot day, the shade of a silver tree seems cooler than the shade from other trees. A silver passage in the garden provides respite. The many shades of silver, from gray-green to gray, pewter, bright silver or silver-blue, blend well with each other because of their shared tonal qualities. Silver gives white flowers a context that saves them from washing out in the sun. Silvers and grays have a special sympathy with pastel-colored flowers and the washed-out earth tones of plants such as New Zealand sedges. A drift of silver can buffer clashing colors, helping them blend together and giving our eyes a rest.

Some silver plants seem to look good with everything. We have seen Russian sage (Perovskia atriplicifolia), lamb’s ears (Stachys byzantina ‘Helene von Stein’), blue oat grass (Helictotrichon sempervirens) and Nepeta ×faassenii ‘Six Hills Giant’ keeping the peace in gardens all over the United States. In a Connecticut garden, the nepeta edging a long allée knits together all the hues and tangle of a rose garden. In Minnesota, bright perennials are unified when displayed against a shimmering ribbon of spiky blue Helictotrichon, Panicum virgatum ‘Heavy Metal’ and Perovskia. In our own garden, Stachys byzantina ‘Helene von Stein’, with sparse silver hairs on gray-green leaves, is a fine bridge between plants on the green side and bright silvers. We suspect that whatever riot of color a garden might possess, a good dose of any of these four plants, or any number of silver substitutes, would make sense of the chaos.

Silver Contrasts

Peace in the garden is fine up to a point, but a garden that only blends and never contrasts gets dull. For gardeners seeking drama, pairing any of silver’s tonal qualities with their opposite qualities creates excitement. If a silver is bright and light, try a dark companion. Silver and gold is another case of opposites attracting. Many silver plants—notably the senecios, helichrysums, achilleas and santolinas—have yellow flowers, providing built-in warm contrast. The possibilities for dynamic combinations seem endless. If silver is cool, turn up the heat by pairing it with warm reds, russets and oranges. If it is a dull gray, create a glow with more brilliant tones. If it is a clear, simple tone, surround it with complex or muted neighbors with purple-green leaves or mauve flowers. If it is on the blue side, pair it with oranges or yellows across the color wheel.

Texture

Combining plants with textures that are alike or different adds another dimension to garden vignettes. Texture is created by size and shape of leaves and by the feel or appearance of the leaves’ surfaces. The lobed fans, deeply cut lace, or tiny, softly curling tendrils of artemisias contrast with linear grasses and with the round leaves of eucalyptus. It is difficult to appreciate the virtues of the many small-leafed nepetas, lavenders, origanums, helichrysum and santolinas when they are all jumbled together, as they often are in herb gardens. These plants might not contrast with each other, but their petite leaves make for big contrasts with Verbascum bombyciferum, agaves, yuccas and other large-leaved plants. Contrasting the many surface textures of silvers—shiny, dull, fuzzy, pebbled, soft, hard, leathery, downy, powdery, smooth and waxy—suggests many ways to enrich our combinations.

Form

Paying attention to growing habit and silhouette (upright, laterally branching, curving, swirling, weeping, waving, mound, mat, or spiky vase-shaped) gives us additional opportunities to make exciting garden pictures. A few silver plants—Scottish thistles, artichokes and agaves—are so boldly architectural that they make striking contrasts with just about everything. Try juxtaposing spiky grasses with low scrambling, round-leaved plants; soft, low mounds with taller, more upright plants; or a hard architectural form with a frothy, indistinct outline.

Dynamic Combinations: Alike but Different

Color, texture and form do not exist in isolation. They interact—or fail to—all at once. The more ways they interact, the more satisfying the combination. A simple combination of lamb’s ears and cushion spurge works exceptionally well, not just because it contrasts gold and silver, warm and cool, but because the spurge’s rounded flower heads and bracts, small and smooth leaves arranged on upright stalks, smooth surface and modulated hues are strikingly different from the lamb’s ears’ mat of much larger, blade-like leaves, very fuzzy texture and uniform color.

