Horticultural luminaries John L. Creech and Donald Wyman have called woody shrubs “one of the most important groups of commonly grown plants,” but herbal woody shrubs are often overlooked. Deemed herbal because of their fragrance or uses, many hardy herbal shrubs are available to today’s herb gardener.
When herbal shrubs are included in the landscape, they add beauty, fragrance, and functionality. Shrubs that have herbal uses and aromatic qualities can extend a garden’s herbal theme. Woody plants useful for medicine, seasoning, fragrance, or crafting add a feeling of permanence.
Using Herbal Shrubs
Shrubs have many functions, including hedges for screening, grouped plants for transitions between trees and perennial herbs, and single plants as focal points.
Hedges and screening enclose spaces in the garden. If you are not lucky enough to have serpentine brick walls (my ultimate goal), try surrounding your garden with a clipped evergreen hedge. For example, I chose a native dwarf holly, Ilex vomitoria ‘Schelling’s Dwarf’, to surround my Shakespeare Garden. It encloses an oval 40 feet long by 30 feet wide. Although it needs the gas-powered hedge shears once every year or two to keep it from spreading outward, it never grows too high. Taller hedges can create useful visual barriers, physical barriers, and windbreaks and contribute to the design or pictorial effect of the landscape.
Hedges can add drama and excitement to the garden. Many gardeners can remember hedge features from gardens they’ve visited, such the famous central roundel at Sissinghurst Castle, the garden of Vita Sackville-West. Colonial Williamsburg in Virginia boasts eight miles of tightly clipped evergreen hedges.
Deciduous herbal shrubs may also be used for hedges. I’ve seen the old flowering currant (Ribes sanguineum) clipped into a very dense, pretty hedge. It had bare branches in winter but was clothed in a mass of pink flowers in April. This year, clipped American beech, Fagus americana, showed up as a hedge in two of the Atlanta gardens on the “Gardens for Connoisseurs Tour.”
Plants useful as transitions between herbaceous perennials and trees range in size from the diminutive woody herbs such as thymes, sages, and rosemaries (known as sub-shrubs) to stately, multi-trunk shrubs like serviceberry (Amelanchier stolonifera) and bay laurel.
Seasonal flowers, fragrance, textural foliage, colorful bark, berries, and leaves are among the features that might recommend an herbal shrub for use in a mixed border. Spreading shrubs are useful as large-scale ground covers and to fill in horizontal spaces. Larger shrubs can act as scaffolding for climbing roses, golden hops, or fragrant honeysuckle vines to grow up through their branches or as background to a mixed border, creating a stair-stepped planting scheme.
Graceful, arching shrubs that are naturally vase-shaped may be underplanted with more traditional herbaceous favorites or with bulbs to mask bare, leggy lower branches. And finally, dwarf shrubs, those classified as knee-high or waist-high, are useful for ground covers, low edging, or definition in the garden, and largely eliminate the need for pruning.
A third traditional use for shrubs in the landscape is as a single specimen chosen to be a focal point in the garden–an individual plant grown for its own sake. Herbal shrubs with several seasons of interest, such as doublefile viburnum, quince, and blueberry are good selections. Sometimes the shape or height of the specimen shrub is important. Tall columnar shrubs such juniper or fastigiate yew, the traditional herb of mourning, provide a vertical element that serves as an exclamation point in the herb garden.
Broad-Leaved Evergreen Shrubs
These shrubs are an indispensable part of the garden, and they play many roles.
Laurus nobilis, the revered bay laurel of antiquity, must be grown in a large tub and brought inside, as it will winter-kill at temperatures lower than about 15° F. It stays outside in my garden in Atlanta except for a day or two each winter, when I roll it into the garage. A popular seasoning herb, it thrives in part shade.
The elusive daphne has a reputation for being finicky. Sackville-West recommends a spongy soil, rich with humus and sand, with overhead shade in the summer. My friend Julie, who just moved within Atlanta had grown her winter daphne (Daphne odora) in a large pot on her terrace for seven years. Now that she has a larger garden, she hesitates to transplant it, repeating the expression, “if it ain’t broke, don’t fix it.” Her pot-dwelling daphne perfumes the air during its winter bloom season.
