By Joel M. Lerner
Saturday, January 21, 2006
Raindrop splash, the top cause of garden soil erosion, can be stopped only by plants that grow close to the ground -- called, of course, ground covers.
If you have enough sun, lawn is usually the choice to keep your topsoil in place. In shade, a ground cover that thrives in low light is better. Even in sunny areas, homeowners need alternatives to turf, especially on steep slopes.
Plants ranging from four inches to four feet in height that will mass together to form a mat make useful ground covers. Some are chosen for ornamental characteristics, but all must grow vigorously. Those that are aesthetically pleasing and hearty make the most desirable carpeting for your property.
If chosen properly, a lush, almost maintenance-free carpet of plants will grow. They can offer fragrance, flowers, berries and colorful foliage. They can also help control weeds naturally. Any vigorous low-growing plant that persists year after year and drops leaves or needles to add organic material is an excellent candidate.
Listed below are 20 practical ground covers -- 10 for full to partial sun and 10 for partial shade to shade.Full to Partial Sun (More Than Six Hours a Day)
· Arnold dwarf creeping forsythia: Any soil. Excellent bank cover, yellow spring flower, can display good fall color. Install plants on three- to five-foot centers.
· Winter-flowering jasmine (Jasminum nudiflorum): Grows quickly, with prostrate, arching and cascading stems that root wherever they touch the ground. Stems stay green in winter. Yellow flowers open sporadically throughout winter. If plants get too large after several years, cut to the ground before growth begins in spring. Plant at least three feet apart.
· Blue rug juniper (Juniperus horizontalis "Blue Rug"): The ultimate in prostrate plants, blue stems that hug the ground and creep up to eight feet in diameter. Good for holding slopes. Plant three to four feet apart.
· Blue star juniper (J. squamata "Blue Star"): Slow-growing, low habit, drought-tolerant blue foliage, will create a billowy, blue, evergreen carpet that persists year round. Plant two to three feet apart. Grows up to three feet tall.
· Compact andorra juniper (J. horizontalis "Plumosa"): Tolerant of most soils and ocean air. Low-massing shrubs, to 18 inches, with a feathery, upright appearance. Turns light purple in winter. Plant these evergreens three feet apart.
· Flowering ground-cover roses: Grow from three to four feet tall, bred to be long-blooming, spread to cover the ground, do well in most soils, discourage cats and dogs, but deer will eat them. Available in white, red and pink, may cut back at end of season. Plant three feet apart.
· Plumbago (Ceratostigma plumbaginoides): Moist, well-drained soil a necessity, full eastern exposure, protect from hot afternoon sun. Flowers deep blue in summer, red fall foliage, dies back in winter. Late to leaf-out in spring. Plant eight inches apart.
· St. John's wort (Hypericum calycinum): Any soil. Blue-green foliage, invasive rhizome habit, yellow flowers in summer, deciduous sub-shrub. Plant two feet apart. Good wildlife-resistant ground cover.
· Snow-in-Summer (Cerastium tomentosum): Well-drained soil is best. Silvery-green foliage, dense low grower, white flower spring and early summer. Plant 12 inches apart. Cascades over low slopes and walls. Protect from the hottest sun.
· Weeping willowleaf cotoneaster (C. salicifolius "Repens"): Moist, well-drained soil. Vigorous prostrate shrub with arching branches and maroon fall foliage that holds through winter. Plant three feet or more apart.Partial to Heavy Shade (Less Than Six Hours of Sun a Day)
· Lily-turf (Liriope muscari hybrids): Grows in most types of soil. This 12-inch-long, clump-forming, evergreen with grassy foliage is a good hedge against erosion. Some have variegated foliage. Plant 12 to 18 inches apart.
· Pachysandra: Moist, well-drained humus. Evergreen, handsome new growth, fragrant, white flower in spring, transplants easily and is available in 2 1/2-inch pots or cells ready to plant. Creates beautiful drifts that hold their foliage dependably through winter. Plant eight inches apart to grow full in three to five years.
· Periwinkle (Vinca minor): Likes moist, well-drained humus. Has blue, lavender or white flowers in spring, fine textured, dark-green, evergreen foliage. Usually available in 2 1/2-inch pots or cells, space six to eight inches apart, depending on how fast you want total coverage.
· Lungwort (Pulmonaria): Outstanding in early spring. Depending on the species, flowers in red, purple, white or blue and foliage shows silvery spots, splotches or white variegations. Growing eight to 12 inches tall and about 18 inches wide, they cover the ground in several seasons. Some display small leaves with silver spots, long leaves with large, silver splotches; others have green foliage.
· Sweet box (Sarcococca hookeriana var. humilis): Loves moist, well-drained humus. Has handsome thick, dark green leaves. Its minute flowers in April drench the air with fragrance. This low-growing evergreen shrub is slow to establish but tough and long-lived. Plant one to two feet apart.
· Tiarella: Moist, well-drained humus. Leaves are green, some show a silver margin, magnificent in large drifts of spring flowers, and forms colonies eight to 12 inches tall. Plant eight to 12 inches apart.
· Woodland phlox (P. divaricata): Colonizes into a deep-green foliaged planting growing 12 to 15 inches tall with lavender, blue or white flowers in spring. Blends well with other woodland plants, striking interplanted with tiarella. Beautiful fall color. Install plants 12 inches apart.
· Lenten rose (Helleborus orientalis): Evergreen perennial, flowers in February, many new hybrids from white and pink to maroon, large leaves offer coarse texture in dense shade. Will grow into herbaceous, two to three feet high and wide shrubby plant throughout the growing season. Not eaten by wildlife. Plant on two-foot centers.
· Rohdea: Looks like a houseplant, member of the lily family, strap-shaped leaves stay green 12 months a year in the shade and grow slowly into colonies, densely covering the ground in the heaviest of shade. Wildlife does not eat this plant.
· Astilbe pumila: Grows into a mass on the edge of moist shade, making a superb eight- to 16-inch-tall ground cover with purple/lavender spikes above the foliage of this dainty-looking, but surprisingly good ornamental hedge against erosion.Maintenance Workload Diminishes With Time
Leaving an area to nature will also result in plants covering the ground. They will do it through self-seeding and with the help of animals. The forest is one example. It covers itself with leaf mulch annually, and up to 150 species of plants will begin growing in an average acre. Cleared fields also automatically become covered with a wide mix of plants, which will with time become a forest just by letting nature take its course. You have the option of managing a naturally occurring garden in any way you wish, but it will need managing. Otherwise, one invasive plant could dominate your property.
Most ground covers suited for residential properties are planted as rooted cuttings or seedlings. They are more labor-intensive to install than spreading seed, but many of the most desirable ground covers would take far too long to grow from a sprout. They may not even produce seed in this region.
When establishing plantings, water thoroughly at time of planting and during dry periods. Weed as necessary.
Installing ground cover usually requires planting lots of stock. Use the following information to figure how many plants you'll need to cover the area you are planting:
· Planting eight inches apart: Install 150 plants per 100 square feet.
· Planting 12 inches apart: Install 100 plants per 100 square feet.
· Planting 18 inches apart: Install 45 plants per 100 square feet.
· Planting two feet apart: Install 25 plants per 100 square feet.
· Planting three feet apart: Install 11 plants per 100 square feet.
You can look forward to a diminishing workload of weeding and mulching as the plants grow together over two to five years.
Joel M. Lerner is president of Environmental Design in Capitol View Park, Md. E-mail or contact him through his Web site,http://www.gardenlerner.com.