In a container planting of Begonia ‘Looking Glass’ and elephant ears (Colocasia esculenta ‘Black Magic’), we can see that although the leaves have a similar shape, the elephant ears are much bigger. Leaves have a similar texture, but the begonia’s surface sparkles in sunlight, while the elephant ears remain dull. Major veins of both are green, but begonia is silver on the front and red on the back, shimmering and light in comparison to the dark, almost black, elephant ears. The plants’ similarities are close and their differences extreme, adding up to a complex, resonant picture.

A History of Silvers

The silvers we admire today for their beauty were once regarded solely as useful plants, praised for their ability to cure or alleviate a wide variety of human complaints, from toothache to the pangs of childbirth. Classic silvers—artemisia, lavender, rue and sage—once were no more than familiar drugs in the ancient pharmacopoeia or drugstore. The fact that their leaves were downy or glaucous, a departure from normal green, did not create an aura of suspicion around them, as was the case with other plant oddities such as mandrake, whose bizarre-shaped roots earned it a reputation as a dangerous magical force to be approached with caution. On the contrary, no fear was attached to using the ruffled, gray-green horehound to soothe a cough or silvery gray wormwood as a cure for stomach complaints. These were common plants—despite their unusual appearance—and a familiar part of everyday life. True, lavender was an ancient symbol of mistrust, but this association was based on the plant’s sharp scent rather than its silvery leaves.

Agave

Agave spp.
Common name: century plant, woody lily
Family: Agavaceae, agave
Description: waxy succulent perennial
Origin: Americas
Site and soil: sun to shade; sharply drained
Height and width: 1.5 to 10 feet tall; 2.5 to 10 feet wide
Hardiness: Zones 5 to 10

Agaves are striking plants found in every possible climatic niche, from dry tropical coastal zones to alpine forest conditions where they are subject to moisture and snow. The silvery agaves originate in the American Southwest and Mexico, where they epitomize the landscape. Rosettes of rigid, fleshy, swordlike leaves, from narrow to wide, pointed and arching or perfectly rounded, are sleek and smooth or textured. Many have toothed margins, some with spines and vicious leaf tips with an elongated point that is fearsome in some species. Silvery agaves range in color from gray to powder-blue and their forms vary from relatively small to monumental, from 12 inches to 20 feet across, with flowering spikes up to 40 feet in the air. Lilylike flowers, pollinated by bats, moths or hummingbirds (depending on their type), bloom in terminal umbel-like clusters, racemes or panicles on leafless stems. The genus name from the Greek agavos means noble, a reference to this spectacle, while the common name (century plant) is based on the monocarpic habit of many agaves to flower infrequently—but it is misleading. Smaller species are faster-growing and may bloom when they are 3 or 4 years old; slower-growing, larger types may take 40 to 50 years to bloom, but not a century. Agaves flower only once and the plants die but leave progeny (offsets or pups) behind.

For millennia, agaves have sustained native people with food, fiber, drink and medicinal preparations. The commercial and illegal overharvesting of agaves has led to concerns about the destruction of their habitat. Natural variations among species result in taxonomic uncertainty—apparently identical plants may have different names.

Artemisia

Artemisia spp.
Common name: wormwood, sage brush
Family: Asteraceae, aster
Description: downy perennial, subshrub, shrub
Origin: deserts, dry fields, mountains, steppes; Northern Hemisphere, South Africa, western South America
Site and soil: sun; dry, well-drained
Height and width: 5 inches to 4 feet tall; 12 inches to 4 feet wide
Hardiness: Zones 3 to 10

Named for the goddess Artemis, the genus is dominated by subshrubs, many evergreen or nearly evergreen. As plants with a long history of use as medicinals to treat a variety of complaints, they have always been represented in herb gardens. Gardeners value them for their beautifully cut foliage in the sterling to gray range, versatility of forms from ground-hugging to tall shrubs, and dependability. Bitter properties, present to some degree in all artemisias, are due to the chemical thujone, which gives them their characteristic bracing aroma and medicinal value as a vermifuge. Some have an important place in Traditional Chinese Medicine, and many are choice for crafts (especially wreaths).

When purchasing artemisias, do be aware that taxonomic confusion abounds among artemisias: species are shifted around, plants are sold under names that have no botanical standing and plants with the same names may bear little resemblance to one another (while plants with different names appear very much alike!).