The leathery, aromatic evergreen leaves of shrubs in the anise family are sure to delight, but not so the maroon red flowers of Florida anisebush (Illicium floridanum). Nicknamed “chicken livers,” they are so malodorous that I am glad I planted them beyond the garage. But I’m not growing this plant for scent; I love it for its beautiful star anise seed pods, with cinnamon-colored seeds as shiny as patent leather. I also appreciate the tall screening–just under 10 feet–that it provides.
Smaller broad-leaved evergreen sub-shrubs include the favorites rosemary and lavender. In my climate, rosemary blooms in wintertime with blue flowers on old wood. And Lavandula angustifolia ‘Hidcote’ and L. angustifolia ‘Munstead’ often bloom twice a year, in April and again in October. I prune the long flower spikes immediately after flowering as next year’s flowers form on the tips of the branches. The ever-gray foliage is fragrant even when the plant is not in bloom.
Silvery-gray lavender cotton (Santolina chamaecyparissus) and its close relative green santolina (S. virens) act as woody perennials in the herb garden and are covered with bright yellow button flowers each summer. Finally, narrow-leaf French thyme (Thymus vulgaris ‘Narrow-Leaf French’), which grows only 12 inches tall, is my favorite to use in tussie-mussies, symbolizing courage.
Using Evergreens as Screens
The traditional use of holly, aside from yuletide decorations, is for screening. Small-leaved hollies including inkberry, winterberry, yaupon, and Japanese holly do very well when clipped and are ideal as low hedges. Larger holly cultivars with large leaves, such as Ilex ‘Nellie R. Stevens’ or ‘Emily Brunner’, must be hand-pruned and not sheared, lest the leaves look ragged.
While the common privet, used medicinally as an astringent, is not very attractive, its shiny-leaved evergreen relatives, California privets (Ligustrum ovalifolium) and Texas privets (L. japonicum ‘Texanum’) may be selected for a bold, vase-shaped shrub with aromatic, creamy white panicles of flowers followed by shiny black berries.
Possibly my favorite herbal shrub for screening is bayberry (Myrica pensylvanica) or its southern sister M. cerifera, known as Southern wax myrtle, which obligingly grows in sun or shade, wet or dry soils, and on fertile or infertile sites. The leathery leaves, twigs, and all parts of the shrub are highly aromatic, and waxy gray bayberries blanketing the branches of female plants can be stripped off and added to melted candle wax to yield a wonderful bayberry fragrance.
These species are an important group of herbal shrubs. Junipers, for example, rank as the toughest of evergreen landscape plants, come in a wide variety of sizes, shapes, and colors, and are widely used in every climate zone. Common juniper (Juniperus communis) was used medicinally as a diuretic and stimulant. The fleshy cones, or berries, give the characteristic aromatic flavor to gin. Numerous dwarf cultivars are available and useful in the herb garden. ‘Hibernica’ and ‘Fastigiata’, the blue-green Irish junipers, have a rigid columnar shape. The Eastern red cedar (J. virginiana) is used as a dye plant.
Pines are important herbal trees, providing timber, wood pulp, turpentine, tar, rosin, pine oil, and edible pine nuts–but few of them fall into the category of shrubs. Pinus mugo varieties are usually prostrate ground cover pines, although there is great variation in habit.
A third evergreen, the English yew (Taxus baccata) is symbolic of mourning and is traditionally planted in cemeteries. Yew is outstanding for formal clipped hedges and topiary. Southern yew (Cephalotaxus harringtonia) has the same black-green foliage.
Deciduous Herbal Shrubs
The queen of all deciduous flowering shrubs is the rose, and fragrant heirloom roses are especially suitable for the herb garden. In the words of Sackville-West, “The old roses are a wide subject to embark on. You have to consider the Gallicas, the Damasks, the Centifolias or Cabbage, the Musks, the China, the Rose of Provins. . . all more romantic the one than the other, whose very names suggest a honeyed southern dusk. Although most of them suffer from the drawback of flowering only once during a season, what incomparable lavishness they give, while they are about it. They have a generosity which is as desirable in plants as in people.”
