When it comes to landscape design, not much attention is paid to ground covers. Typically, landscapers focus on shrubs, trees and perennials – the key elements of landscape design. More often than not, ground covers are treated as a practical solution for erosion control, weed suppression, or moisture retention. They are not given the credit they deserve for creating texture in the landscape or for the role they play in visually tying together the compositional elements of a garden.
The upside to many ground covers is that they tend to spread widely and fill in problem areas very quickly. The downside to ground covers is that they don’t always play nicely with others and – let’s face it – in many cases, they can be downright invasive. Because of their natural inclination to spread, they may grow well beyond their intended boundaries and crowd out other plants. Worse yet, they may escape into other areas of the garden or into the lawn and become a nuisance. Pachysandra (Pachysandra terminalis) is just one example of a popular ground cover that can be a problem. It generally behaves itself when planted in dry, rocky soil where it has to compete with tree roots for moisture and nutrients. However, when planted in loose, fertile, moist soil, it can spread aggressively and may require some serious intervention to keep it contained. A better strategy is to choose a ground cover that spreads slowly and can be more easily controlled. An Epimedium is an example of just such a plant.
WHAT IS EPIMEDIUM?
The Epimedium genus is an herbaceous member of the barberry family (Berberidaceae) of plants. The good news is that it shares none of the invasive characteristics for which some woody members of that family are known. It has many common names of which the best known are barrenwort (because it was believed to cause barrenness in women), bishop’s hat (because the flowers resemble a clergyman’s mitered hat) and fairy wings (because the dainty flowers hover above the foliage like butterflies or fairies about to take flight). Low-growing Epimediums average 8 to 12 in. in height. Depending on the selection, they form either a low mound or a gently spreading ground cover. They grow best in a shady or semi-shady area in gardening zones 5 – 8.
Epimedium leaves are generally heart-shaped, graceful, and most charming, particularly in the spring. There’s a great deal of variety both in leaf size and color. Some selections, such as the one shown in the accompanying photo* of E. stellulatum ‘Long Leaf Form’, have elongated leaves that are shaped much like arrowheads. The emerging spring foliage of many selections varies widely in color, with many selections exhibiting reddish coloration or markings.
The accompanying photo of E. x youngianum ‘Royal Flush’ shows an example of that cultivar’s gorgeous spring foliage. As the foliage matures, it changes to solid green in summer or to green with reddish markings. A particularly beautiful example is shown in the photograph of E. sempervirens ‘Cherry Hearts’.
In early spring, the flowers appear in clusters on long arching scapes. Depending on the species and cultivar, flower colors include white, red, pink, purple, yellow, orange and various bi-color combinations.
A great deal of hybridization has taken place to expand the floral color palette. In my opinion, the delicate flowers are certainly charming but it’s the amazing foliage that endears me to this plant.
The photo of E. x versicolor ‘Sulphureum’ is an example of a yellow-blooming selection. Its newly emerging spring foliage has rusty-red markings and is quite striking.
Epimediums are naturally distributed in areas around the Mediterranean Sea and Eastern Asia. Those species that evolved in the Mediterranean area tend to be evergreen and drought tolerant once they are established. Species that have been introduced from Asia are not as drought tolerant as their Mediterranean cousins and prefer rich, moist soil. They also tend to die back in fall and re-emerge in spring with fantastic variations in foliage, texture, and color. Some varieties turn red, yellow or bronze for a second flush of color as temperatures drop in the fall.
In his second edition of Herbaceous Perennial Plants (1989), author Allan Armitage described Epimedium as “a genus whose time has come, with plenty of attributes and very few faults.” Since that edition was published, there has been an explosion of interest in the genus due to the discovery of many new Asian species, largely from China, and to extensive breeding work of commercial plant developers, such as Darrell Probst of Massachusetts, as well as a number of non-commercial growers and enthusiasts. As a result, literally hundreds of cultivars now exist with more in the works.
Epimediums are generally trouble free. Deer and voles normally don’t bother them but rabbits have been known to nibble the tender spring foliage. Slugs and snails may occasionally chew the foliage but they don’t usually do any lasting harm to established plantings.
HOW TO USE EPIMEDIUM IN THE LANDSCAPE
Epimediums can be used in a number of interesting ways in the landscape. For example:
- In a mixed shade garden, plant it as a ground cover where it can gradually fill in the spaces between trees and shrubs and serve as a living mulch.
- Plant it as a border along a woodland path. The foliage will soften the edges of pathways and lend movement to the landscape as the wind ruffles the individual leaves.
- If you have lots of taller plants in a shade garden, use lower-growing Epimediums as an edging or border. The small heart- or arrowhead-shaped foliage makes a nice transition between lawn and garden plantings.
