Soil erosion is a major problem in areas of the landscape having steep topography. In addition to making the landscape attractive, groundcovers are excellent at minimizing soil erosion. While grasses provide the quickest and most effective groundcovers, there are many areas where grasses do not grow well. This often is the case in areas that are too shady or wet. In other areas, mowing may be difficult to impossible, making other groundcovers a logical choice.
By definition groundcovers are (relatively) low, dense-growing plants requiring minimal maintenance that establish a monoculture in areas of the landscape. Â In short, they cover the ground in an attractive manner. They can be classified according to several criteria. Among them are shade tolerance, persistence of foliage, height and rate of growth.
One of the most popular groundcovers is vinca or periwinkle (Vinca minor). It has a growth habit that trails along the ground, roots easily and grows to a height of about six inches. Although it produces attractive, light-blue flowers early in the spring, its dark, evergreen leaves are the plant's main attraction. It is fairly shade-tolerant which makes it a suitable choice for the north sides of buildings or under the light shade of trees. It tolerates full sun, if given adequate moisture. Vinca does not tolerate wet soils.
Another common groundcover is purple wintercreeper euonymus (Euonymus fortunei var. coloratus). The species is a woody vine that creeps over the ground until it finds a tree or fence to climb. It produces orange-red berries and is sometimes referred to as evergreen bittersweet. The species is on Missouri's invasive plant list. The botanical variety coloratus rarely blooms. Thus it seldomly produces berries and is much less likely to be spread to the wild. Euonymus scale is an insect pest that commonly plagues but rarely kills this plant.
On dry, sunny locations the creeping junipers (Juniperus spp.) make excellent groundcovers. Most achieve a mature height of only six to ten inches and spread widely. Although there are many cultivars available; blue rug juniper (J. horizontalis 'Wiltonii') is one of the best and most popular. Andorra juniper (J. horizontalis 'Youngstown'), sargent juniper (J. chinensis 'Sargentii') and Japanese garden juniper (J. procumbens 'Nana') are slightly taller cultivars.
Ajuga or bugleweed (Ajuga reptans) is another popular groundcover for shady areas where adequate moisture or irrigation is available. It can be damaged severely to the point of partial die-out during severe winters without snow cover. Several cultivars are available with bronze, nearly black or variegated leaves. All bear blue flowers in the spring. The leaves form a dense, low-growing mat; the flowers may reach a height of between six to eight inches.
English ivy (Hedera helix) is attractive alone or when mixed with other groundcovers such as vinca. It survives winters best when planted near structures or given some protection. 'Baltica' and 'Thorndale' are considered to be the most winter hardy of the many cultivars that exist. Snow cover or a mulch is needed to protect English ivy when grown in exposed sites or colder areas.
Certain flowering perennials also can be used as groundcovers. Lily-of-the-valley (Convallaria majalis) is an excellent choice for light or heavy shade. It spreads by producing underground stems called rhizomes and normally requires about two to three years to cover an area when planted on six-inch centers. Essentially pest free, lily-of-the-valley produces fragrant flowers on small, arching racemes in the spring.
Hosta or plantain lily (Hosta spp.) is well-suited to shady locations under trees or near buildings. Depending on cultivar chosen, leaves may be large or small. Hosta cultivars are available with solid green, blue, yellow or variegated leaves in various color patterns. Hostas are planted mainly for their foliage. However, attractive flowers are produced on scapes at various times of the year, depending upon cultivar. Although hosta leaves die back to the ground during the winter, its spreading roots hold soil in place and prevent erosion.
Daylily (Hemerocallis spp.) arguably is America's most popular flowering perennial. To date, over 70,000 named cultivars have been registered with the American Hemerocallis Society. Daylilies tolerate a wide array of soil conditions and exposures, although flowering is reduced by shade. Vigorous in growth habit, daylilies hold soil well once established making for a very colorful, although somewhat tall, groundcover.
Aggressive growth is an attribute common to most groundcovers. This is understandable since, by definition, groundcovers are plant species that will form a monoculture in an area of the landscape.Â At times, however, some species may become invasive.
Bishop's goutweed (Aegopodium podagraria) is a good example of the latter. It is an excellent groundcover for shady locations with either moist or dry soil. Once established, however, this attractive plant with variegated leaves spreads rapidly and can invade other areas of the landscape. The same is true for houttuynia or chameleon plant (Houttuynia cordata 'Chameleon'), a plant that derives its name from its colorful leaves. Its aggressive growth habit and ability to tolerate a wide array of conditions, makes it a good choice for remote, isolated problem areas in the landscape. Left unchecked, it has the tendency to get out of control very quickly and must be monitored regularly.
Groundcovers should be established in the landscape much the way other perennials are established. Adequate soil preparation through the incorporation of organic matter will help to encourage root growth and ease stress on newly planted groundcovers. This, along with adequate water and fertility, should cause them to establish themselves faster.
Trees with heavy canopies often shed water (especially during light rains) thereby reducing the availability of moisture to plants below. Hence, frequent watering of newly planted groundcovers under trees is needed for rapid establishment. Even after establishment, watering becomes a necessity, especially in periods of dry weather.
The accumulation of leaves is yet another problem for groundcovers under trees to contend with, especially if the trees are large. Groundcovers should never be allowed to be totally covered with leaves. This is especially critical for evergreen groundcovers during the fall and winter. While a thin covering in the winter is not harmful, it should not be so think as to totally block light which evergreen plants need year around.
Finally, while groundcovers tend to choke out competing weeds once established, shade-tolerant weeds can be problematic while the groundcover establishes itself. Mulching between plants as they establish themselves can help prevent weeds. If weeds do appear, they should be removed promptly to prevent them from slowing the development, speed of cover and general attractiveness of the desirable groundcover.
REVISED: February 21, 2017