The thick clumps of evergreen grass-like foliage of mondo grass, Ophiopogon japonicas, make a nice lumpy ground cover for small spaces. Because it is rather tolerant of shade, and actually prefers partial shade to full sun, it works nicely under Japanese maples or highly branched overgrown rhododendrons. It gets only about half a foot deep. Narrow stems with small pale purplish blue flowers that bloom in summer are not too abundant, and are generally obscured below the foliage, but can actually get taller. ‘Silver Mist’ is variegated with white.
New plants are easily produced by division of large clumps. Overgrown or tired looking clumps can be shorn down at the end of winter, before new growth begins. Slugs and snails can be problematic.
It is not actually moss. It is of the same family as carnation. Of course, any distinguishing characteristics of its family are difficult to recognize. Iris moss, Sagina subulata, has such exceptionally fine foliar texture and diminutive bloom. Its slim leaves are not much longer than a quarter of an inch. its tiny white flowers are barely wider than an eighth of an inch.
Irish moss is a luxuriantly dense and richly evergreen ground cover for confined spaces. It works well within small atriums and big pots that contain sculptural plants that lack low foliage. It is a popular accessory for Japanese maple and citrus within tubs. Since it gets no more than two inches deep, Irish moss can fill in between pavers and under benches.
However, Irish moss dislikes how pavement enhances harsh exposure. Although it does not require shade, it appreciates a bit of partial shade while the weather is warmest after noon. Also, it craves somewhat frequent watering to compensate for locally arid warmth. Scottish moss is the cultivar ‘Aurea’. It is lighter chartreuse green, but otherwise identical.
Within the outdoor rooms of home gardens, shade trees are ceilings, shrubs and hedges are walls, and turf and ground cover plants are floors. That is why the selection of plants for such purposes is as important as the selection of paint and carpet for indoors. Among ground cover plants, durable turf grasses for lawns are the most common and functional.
There are so many more types of ground cover plants besides turf grasses though. A few of the lower, denser and more resilient types of ground cover plants can function as turf if necessary. Many more function as mulch to control erosion, contain dust or conceal mud. Many inhibit proliferation of weeds. Some retain a bit more moisture than they consume.
Appropriate ground cover plants most definitely have many advantages. They also have certain disadvantages. Although most require less maintenance than the weeds that they exclude, they require more maintenance than simple mulch. Also, most require irrigation. They might be trailing perennials, sprawling shrubbery, or unsupported wandering vines.
Trailing gazania, Hottentot fig (freeway ‘ice plant’) and various ice plants are some of the more popular perennial ground cover plants. They and others migrate by trailing stolons or rhizomes. They are among the lower and more compact types of ground cover plants. Some need no more pruning than edging. Many propagate easily by division or cuttings.
Sprawling sorts of juniper, ceanothus, cotoneaster, myoporum and rosemary are shrubby ground cover plants. They get significantly deeper than perennial plants, and some sorts can eventually get too overgrown to be practical. Rosemary, myoporum and cotoneaster are conducive to shearing as they mature. Ceanothus and juniper need significant area.
English ivy, Algerian ivy and star jasmine are vining ground cover plants that should stay rather low if properly maintained. However, they can climb into shrubbery and trees, and even buildings. The ivies are famously aggressive, and spread indefinitely by rooting as they migrate. Severe pruning can renovate some overgrown vining ground cover plants. Bougainville gets rather shrubby and deep, even without support.
This is not the genuine licorice of confectionery. This more popular home garden licorice plant, Helichrysum petiolare, is more of an ornamental plant than a culinary herb. Its mild foliar aroma resembles that of genuine licorice, but is very faint. Without disruption of the foliage, the aroma is imperceptible. Since the foliage can be toxic, the flavor is irrelevant.
Licorice plant is popular for its appealingly silvery foliage. Some cultivars are variegated. ‘Limelight’ is strikingly pale silvery chartreuse. The small, rounded and evergreen leaves are distinctly tomentous (slightly fuzzy). The sprawling stems tend to disperse over older growth, and might get deeper than a foot and a half. Mature plants get wider than six feet.
