Carpet a shady corner
Story by Hugh Skinner
Groundcover options, ranging from spring blooming perennials to native woodlanders to shade-loving creeping perennials and dwarf evergreen shrubs, can provide easy-care cover with the interest and excitement of spring flowers and colourful foliage, or understated background to emphasize flowers of impatiens or begonias. Here are some options for ground cover in shade.
Add excitement to your spring landscape by planting spring ephemerals. These early-spring-blooming plants adapted to growing in the forest understorey by blooming before the leaves emerge on the trees.
The genus Hepatica is closely related to anemones. The blue, pink or purple flowers of H. nobilis and H. transylvanica appear above evergreen foliage almost as soon as the snow disappears. Over the years the plants spread to several feet across and provide a spectacular early spring show.
Cowslip primrose (Primula veris), with its yellow or red flowers, carpets shady corners with crinkled bright-green foliage. Dusty miller primroses (P. auricula and hybrids) have farinose (floured) light-green leaves and flowers in shades of red, blue and yellow. They thrive in well-drained shady locations but will tolerate more sun.
Lungworts (Pulmonaria species) are attractive companions to spring flowering bulbs. The spotted leaves of most species have given rise to both the Latin name (Pulmonaria) and the common name. Common lungwort (Pulmonaria officinalis) has heart-shaped dark green leaves spotted with silver. Its flowers open red and fade to blue. Roy Davidson Bethlehem sage (P. saccharata ‘Roy Davidson’) has handsome strap-shaped foliage with extensive silver spotting and light blue flowers.
Alpine forget-me-not (Brunnera macrophylla) greets spring with airy clouds of tiny azure-blue flowers. It prefers a rich moist soil. Native to the Caucasus mountains, the species has dark-green bristly oval leaves but cultivars ‘Hadspen Cream’ and ‘Variegata’ have variegated foliage with bands of white or cream on the edges of the leaves while ‘Langtrees’ have unique silvery speckled leaves. Creeping forget-me-not (Omphaloides verna) develops a mound of medium-green-hairy foliage with small tubular white flowers in spring. It will thrive in dry shade, often a difficult planting site.
Creeping shade-tolerant perennials cover the ground as they root and produce mats of attractive foliage, flowering during the late spring or summer. Use them as ground cover to unify plantings or to divide areas of lawn.
Siberian barren strawberry (Waldsteinia ternate) will also grow well in dry shady areas but will thrive as long as the soil is not saturated. The handsome evergreen foliage, resembling strawberry leaves, is topped by yellow disc-shaped flowers in spring. It spreads by runners to form a dense mat that effectively keeps weeds from getting a hold.
Spotted deadnettle (Lamium maculatum) and yellow archangel (Lamiastrum galeobdolan) are closely related members of the mint family that creep along the ground and take root where stems touch it. Both have attractive silver-spotted foliage. There’s an obvious difference, though: the flowers of Lamium maculatum are pink or white while those of Lamiastrum galeobdolan are yellow. Both species and their cultivars are effective ground covers in moist shady corners.
Some hardy geraniums (Geranium spp.) are tough easy-to-grow plants that adapt well to the shady understorey. Bigroot geranium (G. maccrorhizum) and its varieties suchas ‘Czakor’ are tough plants with aromatic leaves and showy early summer flowers. Hybrids with alpine geranium (G. dalmaticum) are more compact plants with shiny foliage. ‘Cambridge’ has rose-pink flowers while ‘Biokova’ has white flowers with red stamens.
Periwinkle (Vinca minor) has thin green stems that root periodically where they touch the ground to form dense cover of shiny oval evergreen leaves. Round blue, white or purple flowers appear in late spring.
There are variegated cultivars with gold or silver edged leaves. In the prairie climate periwinkle thrives in locations where plants are protected from afternoon sun to prevent the foliage from burning in spring. Although not as readily available, herbaceous periwinkle (Vinca herbacea) is a similar plant that loses its leaves over winter but is more adaptable and will grow in shade or in sun.
Hosta species and cultivars are excellent groundcover plants for light to deep shade. They thrive in rich well-drained soils and once established will grow for many years with little care or attention.
The foliage can vary from dark green to intense blue to golden yellow, with many well-known variegated cultivars. They range in size from the 15 centimetres (six inches) high ‘Lemon Lime’, ‘Lime Tiara’, ‘Golden Tiara’ and ‘Gingko Craig’ to the 40 cm tall ‘Pearl Lake’, ‘Blue Boy’ and ‘Gold Drop”, to the 60 cm ‘Francee’ and ‘Gold Standard’ up to 90 cm ‘Sum and Substance’. Use low growing cultivars as edging or ground cover in small beds while taller-growing varieties can naturalize to provide background or delineate spaces in the garden.
Walk along a woodland path and note colonies of twinflower (Linnaea borealis), bunchberry (Cornus canadensis), Canadian ginger(Asarum canadense), or Western Canadaviolet (Viola canadensis). These are among native low-growing perennials that can be established in a shady area in the garden. Where taller plants are appropriate, consider planting ostrich fern (Matteuccia struthiopteris), false Solomon’s seal (Smilacina stellata) or sarsaparilla (Aralia nudicaulis).
Dwarf broad-leaved evergreen shrubs
Bearberry (Arctostaphlyos uva-ursi) is a native creeping shrub with small oval evergreen leaves. Its pale pink urn-shaped flowers produce red berries in the fall. It will grow in sun or shade in well-drained soils. Canby paxistima or cliff green (Paxistima canbyi)is an attractive dwarf shrub with tiny oval evergreen leaves. Its unique orange rhizomes give rise to stems that spread to form a dense ground cover. Plant it in a narrow bed along the foundation of a house or under trees. Japanese spurge (Pachysandra terminalis) has dark-green glossy foliage and rather inconspicuous white flowers at the ends of the stems. Given time, it forms dense cover. The variegated forms have not endured in this writer’s garden.
These are a few of the many plants you can use to unify plantings, to shade the soil and to limit weed growth in shady garden beds. Attractive foliage will add interest to plantings. Spring or summer flowers attract attention for their colour.
Hugh Skinner, co-author of Best Trees and Shrubs for the Prairies, operates the Frank Skinner Arboretum near Roblin, and for 30 years has been involved in testing and in the nursery production of a wide variety of hardy plants.