Butterfly Bush

Buddleja spp.
Common name: butterfly bush
Family: Buddlejaceae, butterfly
Description: downy shrub
Origin: riversides, rocky areas and scrub; Asia, Southwestern United States
Site and soil: sun; fertile, well-drained
Height: 3 to 20 feet tall; 4 to 15 feet wide
Hardiness: Zones 4 or 5 to 10

These old-fashioned shrubs are favored for their long, fragrant flower trusses so attractive to butterflies; their tolerance for drought condition; and their ability to grow up to 6 feet and just as wide in a single season from their roots. They are enjoying a renaissance of interest with the introduction of more compact, less weedy forms and a color range beyond the ordinary lilac-purple, including dark purple, reddish, blue and pink flowers. For the silver fancier, there is the added allure of types with intensely silvery leaves, a coloration that heretofore has been merely suggested in silver-backed foliage. The bush’s form is wide and arching, loosely and irregularly vase-shaped, or compact in the newer dwarf types. (In butterfly bush parlance, the term “dwarf” is relative, since some of these may grow up to 6 feet tall.) Flowers of the Asian species discussed here are small and tubular, carried in dense pyramidal or conical heads, sweetly scented like honey and sometimes marked with a darker eye. Leaves are often lance-shaped and willowy, dully green above and silvery below. In some types, leaves appear entirely silver in their early growth. Named for an English botanist, Adam Buddle, the Latin genus is spelled with a j as in Buddleja, but the common name form is spelled buddleia. You will find both spellings in the trade.

In climates with colder winters, buddleias may die back to the ground in the same way as an herbaceous perennial, but they are fast growing and will come back from their roots amazingly fast when warm weather sets in to produce flowers by midsummer to late summer on full-grown bushes. Early-flowering bushes like Buddleja alternifolia, which produces flowers on previous year’s growth, are thinned out after flowering and then pruned hard after frost. Later flowering types such as B. davidii, which produces flowers on the current year’s growth, are pruned back about 12 inches or more just as new growth begins. If stems are left to 2 to 3 feet, bushes will bloom about the same time as if they were hard-pruned, but hard-pruning has the advantage of keeping bushes shorter and more compact. Even in warmer regions, where shrubs do not die back, they should be hard-pruned to maintain a dense shape.

Heather

Calluna vulgaris
Common name: heather
Family: Ericaceae, heath
Description: downy shrub
Origin: moors, lowlands; Europe, Asia Minor
Site and soil: sun; acid, well-drained
Height and width: 6 to 24 inches tall; 12 to 14 inches wide
Hardiness: Zones 4 to 8

In heather’s natural range it grows as a spreading cover over miles of otherwise barren ground and in highland and lowland habitats. It provides food and cover for grouse, deer, smaller mammals, reptiles and insects. Long recognized for its beauty, poets have sung its praise and ordinary people have turned it to practical use. The genus name, based on the Latin kalluno (to clean), refers to heather’s use as a broom or brush. Growing on unused or discarded land, burned-over forest and poor soil, heather forms a dense, evergreen mat, upright or spreading, of tiny, scalelike foliage of overlapping pairs, most often smooth and fleshy, in shades of green from light to dark and sometimes gold, chartreuse or russet. Of interest to the silver fancier are the downy silver-gray sorts, of which there are many fine examples. In winter, leaves may be tinged dull chartreuse or purple. Plants produce one-sided spikes of small, bell-shaped flowers in racemes of varying length, from 1/2 to 4 inches long. It is the presence of colorful sepals, before the plants bloom and after the flowers have faded, that gives heather its singular visual beauty, especially when massed. Heathers produce phenomenal quantities of seed that quickly establish a multitude of plants in favorable conditions. Anyone who has visited Scotland’s heaths and witnessed vast, undulating stretches of rose and purple heathers and heaths (distinguished by their darker purple flowers) can appreciate this phenomenon and its impact on the imagination and daily lives of people living within its natural range.