- Use it in a shaded rock garden setting where its low-growing habit will harmonize with similar ground-hugging plant forms.
- Plant it as an accompaniment to spring bulbs. The colorful emerging foliage will add additional interest and texture to a spring bulb display. Another advantage is that it will help hide dying bulb foliage.
- Use it to help solve an erosion problem. The dense, rhizomatous root system is ideal for holding soil in place. Bear in mind, however, that this plant may not be the most practical choice for a large area due to its slow growth rate. Also, it is a more expensive solution than the cheaper (but aggressive) ground covers such as bugleweed, ivy, vinca, or pachysandra).
- Create a complex woodland tapestry by interspersing Epimediums with other shade-loving ground covers. With so many shade plants to choose from, the biggest challenge is to select just two or three other species so that the design doesn’t become too busy. A few complementary species that come to mind include: Allegheny spurge (Pachysandra procumbens), columbine (Aquilegia canadensis), ferns, fringed bleeding heart (Dicentra eximia), hostas, Lenten rose (Helleborus), lungwort (Pulmonaria), pigsqueak (Bergenia cordifolia) and wild ginger (Asarum canadense).
HOW TO GROW EPIMEDIUM
Epimedium is a great solution for dry shade conditions where other plants may struggle. It competes well with tree roots, is not bothered by rocky soil, thrives in dry soil, and tolerates lower light levels. These are, however, the worst-case growing conditions. While a clump of Epimedium can easily tolerate these less-than-ideal growing conditions, it will perform best if you:
- Select a garden spot with light shade or dappled light. This plant can take some morning sun but cannot tolerate hot mid-day or afternoon sun. If you don’t have an ideal garden spot, try planting it on the north side of the house or near taller plants or other structures that will cast a shadow in the afternoons. It will also grow in pots, which might be easier to manage.
- Verify (by doing a soil test) the pH of the soil before you plant. Most Epimedium species prefer neutral to slightly acidic soil. However, many of the newer varieties from China grow well in alkaline soil. Hybrids and selections of the Japanese species prefer acidic soil with a pH between 5 and 7.
- Plant in moist but well-drained neutral to slightly acidic soil. Epimediums do not like heavy soil that is soggy or holds water.
- Loosen the soil in a dry or rocky site as best you can and work some compost or well-rotted leaf mold into the planting hole.
- Space the plants about a foot apart. Actual spacing depends on the specific growth habit of the species or cultivar you select. The clumps will gradually grow together, filling in the empty spaces as they spread.
- Water new plantings regularly until they are well established.
- Shear the foliage of the evergreen varieties back to the ground before the flower spikes emerge in spring because, despite being evergreen, the foliage tends to look a bit tattered by then. Unlike deciduous species, which turn brown and fall off on their own in autumn, evergreen species do not fall off even when they become tattered or skeletonized.
HOW TO PROPAGATE EPIMEDIUM
Epimediums are best propagated by division. This plant is slow to colonize but it can eventually exceed its allotted space in the landscape. Divide it in spring after flowering has finished or later in summer or early fall, preferably on a cool, cloudy day. TIP: Moisten the soil before you try dividing the plant. That will ease the task of slicing through the mass of dense, fibrous roots. Also, use a sharp spade or a serrated knife for this task.
Whether you are a novice gardener or a serious plant collector, you can’t go wrong with Epimedium. It is long-lived, tough as nails, low maintenance, deer resistant, and drought tolerant. Its delicate flowers and beautiful foliage make it interesting all season long. With so many species and cultivars to choose from, don’t limit yourself to just one. Although it is slow to spread, be patient and this plant will reward you with a fascinating combination of color, form, and texture in your shade garden. Best of all, it plays nicely with others.
A-Z Encyclopedia of Garden Plants (American Horticultural Society, 2008).
“An Evaluation Report on Barrenworts for the Shade Garden,” by Mark R. Rudy, Plant Evaluator, Chicago Botanic Garden, Plant Evaluation Notes, Issue 20 (2003).
Armitage’s Garden Perennials, 2d ed. (Armitage, Allan M., 2011).
“Epimediums: Queens of the Woodland,” Pacific Horticulture Magazine, Vol. 69, No. 2 (Apr. 2008).
Herbaceous Perennial Plants, A Treatise on their Identification, Culture, and Garden Attributes, 3d ed.(Armitage, Allan M., 2008).
The Plant Lover’s Guide to Epimediums (Gregson, Sally, 2015).
*Photo of Epimedium stellulatum ‘Long Leaf Form’ used with the permission of Carolyn Walker, http://carolynsshadegardens.com/.