Steeped in history, the apothecary rose (Rosa gallica ‘Officinalis’), the Damask rose (Rosa ¥damascena), source of attar of roses, and the parti-colored York-and-Lancaster rose, R. ¥damascena ‘Versicolor’, –a symbol of the union of two mighty families–are just the tip of the rose world. Just to begin to discuss roses as shrubs is to risk becoming completely sidetracked. It’s enough to say most herb gardeners want one, then another, then a dozen….
Related to the rose is the quince (Cydonia oblonga), with its great yellow pear-shaped fruits used for mint and thyme jellies, and the flowering quince (Chaenomeles speciosa). My favorite quince for late winter beauty is C. speciosa ‘Apple Blossom’, whose pink and white blossoms are a knockout early in the gardening year. The white-flowering ‘Nivalis’, given to me by my friend Billie, flowered for the first time last January, right outside my husband’s studio window. It was gorgeous underplanted with white hellebores and white-veined Italian arum.
Fairies are said to hold hands and dance rings around the elderberry (Sambucus canadensis), a member of the honeysuckle family. We had small starts of a lovely white variegated elderberry at Herb Education Day at the Atlanta Botanical Garden last April. Elderberries are easy to grow in any soil. Their attractive masses of white flowers are dried and used for tea, and their fruit is used in pies, jellies, and wines. The flat-topped blooms of English elder (S. nigra) appear in spring; this elderberry is also used as a dye plant.
The large Viburnum genus contains many garden-worthy species, including Korean spice (V. carlesii) for fragrance and the easy-to-grow and sweet-scented hybrid V. ¥burkwoodii. European cranberry bush (V. opulus) is used medicinally, while the fruit of the American cranberry bush (V. trilobum) makes good jellies. Berries in this genus are handsomely colored, persistent, and a favorite food for birds.
My Favorite Miscellaneous Shrubs
The mid-sized, blue-flowered bluebeard or blue spirea (Caryopteris ¥clandonensis ‘Dark Knight’) is another deciduous shrub suitable for the herb garden. Its leaves, stems, and flowers are pleasantly scented and grow hard and shrubby in Atlanta. My friend Heather grows hers in an herbaceous border in Princeton, cutting it to the ground each spring.
Butterfly bush (Buddleja davidii) sports long wands of fragrant flowers that draw honeybees and butterflies. I like the deep purple cultivar ‘Lochinich’. Another species in the same genus, B. lindleyana, was given to me by my octogenerian friend, Florence. It’s a smaller shrub that tolerates part shade. But it suckers from the stems so prolifically that I’ve had to relegate it to a more out-of-the-way area.
Brooms (Genista tinctoria and Cytisus scoparius) produce a solid mass of brilliant flowers covering the green stems of the shrub. According to English legend, William (soon to be known as the Conqueror) stuck a sprig of broom–signifying humility–in his hat just before he crossed the English Channel in 1066. It worked; with his victory, he became the first of the long line of Plantagenet (from planta genista) kings.
Finally, witch hazel (Hamamelis virginiana) holds a special place in my memory. Ideal as a picked flower, witch hazel is very long-lasting and comes in colors from dark cinnabar through the palest yellows. The Chinese and Japanese species, H. mollis and H. japonica, are winter bloomers. I will long remember the day in 1975 when I met as a student with my role model, Elizabeth Scholtz, then director of the Brooklyn Botanical Garden and the only female to hold such a position at that time. Blooming on her desk in the dead of a New York winter, scenting the entire room, was a beautiful spray of witch hazel. To me, the fragrance of witch hazel will always evoke the heady heights of the horticultural world.
Incorporating herbal shrubs pays big dividends. They add dimension, fragrance, color, variation, and a welcome break from higher-maintenance plants.
Geri Laufer, the public relations manager at the Atlanta Botanical Garden, has assembled a collection of fifty-six kinds of viburnum and more than two dozen magnolias, along with all the herbal shrubs discussed in the article, in her garden outside Atlanta, Georgia.