Heather has been used for animal fodder, fuel, plant dyes, ropes, thatching, to stuff mattresses and as medicinal preparations. Flowers are a source of nectar for butterflies and bees, and heather honey, used in the ancient drink mead, is still highly prized. Heather is also called ling, derived from the Norse lyng (lightweight, as in a lightweight fuel). These little shrubs do best wherever cool, humid summer conditions prevail, as in coastal New England and the American Northwest, but they may also be grown inland. Plant them deeply with their lower foliage touching the soil in an open, sunny site, in humus-y, acidic soil amended with sand and peat. Over-fertilizing produces leggy, unhealthy plants. Ground that supports blueberries and rhododendrons should also grow heathers.

Lavender

Lavandula spp.
Common name: lavender
Family: Lamiaceae, mint
Description: downy shrub, subshrub
Origin: Mediterranean
Site and soil: sun; sharply drained
Height and width: 12 inches to 3 feet tall; 20 inches to 4 feet wide
Hardiness: Zones 4 to10

Lavender is a classic in every sense, cultivated since ancient times to the present day. It is loved for its bracing and refreshing scent—sharp and sweet, like jasmine or heliotrope with a shot of camphor—and its foliage and flower combination. From a woody-based mound of small, usually linear, leaves, numerous straight, broom-like stems arise in summer. These are topped by slender, conical heads packed with small, two-lipped flowers—in the violet to purple range, occasionally white or light pink—in dense whorls. Flowerheads are enhanced by the beauty of bud and calyx, often flushed in shades of violet-purple. When its scent is released by the sun and suffuses the air, the entire lavender ensemble of foliage, buds, flowers and aroma is overpowering to the senses, especially when plants are massed. For the silver collector, lavender’s appeal is heightened by conspicuously downy foliage, from gray-green and silver-green to woolly white. The genus name is derived from the Latin lavare (to wash), from the Greek and Roman tradition of adding lavender scent to bath water. Medicinally, lavender has a long history of use as an antiseptic and for treating headaches, insomnia and digestion ills. Its greatest practical value has been in the commercial production of essential oil used in perfumes and toiletries, for which special varieties have been developed.

It is not difficult to grow lavender satisfactorily if certain principles are followed. In cooler climates, lavender must develop a woody base before it can survive repeated winter frosts, so for this reason it is best to begin with sizeable purchased plants. Fast-growing Lavandula angustifolia ‘Lady’ is an exception. In the humid South, lavender must be kept dry with a pebble mulch (light colored to reflect sun is best) at its base. Wherever it is grown, it must have sunny and airy conditions and soil where water never puddles. If these conditions are fulfilled, the hardiest lavender (L. angustifolia) can be grown in areas with -30-degree winter temperatures. Poorly sited lavender, no matter how hardy, will succumb. Lavenders can be left in place for many years, but with age they usually become a dense mass of woody stems with few blooms and dead patches. It is usually best to propagate them every few years. Fungal diseases, mostly a problem in hot, humid areas, include Fusarium root rot and leaf spot. Silveriness can depend on maturity of foliage (younger is greener, usually).

Sage

Salvia spp.
Common name: sage, salvia
Family: Lamiaceae, mint
Description: downy annual, short-lived perennial, subshrub
Origin: dry meadows, rocky slopes, scrubland, light woodland, moist grasslands in temperate and subtropical regions
Sun and site: sun or partial shade; dry-moist, well-drained
Height and width: 6 inches to 5 feet tall; 12 inches to 5 feet wide
Hardiness: Zones 4 to 10

Salvias belong to a large genus of about 900 species distributed around the world (more than half of them from the Americas), in varied habitats from dry and rocky to moist and grassy. Plants grow up on square stems that may become rounded in maturity, from rhizomatous or tuberous roots, and are found among very hardy to frost-tender types that must be overwintered indoors as mature plants or cuttings. In mild climates, some are evergreen.

Nectar-rich tubular or hooded flowers are attractive to hummingbirds, bees and butterflies. They bloom sparsely to prolifically on candelabras, spikes or panicles, enhanced by the colorful calyces that hold them. Flowers in the reddish purple range, as well as cream-white, create attractive combinations with generally hairy, sometimes pebbly, and textured foliage. In some Species, like Salvia argentea, leaves are quite woolly—from small and lance-shaped to huge and rounded (nearly heart-shaped), from silvery-white to gray-green.

