Too much water can be as much of a problem as not enough. Too much direct sun exposure can likewise be as much of a problem as not enough sunlight. Scotch moss, Sagina subulata ‘Aurea’, wants regular but not excessive watering, and only a bit of shade without darkness. To propagate, pieces with roots can be torn from healthy plants and ‘plugged’ (planted) as new plants where more are desired in early spring or autumn.
The remarkably finely textured and dense foliage makes a nicely refined ground cover for confined spots, or fills in the spaces between stones in a wall or walkway. It gets only about an inch deep, with tiny and obscured stems that get no longer than four inches. Stems develop roots where they touch the ground to creep any farther. The tiny and narrow leaves do not get much longer than a quarter inch. Tiny white flowers that bloom late in spring may not get noticed. What distinguishes Scotch moss from richly deep green Irish moss is that it is instead yellow or almost chartreuse.
There are not many flowers as blue as those of plumbago, Ceratostigma plumbaginoides. Individual flowers are not much more than half an inch long, but can be quite abundant until autumn. Each of the many terminal flower clusters is on a rather reliable schedule, so that new flowers begin to open as older flowers begin to fade.
Thin stems stand only about half a foot to a foot above underground rhizomes. Individual plants get about 3-feet wide, but realistically, will slowly spread farther if conditions are right. They do not spread fast enough to be invasive, but can get into some unexpected spots if not controlled. The simple leaves are about two inches long.
The main problem with plumbago is that it is deciduous, so it dies back to the ground in autumn. The weather is too mild here to produce the good fall color seen where autumns are cooler. Plumbago is a popular bulb cover because new growth, although slow to develop, emerges just in time to obscure fading foliage of early spring bulbs like daffodil and tulip.
Plumbago also works well with stone, since the stone is still appealing without the foliage through winter. The wiry stems weave nicely through otherwise bare cobbles, or spill slightly over low stone walls. Even though shade inhibits bloom, plumbago makes a nice informal ground cover under open shrubbery.
If the Latin name of dwarf periwinkle is Vinca minor, it is logical that large periwinkle should be Vinca major. Large periwinkle is more commonly known simply as periwinkle or common periwinkle, although it is not as common as dwarf periwinkle is, at least in landscapes. In some regions, it has naturalized as an invasive weed.
Some might accurately say that periwinkle is shabbier than the relatively neat and dense dwarf periwinkle. Others might say that it is just rustic or informal. The wiry stems stand less than a foot tall before they bend over from their own weight. Fallen stems can root where they touch the ground, and grow into new plants over winter.
The evergreen foliage is rich green, and a bit darker than the top of a billiard table. The simple paired leaves are about an inch and a half to two inches long. The slightly purplish blue flowers are about an inch and a half wide, with five petals each. Bloom is sporadic, but almost continuous, except for a lapse through winter.
The small yellow flowers are the giveaway. Real strawberries have white or maybe pink flowers. Otherwise, mock strawberry, Potentilla indica, looks very much like wild strawberry, with similar small red fruits and neatly serrate trifoliate leaves (that are palmately divided into three leaflets). The berries are edible, but do not taste like much.
Like real strawberries, mock strawberry spreads efficiently by stolons. If watered occasionally and sometimes fertilized, it is probably a better groundcover than the common ornamental varieties of wild strawberry. It is invasive in some areas.
Because its common name is so unappealing, dead nettle is more commonly known by its Latin name, Lamium. or more specifically, Lamium maculata. It is a low and subdued plant with pastel pink, lavender or white blooms, and small deep green leaves. However, modern garden varieties have silvery variegated foliage that brightens shady spots. Some are yellowish green.
The herbaceous stems spread only one or two feet at first, but then root into the soil where they land, and continue to spread some more. The mounding growth can get about half a foot deep, or a bit deeper where it can pile up on other plants or rocks. After late spring or early summer bloom, deteriorating flower stems should be shorn back to enhance density of foliar growth below.
Stems that begin to spread a bit too far into areas where they are not wanted can be left long enough to develop roots through spring, and then pulled up and planted where they are wanted. Even before they spread that much, no one would miss a few rooted stems discretely taken from established plants to make copies. Plants in sunnier spots want richer soil and more water.
Now that leaves are falling, they need to be raked. Large leaves, like those of sycamore and fruitless mulberry, can shade out lawn, shallow ground cover or dense shrubbery. If shade is not a problem right away, mildew can be after only a bit of rain. If abundant enough, finely textured silk tree or jacaranda foliage that typically sifts harmlessly through shrubbery and most ground cover, can accumulate and damage lawn, dichondra and the densest of ground cover. Walnut foliage has an herbicidal effect on sensitive annuals and some perennials.
