Geranium macrorrhizum in bloom.
Ground covers are an important component of any landscape and are really more common than you might think. Your lawn is comprised of ground cover plants, typically Kentucky bluegrass, some other type of cool or warm-season grass, white clover or other low-growing types of plants. Getting grass to grow in the shade is a common complaint of gardeners. In many cases some other kind of ground cover might be the solution.
Ground Cover Plant Benefits
Ground cover plants generally serve the following purposes:
- Cover the soil to protect it from erosion by wind or water.
- Shade the soil to reduce the likelihood of undesirable plants to become established.
- Shade the soil to keep it cooler and reduce water loss from it.
- Occupy the soil itself with roots to compete with potentially invasive plants.
- Add beauty and interest to a landscape.
Most ground cover plants will spread out over or in the soil, producing new plants as they grow. Rhizomes are underground stems utilized by some plants like lily of the valley while stolons, spreading above ground stems, are produced by other plants like bugle weed. Grasses and other monocotyledonous plants may produce offsets or tillers to expand the territory that they cover. These are all great characteristics for a ground cover to have, particularly in challenging locations like a hillside that is prone to erosion and needs to be stabilized. But, that same propensity to spread can also make many of these plants aggressive competitors with other desirable plants that might also be in the landscape. So, choose your ground cover plants carefully so that you do not end up with a mass planting that is on its way to take over your garden a few years after it was planted.
Aegopodium podagraria ‘Variegatum’
Aegopodium podagraria ‘Variegatum’ (Bishop’s Goutweed) is a ground cover that I need to mention. This is one of the toughest ground covers you are going to find. The foliage grows up to about 10” tall and is usually green variegated with creamy white. In early summer it umbels of white flowers that may grow an additional 4 to 6” above the foliage. In moist shade and in good soil this plant can rapidly cover fairly large areas of the ground, making it a good alternative to poorly growing grass in some cases. But you had better be careful to keep it in bounds or you may be sorry you got it planted. In most cases however it grows much more slowly and works well for more out-of-the-way areas. If it gets too dry, the leaves may turn a bit brown. Just run the mower over them in mid-summer to see a fresh crop of new foliage spring up in the fall. It performs best in part sun but can grow well in sunnier locations if it has adequate moisture.
Ajuga reptans (Bugle Weed) is one of the easiest and most reliable ground cover plants to grow. It readily spreads by stolons that grow along the surface of the ground producing new plantlets that root down and expand their colony of plants. The common name of bugle weed comes from the appearance of the blue tubular flowers that are borne around the nodes on the 6 to 8” stems in June. There are several cultivars that have foliage in plain green, burgundy green or variegated with white and pink.
Asarum canadense & Asarum europium
Asarum canadense (Wild Ginger) and Asarum europium (European Wild Ginger) are two very interesting ground cover plants with rounded, heart-shaped leaves and prostrate stems that creep along the ground. One of the easiest ways to tell these two species apart is that A. canadense has slightly hairy leaves and stems while A. europium has glossy leaves and stems. The flowers are tubular, about 3/4” in diameter with three pointed petals. They practically lie on the ground to facilitate pollination by ground dwelling insects. While the stems do have a distinctive gingery aroma, these are not considered to be edible plants.
Asarum canadense (wild ginger).
Asarum europeam plants.
Chinese Astilbe, False Spirea
Astilbe chinensis (Chinese astilbe, false spirea) is another plant best adapted to a partly sunny location with humus-rich soils and a fairly consistent supply of moisture. In early summer striking, fuzzy-looking flower spikes are produced in colors of white, pink to red. The ternately compound leaves are attractive all season long, even after the flowers have faded.
Brunnera macrophylla (Siberian Bugloss) is another great shade garden plant. It grows to about 10” tall and a foot wide with broad, rounded leaves. The leaves are somewhat heart-shaped, may be plain green but more likely with speckles or mostly covered with silvery markings with only the small veins remaining green. Brunnera produces small blue flowers in late spring that are quite delicate and pretty. Its rounded leaves can make a nice contrast to those of hosta which are usually much more elongated and narrow.
Lily of the Valley
Convallaria majalis (Lily of the Valley) has one of the most sweetly scented flowers of our perennial flowering plants. Each plant usually has only two or in some cases three fairly wide, strap-like leaves. A flower stalk grows up through the coiled leaves early in the spring to finally bloom usually in mid-May. Flowers are usually bright white but C. m. ‘Rosea’ has pink flowers. Convallaria is an aggressive spreader once established, increasing its territory through short rhizomes called pips that grow beneath the soil. This can be a very aggressive spreader. Plant it where it can spread or else install some sort of barrier that extends at least 6” below the ground. Lily of the valley will tolerate full sun if it has adequate moisture, otherwise it may show signs of scorch during hot and dry summer weather. Therefore, a partly shaded location is preferred but it will even tolerate shade.