Often flowers, foliage, or the entire plant is strongly aromatic, perhaps a defense strategy against browsing animals. Aromas may be quite pronounced, from fruity and musky to camphorous (similar to cooking sage). The genus name is based on the Latin salvage (to heal or save), and salveus (uninjured) refers to salvias’ role as an ancient healing herb as well as food. Many sages, even those regarded as “ornamental,” have a history of use in their native habitats. Native salvias, for instance, have been used for centuries by American Indians. Silver sages are workhorses of the herbaceous border for formal or informal plantings among rocks.

Russian Sage

Perovskia spp.
Common name: Russian sage
Family: Lamiaceae, mint
Description: downy perennial
Origin: rocky, open sites; Afghanistan to Tibet
Site and soil: sun; sharp- to well-drained
Height and width: 2 to 4 feet tall; 1 to 4 feet wide
Hardiness: Zones 3 to 8 or 9

From small beginnings, the merest hint of silver sprouting from bare stems in spring, Russian sage grows almost as wide as it is tall by late summer, when the entire plant is covered with small, gray, serrated leaves along its silver stalks, adorned by a multitude of tiny blue or lavender-blue flowers on slender spikes. Russian sage is neither Russian nor a sage. It is named for a Russian general and it is called “sage” because of its camphorous aroma. Russian sage has a history of use where it is indigenous. Its flowers are eaten fresh and the leaves are used like tobacco.

Immune to drought, heat, humidity, pests and diseases, growing as well in the southern United States as in the Northeast, Russian sage is a gardener’s dream come true, an outstanding plant of aesthetic value that is relatively easy to grow in virtually every region of the country.

Avoid overcrowding, any shade and rich soil, which promotes leggy, weak growth and a demand for staking. Russian sage nicely dominates the scene wherever it grows, whether as a billowy hedge, a swathe of silver within the border, or a single accent. It goes with rocks, a rock wall, or a rocky outcropping as in its native habitat. Its silvery gray foliage and lavender-blue flowers complement and improve every conceivable color from the brightest to the lightest pastels as well as white.

One of the most effective accent plantings we’ve seen was on a rise between house and driveway, where a single plant, seen from afar, resembled a wide, airy shrub. Up close, white and lilac-blue alyssum (Lobularia) planted at its feet echoed the same color above. It is a companion plant for most border stalwarts, improving all of them by its association.

The best of the Russian sages is Perovskia atriplicifolia from Pakistan, with soft blue to lavender-blue flowers. P. abrotanoides has more violet flowers and noticeably fringed leaves. P. ‘Hybrida’, a cross between these species, has longer flower spikes of lavender-blue and more fringed leaves than P. atriplicifolia. The cultivars P. ‘Blue Spire’ and ‘Longin’, which also have deeply cut foliage and lavender-blue flowers, are more upright. P. ‘Filigran’ has feathery foliage, an erect habit and long, blue flower spikes. Recently, P. atriplicifolia ‘Little Spire’, a dwarf plant, has introduced a new look. Growing 20 inches tall and 20 to 24 inches wide with the most silvery of all foliage, almost white—a great contrast to its cool, lavender-blue flower spikes—it is easier to fit into a tight border or rock garden.

More Silver Plants for Your Garden

Below are some more silvers worth checking out, organized by the feature you might be looking for:

Flowering perennials: You might like the colorful florets of yarrow (Achillea spp.) or the perfumed flowers of pinks (Dianthus spp.).
Creepers or small upright shrubs: Thyme (Thymus spp.) is beautiful in the garden, and lungwort (Pulmonaria spp.) grows under the canopy of deciduous trees.
Low, wide shrubs: Everlasting flower (Helichrysum spp.) can be up to 6 feet wide. Sun rose (Helianthemum spp.) and rue (Ruta spp.) are more moderate in their growth, at around 18 inches and 30 inches wide respectively. Lavender cotton (Santolina spp.) is evergreen, but short-lived.
Grasses: Blue oat grass (Helictotrichon sempervirens) is a middle-sized, cool-season grower. Indian grass (Sorghastrum nutans) is a tall, beautiful prairie grass.
Trees: Silver pear (Pyrus salicifolia) is a slender, deciduous tree. Willows (Salix spp.) are fast-growing.