African Daisy

Modern African daisies are surprisingly colorful.

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.

Coprosma X kirkii

Variegated Coprosma X kirkii has very glossy light green leaves with white margins that look great cascading over retaining walls.

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.

THE LOWDOWN ON GROUND COVER

Most euonymus are upright shrubbery. This one though, stays low enough to be useful as a shallow shrubby ground cover.

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.

Catmint

Catmint bloom is like faded denim.

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.

Lantana

Lantana sports two colors per bloom.

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.

Creeping Thyme

Creeping thyme is pleasantly aromatic, but not quite as flavorful as culinary thyme.

Trendy landscape designers like to set flagstone walkways slightly out of step to compel visitors to the garden to stroll through a bit slower. Between the stones, it is in style to grow creeping thyme, Thymus spp., as a very shallow groundcover that relinquishes its delightfully herbal aroma with any misstep. It stays too low to trip on, tolerates a bit of trampling, and needs only minor trimming where it creeps a bit too far onto stones or pavement. Creeping thyme can also be plugged into retaining walls of broken concrete or stone. The grayish green foliage is very finely textured. While the weather is warm, minute lavender flowers bloom in subdued phases that come and go slowly. Some varieties have more pinkish flowers, lighter green foliage or exhibit different aromas.

Knotweed

Knotweed by any other name. . .

There are no fancy varieties, but many different fancy names for knotweed. It used to be known as Polygonum capitatum, but is now easier to research as Persicaria capitata. The many common names include pink knotweed, pink clover, pink fleece flower, pinkhead, pink bubbleweed and smartweed. Obviously, the tiny and spherical blooms are pink, about the color of bubble gum. Each small leaf has a distinctive brown chevron, which makes the collective foliage rather bronzy. The wiry stems can not stand much more than three inches high, but creep indefinitely, rooting as they go. Knotweed is an excellent but potentially invasive groundcover, and is also a nice component to mixed plantings in large urns or behind retaining walls, where it can cascade several inches over the edges. A bit of partial shade is no problem. Bloom continues through the end of summer, and resumes at the end of winter.

English Ivy

Rampant English ivy can overwhelm trees.

Compared to Algerian ivy, English ivy, Hedera helix, may seem to be more complaisant. As ground cover, it mostly stays a bit lower, with smaller leaves, and a more refined foliar texture. It is generally easier to maintain and to mow if it does not get too deep. However, where it naturalizes, English ivy is more aggressive and more invasive than Algerian ivy. 

If contained, English ivy is a splendidly dense and evergreen ground cover that excludes most weeds. Containment is very important! English ivy must not climb into shrubbery or trees. It otherwise overwhelms its support and disperses seed. Although reasonably safe on bare concrete walls, it ruins wooden, painted and stucco surfaces. Growth is very fast! 

‘Hahn’s’ is likely the most popular cultivar of English ivy. It branches well, to fill out fast as ground cover. Cultivars that are variegated with white or yellow grow significantly slower, but provide elegant foliage for big pots or planters of mixed annuals or perennials. Foliar lobes are variable. For example, lobes of ‘Needlepoint’ are distinctly narrow and pointed.

Ground Cover Works Like Mulch

Ground covers, simply speaking, cover ground.

Weeding otherwise bare and unused ground is no fun. Nor is weed whacking. Mulching inhibits future weed growth, but requires occasional replenishment. For many situations, ground cover plants are more practical. Once established, many sorts effectively exclude most weeds. Even more contain dust, and inhibit erosion of the surface of the soil below.

As the terminology implies, ground cover plants are simply plants that disperse laterally, over the surface of the ground. Many migrate by subterranean stems known as rhizomes, or by stems on the surface of the soil, known as stolons. Some are vines that behave like stolons. Also, many are merely prostrate shrubbery that does not stand upright very high. 

Ground cover plants generally require more maintenance than mulch, and most want for some degree of irrigation. Conversely they require less effort than weeding. Furthermore, ground cover plants can live on slopes that are too steep for mulch to adhere to, and are more appealing than mulch. They might be as colorful or fragrant as other sorts of plants. 

Prostrate shrubbery, such as creeping cultivars of juniper, manzanita and ceanothus, are best in areas that are big enough to accommodate their width at maturity. Within confined spaces, they need pruning around the edges, which exposes unappealingly bare interior stems. Prostrate shrubbery generally gets higher than other types of ground cover plants. 

The many vines that work as ground cover probably stay lower than prostrate shrubbery, unless of course they climb into bigger shrubbery and trees. Algerian ivy and English ivy are famously aggressive if they overwhelm other vegetation. Also, they can cling to walls and ruin paint and siding. Star jasmine climbs too, but does not cling, and is more docile. 

Perennial ground cover plants, such as various iceplant, trailing gazania, trailing African daisy and pigface (freeway iceplant), tend to stay lower than other types. Most require no grooming over their upper surface, so only need trimming around the edges. Scraps from trimming during winter can become cuttings for bare patches or elsewhere in the garden. Several types root efficiently.

Star Jasmine

Star jasmine blooms with fragrant profusion.

This jasmine is quite a star. However, this star is technically not a jasmine. Star jasmine, Trachelospermum jasminoides, is instead related to mandevilla and oleander. For many years, it has been one of the most popular vines for home gardens as well as large scale landscapes. It works well either as a ground cover, or as a relatively docile climbing vine. 

As ground cover, star jasmine gets about two feet deep. It will be lower and more refined with shearing, but will likely bloom less. It tries to climb shrubbery and trees, so will need exclusionary pruning. However, on a chain link fence, star jasmine works splendidly as a shorn faux hedge. It grows fast to more than ten feet high, but can get significantly higher. 

The richly fragrant bloom is most profuse about now, and can continue sporadically until autumn. The inch wide and bright white flowers are shaped like stars, and hang in small clusters. After bloom, the distinctly glossy and dark green evergreen foliage is handsome alone. Individual leaves are a bit longer than two inches and a bit broader than one inch.