Any plant that carpets the ground with foliage, stays under 12 in (30.5 cm) in height, and grows so thickly that it naturally chokes out weeds qualifies as a groundcover. If you think of lawn grass as only one type of groundcover, it becomes easier to imagine using.other plants to replace patches of turf in parts of your landscape.
Dozens of plants, including shrubs, ornamental grasses, perennials, and herbs, make hard-working groundcovers when planted in a site that allows them to spread into broad mats of foliage. They require less water and care than lawn grass, making them excellent choices for arid regions and gardeners who want low-maintenance landscapes. A few shrubs commonly used as groundcovers, including cotoneaster, also produce berries, and a number of spreading perennials, such as bugleweed and lamb's ears, add flowers to the show.
There are basically two types of groundcovers: deciduous, which loses its foliage in winter, and evergreen, which retains its foliage year-round.
Deciduous groundcovers, when planted in broad bands or drifts, are a great way to fill small nooks that are difficult to mow. Or you can use them to cover difficult slopes, bring lively color to shade, or put them to work as a visual transition between lawn and paved areas. Deciduous groundcovers require a tittle more attention, because they cannot shade out weeds year-round the way evergreens do, but they still demand less upkeep than a grass lawn.
Groundcovers that are evergreen or semi-evergreen, meaning that they retain their foliage except in the coldest winters, work all year in partnership with your lawn or in place of it. Where winters are very cold, your choices may be limited to spreading juniper or English ivy, but gardeners in mild-winter climates have many more choices.
Sun-loving shrubs that spread into care-free ground-covers include low-growing cultivars of: cotoneaster, juniper, and euonymus.
Shade-loving perennial groundcovers include asarum, hellebore, dead nettle, lungwort, epimedium, sweet, woodruff, and fern.
Where at least a half day of sun is available, select from among these perennials bugleweed, creeping phlox, dianthus, thyme, lamb's ear, and spreading veronica.
For long-term success with fast-growing perennial groundcovers, take the time to prepare the planting site well, as plants will be living in their new home for many years. Dig the soil at least 6 in (15 cm) deep and mix in compost or other organic matter to improve the texture, or build a shallow berm of improved soil. When setting out slow-growing groundcover shrubs, however, prepare individual planting holes in unimproved soil, because cultivating soil unnecessarily often triggers an explosion of germinating weed seeds.
Make sure you have enough plants, which may be more than you think. Perennial groundcover starter plants are usually planted 6-12 in (1S.2-30.5 cm) apart in all directions, and closer spacing results in faster coverage. When planting a large area or a steep slope with spreading shrubs, it is often wise to stretch a sheet of landscaping fabric over the prepared soil, then cut holes in it where you need to set in the plants. When finished, top with 3 in (7.6 cm) of an ornamental mulch, such as shredded bark or bark chips. Besides suppressing weeds, this "double mulch" retains soil moisture. After planting, irrigate groundcovers as needed to keep the soil moist the first season to help them become established.
While groundcovers are filling in, you can sprinkle a pre-emergent herbicide, which prevents weed seed from sprouting, on the soil around them. It will not harm groundcover plants, as this product only affects seeds. Even so, some hand weeding is usually necessary before plants start to spread. Pull out weeds when they are young, so that you disturb the soil as little as possible and prevent the weeds from robbing water and nutrients from the groundcover. After two seasons, the weed population will drop sharply as the groundcovers take over, blocking the tight that weeds need to grow.
Groundcovers can do a much better job of blanketing the ground when they are adequately fertilized. In early spring, spread a balanced, commercial, slow-release or organic fertilizer at the rate recommended on the package. You can also spread 2 in (5.1 cm) of compost or well-rotted manure.
Watch for signs of trouble. Tiny, stationary tan or brown discs attached to plant stems are a sign of scale, which is not an unusual insect pest to discover lurking in groundcovers. Trim back badly infested stems and destroy the dippings. You can treat moderate outbreaks with commercial dormant oil or a pesticide labeled for use on the plant species with the scale problem. Use according to label directions.
Just as grass requires routine mowing, ground-covers often need regular edging and cutting back. Hard edging materials, such as bricks or flat stones, can reduce the frequently of this chore, but you may still will need to use pruners, garden shears, or a mower to keep spreading groundcovers from moving into areas where they are not wanted.
If, after a hard winter, your groundcover plants have brown and tattered foliage, you can renew them in early spring by cutting them back nearly to the ground using a string trimmer or mower set at a high setting. Within a few weeks, they will produce fresh, healthy new foliage.
Rejuvenating Old Plantings
After several years, some groundcovers become so crowded and overgrown that their health deteriorates. The method of rejuvenation depends on the type of plant you are growing. Flowering perennials often need to be dug and divided, and shrubs, except for juniper, can be pruned back severely. Some spreading groundcovers, such as liriope, can be sheared back to 4 in (10.2 an) with a string trimmer or a mower with its blade set at its highest setting in late winter or early spring. Rake out the debris and then apply fertilizer and a 2 in (5.1 cm) layer of an organic mulch. By early summer, the planting should be covered with fresh new growth.
