Groundcovers are low-growing plants that spread quickly to form a dense cover. They add beauty to the landscape, and they can also solve many planting problems in difficult sites. Grass is the best-known groundcover, but grass is not suited to all locations. Other groundcover plants should be used where grass is difficult to grow or maintain. Unlike grass, most groundcover plants cannot be walked on.
Groundcovers are used most frequently for the following locations:
- Erosion control on steep banks or slopes. Grass is often difficult to mow on steep slopes.
- Shady areas under trees and shrubs. When planted under trees, groundcovers reduce mower damage to the base of the tree. Some groundcovers require less sunlight and less moisture and nutrients than grass. Therefore, they are in less competition with trees and shrubs.
- Where tree roots grow close to the surface and prevent grass from growing.
- Very wet or very dry locations.
Selection of a suitable plant for groundcover depends on the area where it will be grown. Some groundcover plants prefer shade. Others thrive in full sun. Some prefer moist soil, while others need dry or well-drained soil. To work well as groundcovers, plants have to be tough, durable, and relatively fast growing but not invasive. Choose plants that are known to do well in the conditions found in your landscape and most importantly guard against plants known to become invasive. That means looking beyond the traditional ivy
(Hedera species) and periwinkle (Vinca minor) that are both known to escape “captivity” and move into natural areas. Vining groundcovers should not be allowed to consume trees since they can choke out sunlight and weigh down branches. For more information on invasive plants see the Invasive Plant Atlas of the United States – http://www.invasiveplantatlas.org/
Because groundcovers live for many years in the same spot, it is worth the effort to prepare the soil well before you plant them. This allows plants to establish good root systems. Perennial weed areas should be cleared before planting groundcovers, since most cannot compete against established weeds.
Improper soil preparation is a frequent cause of groundcover failures. The soil should be worked to a depth of 8 to 10 inches. Incorporate a 2-inch layer of organic matter such as compost or well-rotted manure into the soil to improve drainage in clay soils or to improve the water-holding capacity of sandy soils.
A soil test provides the best guidance for fertilizer usage. In the absence of a soil test, incorporate a complete fertilizer, such as 10-10-10. Mix the fertilizer into the soil to a depth of 6 to 8 inches.
Most groundcovers can be planted at any time of the year. However, fall planting takes advantage of lower temperatures and natural rainfall. Watering is reduced and plants establish a stronger root system before summer. Summer planting requires adequate and frequent watering for survival and establishment.
Space the plants according to their size, the immediate effect desired, and their rate of growth and habit. If the individual plants are spaced too far apart, weeding can be a problem and the time required for complete coverage can be quite long. On the other extreme, planting too closely together can be a needless waste of time, money and plant materials. In addition, there will be increased competition as the plants grow into maturity. Usually, it is best to space the plants so the groundcover areas will, for the most part, be completely covered by the end of the third growing season. A staggered row-planting pattern usually will result in the quickest cover of the planting bed.
Weed control is a must until the groundcover is fully established. A 2-inch layer of mulch will help in the control of weeds. On slopes, coarse netting is also used to hold the slope until the groundcover is established.
It may take up to two years to establish a groundcover area. Fertilizing and watering will probably be required during this period. Apply fertilizer based on how fast you want full coverage to occur. Begin fertilizing 4 to 6 weeks after planting, then make one application in the spring, another during summer, and a third in September. If rapid coverage is desired, make a fourth application during the summer months. A complete fertilizer such as 12-4-8 or 16-4-8 or a similar analysis applied at the rate of 1 pound of nitrogen per 1000 square feet is adequate. To determine how much fertilizer to apply per bed, measure the area of the bed in square feet (length x width). Then, use this equation:
Area of bed divided by 1,000 square feet, divided by the percent of nitrogen in the bag, will give you the amount of fertilizer that needs to be applied to the bed. For example, if the bed measures 200 square feet (20 feet long and 10 feet wide), you can determine that 200/1,000 divided by 12 % (or .12) = 1.6. Therefore, 1.6 pounds of 12-4-8 will need to be applied to this 200-square-foot area.