Licorice plant is susceptible to extremes of temperatures. Within more severe climates, it appreciates a bit of partial shade during excessively warm and arid weather. Foliage can roast from harsh exposure. Where winters are cool, foliage appreciates shelter from frost. Roots are susceptible to rot with excessively frequent watering, or inadequate drainage.
Parkstrips, those narrow spaces between curbs and sidewalks, are among the most awkward spaces in the garden. In urban areas with significant traffic, they are commonly paved over. Some neighborhoods, especially downtown neighborhoods, do not have parkstrips at all. Suburban neighborhoods though, often have wider parkstrips.
The difficulty with parkstrips is that there is so much happening around them. Cars get parked on one side. Pedestrians pass by on the other side. Driveways need to be kept clear at each end. Water meters and perhaps other subterranean utilities must be accessible.
Street trees are common features in parkstrips. They should have complaisant roots that will be less likely to displace the surrounding pavement and curbs, and high branch structure for adequate clearance above truck traffic on the roadways below. Ideally, street trees should conform with the neighborhood, and are often quite uniform. Selection of street trees should be a community effort where practical.
All other plants that go into parkstrips should be adaptable to confinement within the limited space available. They should not extend over curbs or sidewalks where they can scratch parking cars or be obtrusive to pedestrians. Parkstrip landscapes must also stay low enough so that they do not obstruct the view from cars backing out of driveways.
Because people regularly walk past or through parkstrips, thorny plants like cacti and roses should be kept back from the edges, or preferable not put into parkstrips at all. Large agaves and yuccas (with rigid leaves) are simply too big and dangerous for narrow parkstrips.
Contrary to the trend of planting vegetables in weird places, parkstrips are not good places for them either. The main problem is what dogs like to do in parkstrips. The second problem is that the good produce that might be out reach of dogs is within reach of everyone else walking or driving by. Reflected glare from all the surrounding pavement is a problem for plants that do not like harsh exposure.
Really, there are far more limitations on parkstrip landscaping than there are options. Turf grasses or tough ground cover that tolerates traffic, like trailing gazania, may seem to be a mundane, but they are practical. At least ground cover can be punctuated with clumping perennials like African iris, lily-of-the-Nile or blanket flower.
Only a few decades ago, the only familiar African daisies, Osteospermum spp., were the sprawling and often sparsely branched ‘freeway daisies’ with blue-eyed white or rarely light purple flowers. They made nice blooming ground cover that could be planted in drifts for a bit of color among the deep green of Algerian ivy on expansive freeway embankments.
Modern varieties are shrubbier perennials with more profuse bloom of white, cream, pink, purple, pale yellow or pale orange flowers, mostly with blue or purple centers. Some yellow flowers have yellow or cream centers. Some of the fancy types have spooned petals like some types of cosmos or chrysanthemums. After the primary bloom phase in spring, a few sporadic flowers may continue to bloom through summer until the secondary light bloom phase late in summer. However, the old fashioned ‘freeway daisy’ types do not always display a second bloom phase. Varieties with variegated foliage are still rather rare.
Even though African daisies can survive in inferior soil with minimal watering, they perform best with good soil and regular watering. Plants in containers can not disperse their roots like they want to, so are are more dependent on regular watering. Fertilizer prolongs bloom.
Coprosmas are so innately undemanding and complaisant to all sorts of conditions, that some types self sow and thrive untended in riparian or coastal environments. If they were more aggressive, they would likely naturalize (proliferate as if native) where the soil does not get too dry through summer. With such glossy foliage that looks like plastic, they might be appealing weeds.
Coprosma X kirkii is a resilient ground cover that mostly stays less than two feet deep and five feet wide, although overgrown plants can get three feet deep. Varieties with colorful or variegated foliage probably stay too small to be reliable ground cover over large areas, but make nice edging, or can cascade nicely from raised planters or urns.