Vigorous and durable, evergreen groundcovers are top plants for framing a lawn, masking the bases of trees, or planting on slopes. They usually cannot withstand foot traffic, but they do an excellent job of edging walkways or other hard surfaces provided you are willing to. trim them back from time to time. You can also put them to work near deciduous shrubs or combine them with spring-flowering bulbs. Some
of the most popular, effective, and care-free evergreen groundcovers are listed here.
Ivy (Hedera spp.)
English ivy (Hedera helix) has a well-deserved reputation for growing with such exuberance that it climbs trees and buildings, sometimes overwhelming them. However, when planted as a groundcover and trimmed two or three times a year to keep its edges neat, English ivy is well behaved. The same can be said of English ivy's large-leaved and tender cousin, Algerian ivy (H. algeriensis), which grows from Zones 8 to 10. Because they are so persistent and deeply rooted, these ivies are the best evergreen ground-covers for planting beneath trees that have extensive surface roots.
The best varieties for groundcover use have broad, dark green foliage, not small, divided "bird's foot" leaves. These and the types that have variegated leaves are nice for filling small areas in shady places and growing in containers, but they seldom give the thick coverage needed to control weeds.
Every 6 weeks or so, check to make sure that the ivy is not growing' on trees. If it is already clinging to the trunks, pull off the stems and trim them back to about 6 in (15.2 cm) from the base of the tree. Fertilize ivy lightly in early spring with a balanced commercial fertilizer, such as 10-10-10, applied according to package directions, and shear back plantings damaged by severe winter weather.
Few pests or diseases other than sap-sucking scale insects bother established ivy. Control these pests by spraying commercial dormant oil as directed on the package label. Leaves are sometimes infected with fungal diseases that cause them to develop spots before turning yellow and dropping off. This does not require treatment, because the leaves are quickly replaced by vibrant new growth.
Liriope (Liriope Muscari, L. Spicata)
Often known as lily turf, this easy-to-grow ground-cover has handsome grasslike foliage and purple flower spikes in late summer. The most common species, blue lily turf (Liriope muscari), grows into bigger and prettier clumps year after year. Creeping liriope (L. spicata) spreads via short creeping stems, so it is the best type for covering a large space. Plant liriope in broad bands or use it as an edging between the lawn and a shrub bed or foundation grouping.
Plant liriope 6 in (15.2 cm) apart; it usually fills in within 2 years. Liriope seldom needs fertilizing, but it does look better in spring if the old leaves are trimmed off before the new growth begins. In late winter, use hedge clippers or even a lawn mower set at the highest setting to remove the winter-ravaged leaves just above the plants' crowns.
You can dig and divide liriope to increase your supply, but it is not necessary for plant health. Few pests or diseases ever bother these plants.
Pachysandra (Pachysandra Terminalis)
Pachysandra, also commonly known as Japanese spurge, demands a shady site, soil of average fertility, and regular moisture. When given the conditions it prefers, pachysandra is truly the queen of evergreen groundcovers, willing to spread into an ankle-deep blanket of green whorled leaves. Variegated forms are not as vigorous as the green-leaved types, but they are beautiful when put to work filling in between azaleas, rhododendrons, and other shade-tolerant shrubs.
Before planting pachysandra in spring, work in a 3 in (7.6 cm) thick layer of compost or rotted manure. Set plants 6 in (15 cm) apart and mulch between them to help keep the soil moist. Fertilize established plantings in spring and midsummer, using an organic or balanced, controlled-release fertilizer, such as 5-10-10. A soaker hose, snaked between the plants, and concealed by them, is the easiest way to provide water during dry spells.
In fall, be sure to rake off fallen tree leaves. They promote damp conditions that can lead to problems with leaf blight, a fungal disease, which makes the leaves turn black. Treat badly affected areas with a fungicide labeled for use on pachysandra, applied according to package directions. If harsh winter weather leaves pachysandra foliage ragged and yellow, trim back the top 2 in (5.1 cm) of foliage first thing in spring. This will help force out new branches, restoring the handsome blanket of green.
Periwinkle (Vinca spp.)
Periwinkle features glossy, dark green or variegated leaves and starry blue flowers in spring. This vining groundcover spreads by sending out long stems that develop roots wherever they touch the ground. It is an excellent choice for growing on slopes or beneath large shrubs and can be planted with small daffodils and other spring bulbs. Vinca minor is hardy to Zone 4 and stays evergreen even in cold climates. A larger
cousin, V. major, is hardy to Zone 7 and makes a taller, coarser-looking groundcover.
Periwinkle requires at least partial shade and will turn yellow or simply refuse to grow in searing sun. When planted near walkways or other hard surfaces, it needs regular trimming to keep the edges neat. This is a wonderful groundcover to grow beneath deciduous trees, as it cannot climb up tree trunks the way ivy does. However, you will need to gently rake off leaves in fall, because periwinkle thrives on winter sunshine.
Set out plants in spring, spacing them 12 in (30.5 cm) apart. Expect two years to pass before the groundcover fills in. Except for a tendency to become invaded by weeds, such as tree seedlings, care-free periwinkle rarely suffers from pest problems.