The next consideration is adequate and timely watering. Water requirements vary with different plants. Groundcover plants should not be allowed to wilt.
Some groundcovers are improved by occasional shearing. Wintercreeper can be clipped at a 4- to 6-inch height. Others, such as dwarf mondograss, can be clipped with hedge shears or mown when they appear shabby. Remove the old growth of mondograss because the leaves harbor fungi, which can disfigure and kill newly emerging leaves. To rejuvenate pachysandra and other herbaceous evergreen groundcovers that have suffered winter burn, use a rotary mower on its highest setting. Early spring is usually the best time to prune groundcovers because new growth will quickly cover the bare stubs. Cut out dead branches and remove winter-damaged branch tips to encourage dense new growth.
Avoid severe pruning in late summer or fall since it can force tender growth that will not have time to harden off properly before winter.
Horizontal junipers like ‘Blue Rug’, ‘Bar Harbor’, and ‘Prince of Wales’ tend to form new foliage on top of older foliage and become thick and dense once their canopies meet. Thinning improves air circulation between the plants and prevents insect and disease problems.
Several fungi and bacteria may cause leaf spots. Infected leaves can be picked off and discarded. Root, stem and crown rots are fungal diseases that are more serious in poorly drained soils. Some groundcover plants, such as ajuga, are very susceptible to root-knot nematodes. Nematodes are microscopic worms that live in the soil and feed on plant roots. Infected plantings will thin out in spots and plants may die.
Recommended groundcovers are listed in the table below.
|Dense evergreen that spreads by underground runners. Effectively crowds out many weeds. The native P. procumbens has marbled leaves and fragrant flowers.||6 to 9 inches||Part to full shade||Prefers moist, fertile, slightly acid, organic soil. Competes well with tree roots. Best in the Midlands and Upstate.|
|Dense, spreading semi- evergreen with soft silver gray leaves.||1 to 2 feet||Full sun||Drought-tolerant. Needs well-drained soil and good air circulation. Will not tolerate excessive moisture.|
|Dark, evergreen leaves. Fragrant white flowers in late spring. ‘Madison’ is a hardy cultivar. T. asiaticum has yellow flowers and is also hardier.||1½ to 2 feet||Part shade||Moist, well-drained soil. Fast growing. When grown for groundcover, clip or mow yearly to keep dense and low.|
|Lustrous, wide-spreading, evergreen with white flowers and small red fruit. Groundcover varieties include ‘Repens’ and ‘Emerald Carpet’.||12 inches||Full sun||Tolerates poor soil and drought. Plant where it will have plenty of room to spread since pruning gives an awkward look.|
|Evergreen, may turn bronze in winter in colder areas. Golden yellow flowers in spring.||Up to 3 feet||Full sun or part shade||Can be used on steep banks to help control erosion. Maintain with a yearly cutting in late spring after flowering.|
|Carpet Bugle, Ajuga
|Green, purple or variegated evergreen leaves. Blue flowers on spikes in spring. Spreads quickly.||6 inches||Full sun to part shade||Mow after flowering to remove stems and tidy up appearance. May become invasive in turf.|
|Cast Iron Plant
|Long, tall, dark evergreen leathery leaves. There is a white-edged variety.||1 to 2½ feet||Part to very deep shade||Will live in difficult situations, in almost any soil. Does best in mid-state and coastal areas.|
|Deep blue flowers in late summer. Foliage turns reddish in fall and winter. Spreads underground.||6 to 12 inches||Sun or light shade||Prefers moderately fertile, well-drained soil. Good bulb cover. Mow to ground in late winter.|
|Blue green to gray green needlelike evergreen foliage covered by very fragrant white or pink flowers in spring.||9 to 12 inches in bloom.||Full sun||Well-drained soil. Do not overwater. Trim after flowering. This species is the most tolerant of heat and humidity.|