Barrenwort, Bishop’s Hat
Epimedium hybrid (Barrenwort, Bishop’s Hat) is a little-used perennial that is best adapted to a woodsy, location, partial sun to shade and with a fairly consistent supply of moisture, but it will grow in dryer locations, just more slowly. In the early spring, often before leaves are fully developed, clusters of four-petaled flowers in white, lavender, pink or yellow emerge, slightly suspended above the foliage. The leaves are two or three times ternate and usually emerge with a maroon coloration along the edges. These Asian native plants are certainly an interesting plant worthy of trying in the landscape.
Galium odoratum (Sweet Woodruff) is another ground cover plant for the partly shaded garden. It has fine, palmately compound leaves and clusters of small star-shaped flowers in the spring. It spreads nicely in the garden, particularly with adequate moisture. Once flowering is complete, its foliage looks good the rest of the summer. The leaves emit a sweet fragrance when crushed.
Big Root Geranium
Geranium macrorrhizum (Big Root Geranium) is just one example of the different hardy geraniums that can be grown in our gardens. While many gardeners are very familiar with the common annual geraniums, actually Pelargonium that are sold as bedding plants, hardy geraniums work well in many locations and can provide a nice floral display, attractive foliage as well as fall color in some cases. One of the best spreaders, and therefore a good ground cover is the big root geranium. It has leaves similar to a Pelargonium with their general rounded shape and slightly scalloped edge, but stays relatively short, only about 8 to 15” tall. In early summer many flower spikes develop, usually in shades of white, pink or lavender. Each flower spike will usually only have about six to eight florets, fewer than the typical Pelargonium.
Coral Bells, Foamy Bells & Foam Flower
Heuchera sanguinea, Heucharella, Tiarella
Heuchera sanguinea (Coral Bells), Heucharella (Foamy Bells) and Tiarella (Foam Flower) are a group of closely related genera that all fit into about the same niche in the landscape – part shade with a fairly consistent supply of moisture. They are so closely related that they have been frequently used to create intergeneric and interspecific hybrids. While most of these plants are noted for their showy foliage, some have quite attractive flower spikes that range in color from white to pink and red. Generally, they are clump-forming plants that will generally increase in size so will look their best when planted in groups of at least five plants.
Heuchera sanguinea 'Snow Angel' blooming.
Heucherella 'Solar Power'.
Lamiastrum, Yellow Archangel
Lamium (Lamiastrum) galeobdolon (yellow archangel) is a good ground cover for shady locations. The species can be rather aggressive with its quickly growing stems and opposite medium green leaves with silvery markings along the margin. So, one must be careful where one chooses to plant it so its aggressive nature does not become a problem. A non-spreading cultivar ‘Herman’s Pride” only grows about 8 to 12” tall and wide and has similar yellow, tubular flowers to the species.
Lamium maculatum (Spotted Deadnettle) is an excellent ground cover plant that has attractive foliage and pretty flowers that appear in profusion in mid-spring then sporadically over the course of the summer and fall. The leaves are fairly small, about 1” in diameter. They may be plain green but are usually spotted or banded in silver-gray. Some varieties have leaves edged in gold-yellow. The flowers are borne in small spike about 6” tall and may be white, pink or lavender. Lamium spreads by creeping stems over the soil where they will root down and form new plants. It can make a fairly dense ground cover that will hold soil in place and compete fairly well with weeds.
Lysimachia nummularia (Moneywort) is another aggressive ground cover plant that only grows about 2 to 4” tall when in bloom. It has small, round, 3/4” opposite leaves that form along its thin, prostrate stems. This plant will form a dense mat of foliage that will block out most weeds. It looks great creeping over the edge of a wall or rocks and puts on quite a show when the small, bright yellow flowers appear in summer in profusion. The most commonly sold cultivar, ‘Aurea’ also has golden-yellow foliage. This plant will grow well in full to part sun.
Lungwort or Spotted Dog
Pulmonaria (Lungwort or Spotted Dog) is a shade garden “must-have”. It is one of the best plants for shade, next to hostas. It has great looking foliage from spring to hard freeze and lovely white, pink or lavender flowers in the spring. Pulmonaria or lungwort got its name from some early plant geek that thought the leaves looked like diseased lungs. Perhaps it is better to remember the botanical name or the other, much more likable common name of spotted dog. The leaves of these plants usually have silvery, mottled spots. In some cases, the entire leaf is so covered with spots it just looks silvery-green. Pulmonaria is about a foot tall when in bloom with only small, narrow leaves present along the stem. Then those stems die down while fresh, larger leaves grow up to take their place. Lungworts spread slowly in the garden, eventually forming nice clumps of plants about 12 to 18” wide.
Pulmonaria 'Dark Vader'.
Pulmonaria in full bloom.
Vinca minor (Common Periwinkle) is a low-growing, twining, perennial plant with glossy, evergreen foliage. The smooth stems will often root down as they creep along the ground, making it an effective ground cover, particularly for stabilizing slopes. It produces tubular, lavender flowers in late spring and again intermittently over the course of the rest of the summer. It grows in average soils and performs best in full sun to part shade but it can also tolerate full shade.