Of all the functions that the many and various plants in the garden serve, ground covers have the lowliest job description. Well, maybe it is just the lowest job; covering the ground. It is an important job though. Ground covers fill in the space between other desirable plants to obscure otherwise bare soil. They also control weeds. Some ground covers help to limit erosion. Others help to insulate the soil for plants with sensitive roots.
There certainly are all sorts of ground cover. Lawns are the most familiar. Many other ground covers are perennials like gazanias, African daisies and iceplants. Some, like ivies, honeysuckles and star jasmine, are vines. Others are low growing shrubs like certain coprosmas, cotoneasters and junipers. Some lay about as flat as carpeting. Some get a few feet deep.
Many perennial ground covers as well as some of the vines and low growing shrubbery provide colorful flowers. Japanese honeysuckle and star jasmine are not as colorful, but provide delightful fragrance. Some of the cotoneasters have colorful berries in winter. Although not seen, many ground covers are appreciated more for their network or roots that help to stabilize soil that might otherwise erode. One feature that most ground cover plants have in common though, is their foliage that is dense enough to keep weeds out, as well as to obscure the soil below.
Like all other plants in the landscape, ground cover plants need maintenance. Lawns probably need more maintenance than any other ground cover, since they need to be mowed, weeded, fertilized and watered quite regularly. Vine ground covers need to be pruned so that they do not get into trees and shrubbery. Some ground covers look best if mowed annually (typically at the end of winter) or even more frequently. Some of the deeper ground cover shrubs should be pruned down to stay low. Almost all ground covers need to be edged for confinement.
Ground cover plants must be selected for their appropriateness to particular applications. For example, most low growing shrubbery needs space, so is best for larger areas. Smaller iceplants that may not be aggressive enough for big areas are great for tight spots, or for mixing with other perennials. Tough Algerian ivy that is so useful for freeway embankments may be too aggressive for home gardens. As with all plants in the garden, careful selection helps to get the best ground cover plants for each particular situation where ground covers are needed.
Cats prefer catnip. It makes better tea too. Catmint, Nepeta X faassenii, is prettier though. It sprawls over the ground to get about three feet wide, without getting more than two feet deep. Where well exposed, it may not get much deeper than one foot. The aromatic gray foliage is denser than that of related catnip. Its individual leaves are small and furrowed.
Bloom begins with warming spring weather, and continues until cooling autumn weather. Individual flowers are tiny, and suspended on small floral stems. They just happen to be very abundant. Warmth stimulates phases of exceptionally profuse bloom. Floral color is light or pale blue, like faded denim. Shearing to deadhead enhances profusion of bloom.
Catmint works well as a rustic border or a ground cover for small areas. Alternatively, the blue bloom can be a delightful component of mixed perennials, in beds, planters or pots. Deer generally ignore catmint. Bees most definitely do not. They swarm it! ‘Walker’s Low’ is the most popular cultivar. It may be all that is available in some regions. Catmint is sterile, so generates no seedlings.
All flowers that need help with getting pollinated do what they can to attract pollinators. The tiny flowers of lantana, Lantana camara, actually put forth a bit of extra effort to improve the efficiency of their pollinators, by becoming less attractive once pollinated. Within each tightly set flower cluster, pollinated flowers fade to an alternate color to inform pollinators that their services are no longer needed. This prioritizes flowers than still await pollination. Consequently, each small cluster exhibits flowers of two different colors. The choices are red, orange, yellow, pink, purplish pink or white.
The small and aromatic leaves are arranged in alternating pairs on thin stems that do not get much higher or wider than three feet. Established plants can survive with very minimal watering, but bloom better with somewhat regular watering. The summer bloom is very attractive to butterflies.
Trailing lantana, Lantana montevidensis, has limber stems that sprawl a few feet over the ground without getting a foot deep. It cascades nicely over retaining walls or from large planters. Flowers are shades of lavender, or sometimes white.