|Needled evergreens with many cultivars and species of varying foliage color, texture, height and form.||Height varies by cultivar||Full sun||Well-drained, moderately dry soil. Shore juniper tolerates seashore conditions.|
|Tiny needlelike, evergreen foliage is covered by pink, rose, lavender or white flowers in early spring.||6 inches||Full sun||Well-drained soil that is not overly rich. Shear lightly after flowering is finished.|
|Clumps of evergreen or semi-evergreen heart- shaped leaves with dainty crimson, yellow or white flowers in early spring.||6 to 18 inches||Shade or part shade||Prefers moist, well-drained soil, but will tolerate growing in amongst tree roots. Cut back in late winter.|
|Green and Gold
|Starry, yellow flowers in spring.||4 to 12 inches||Part shade||Prefers average soils, adequate moisture.|
|Evergreen, leathery and glossy dark-green leaves. Spreads moderately.||1½ to 2 feet||Shade||Well-drained, slightly acidic, moderately moist soil with high organic matter.|
|Large, soft furry gray leaves are topped with spikes of purple flowers in late spring.||6 to 8 inches in leaf, 18 inches in flower||Full sun to high open shade||Well-drained soil. ‘Silver Carpet’ does not flower. ‘Big Ears’ is most tolerant of humidity.|
|Rapid-growing with a long bloom season. Flowers are often multi-colored, yellow, red and orange. Pink, lavender and white are also available. All attract butterflies.||Shrub lantanas to 3 feet; creeping lantana to 12 to 18 inches||Full sun||Well-drained soil, drought-tolerant when mature. Will grow well near the beach. Do not overfertilize. Prune back hard in spring to remove dead wood. Best in mid-state and coast. ‘Miss Huff’ is hardy in Upstate.|
|Dark green leaves turn yellow in fall. Fragrant, white, bell-shaped flowers.||8 inches||Shade||Prefers moist, fertile, organic soil. Spreads vigorously by underground rhizomes.|
|Evergreen, grass-like leaves similar to liriope, but more slender.||4 to 12 inches||Sun or shade||Prefers moderately moist soil, Low maintenance once established. Trim or mow in early spring.|
(Rosmarinus officinalis ‘Prostratus’)
|Evergreen, with aromatic, needlelike foliage. Pale blue flowers in spring.||12 to 36 inches||Full sun||Requires very good drainage. On heavy, clay soil, it is more susceptible to winter damage.|
|Low mounded evergreen shrub, with fine-textured gray-green foliage. Tiny yellow flowers in June.||1 to 2 feet||Sun||Well-drained soil. Avoid frequent watering. Can be sheared.|
(Sarcococca hookeriana humilis)
|Low, creeping evergreen. Tiny, sweetly scented flowers in winter.||12 to 15 inches||Light to heavy shade||Moist soil amended with plenty of organic matter.|
|Trailing, fleshy deep purple stems and leaves with lavender to purple flowers.||1 to 1½ feet||Shade or sun||Purple heart thrives in heat and drought conditions. In colder parts of the state, the top freezes in winter but it resprouts from the roots.|
|Spreading shrubby evergreen or semi-evergreen with bright yellow flowers in mid-summer.||1 to 3 feet||Full sun or part shade.||Well-drained soil. Excellent for covering slopes. Cut to ground level in spring to rejuvenate.|
|Upland River Oats
|Upright, native perennial grass with attractive seed heads and yellow fall color. Seeds provide winter interest.||2 to 4 feet||Full sun to part shade||Prefers loamy, well-drained soil but adapts to even poorly drained soils. Great for stabilizing soils on banks. Very low maintenance, simply cut back in late winter as new growth emerges from base. Will reseed.|
|Native perennial grass with attractive pink flowers in mid to late summer. Offers great winter interest.||1-3 feet||Full sun||Well-drained soils. Cut back in late winter to early spring when new growth emerges from base.|
|Autumn fern (Dryopteris erythrosora||Evergreen fern with interesting copper-bronze color appearing on new foliage.||1-3 feet||Part sun to full shade||Low maintenance, low moisture requirements.|