Foliage is only beginning to fall. Cooling weather causes deciduous trees to shed more. Rain and wind bring the foliage down even faster. Even evergreen trees that naturally shed throughout the year will likely shed more through the upcoming wintry weather. Some trees start to defoliate early in autumn. Some hold their foliage until frost. Some trees that seem to be evergreen hold their foliage through winter, and then only drop their older foliage as it gets replaced by new foliage as winter ends.
Pavement and decks should be raked of leaves, not only to avoid staining, but also because rotting leaves can become dangerously slippery. Curbside gutters are too visible to get neglected for too long. However, heavy rain can quickly deliver to the cleanest of gutters a mess of fallen leaves as well as any other debris and litter that happens to be up the road. Strong wind can be filtered through hedges, leaving drifts of blowing leaves.
Leaves should also be cleared from roof gutters and downspouts, and may need to be cleared away again later in the season. More debris may need to be removed from awkward spots where it might accumulate, such as behind chimneys. Flat roofs may need to be raked.
There are a few exceptions to the need to rake fallen leaves. Where they get absorbed into coarse ground cover like Algerian ivy, falling leaves are generally not a problem. Pine needles and cypress foliage can be left if it happens to be useful for the natural suppression of weeds. Mature coast live oaks and valley oaks that are accustomed to a layer of their own fallen leaves over the surface of the soil actually want it to stay. For them, the foliar debris is a mulch that adds organic matter, insulates the soil, and retains moisture.
It is fair to say that garden verbena, Verbena X hybrida, is a reliable warm season annual. It gets planted in spring to spread out and bloom through summer with bright pink, red, purple or almost blue, or softer pastel pink or pale white. It is commonly replaced with cool season annuals by late autumn. However, garden verbena is actually a short term perennial that can survive winter to bloom for a few years.
Perhaps individual plants do not last long enough to be practical as permanent ground cover. Yet, if mulched just so, the thin branches can root where they touch the ground, and then grow into new plants to replace the original plants before they die out. Stems do not spread or cascade much more than a foot from where they are rooted. Nor do they stand more than six inches deep.
There is some debate about the origin of the common name of Confederate jasmine. Some attribute it to its popularity in the former Confederate States of America. Others believe it originated in the Malay Confederacy, much closer to its native range. That is irrelevant here, where we know this popular vine with very fragrant flowers simply as star jasmine, Trachelospermum jasminoides.
One might think that it is too common, but there are reasons for that. The dark green foliage is so delightfully glossy all year. As appealing as it is alone, it is even better as a contrasting backdrop for the small but strikingly white star shaped flowers that bloom in profusion about now, and continue to bloom sporadically for much of the rest of the year. The lavish fragrance is totally awesome!
The twining vines climb luxuriantly to about the height of first floor eaves. They can climb much higher, but higher growth takes a while to get as billowy as lower growth. However, it is more often grown as a shrubby ground cover, only about two feet deep. The simple leaves are two to three inches long, and one to one and a half inches wide. The clustered flowers are about an inch wide.
Vines in the wild are downright exploitative. They do not support their own weight, so instead climb or sprawl over shrubbery and trees. Some are satisfied staying down below the canopy of the hosts who support them, as if aware that a healthy host will support them for a good long time. Many vines climb aggressively to the top and overwhelm their hosts, even if it eventually kills them.
There is nothing civil about the technique of the strangler figs, which incidentally includes two popular houseplants, fiddle-leaf fig (Ficus lyrata) and creeping fig (Ficus pumila). They wrap their hosts in networks of stems and roots that strangle the hosts as both the hosts and the clinging vines grow and expand. As the hosts die and rot, the vines develops into self supporting tree trunks.
That is how fiddle-leaf fig, as it is known as a houseplant, grows as a free standing tree rather than as a creeping vine. It is grown from cuttings from the self supporting adult growth rather than the creeping juvenile growth. Conversely, creeping fig is grown from juvenile vines, which find a support to cling to, and ultimately develop shrubby adult growth when they get to the top of the support.
English and Algerian ivies are not quite as aggressive, since they do not intend to kill their hosts. They are not often intentionally grown as vines, and are almost never planted anymore, but their juvenile growth still works as ground cover in many mature landscapes. One of the main problems with ivy is that it is constantly trying to climb walls and trees so that it can bloom and toss seed.
That is not such a problem on concrete walls, but ruins wooden and painted surfaces, and makes a mess of trees. Boston ivy (which is not really an ivy) lacks a juvenile ‘ground cover’ phase, but if kept off of painted and wooden surfaces, happens to work better on concrete infrastructures. It is important to know how a particular vine will behave before selecting it for a particular application.
Carolina jessamine, mandevilla, lilac vine and star jasmine are a few complaisant vines.
Just like real rosemary, the coast rosemary can either be a low ground cover or a dense shrub. Lower cultivars can get nearly five feet wide without getting much more than a foot high. Shrubby types can get nearly six feet tall without getting much wider. Shrubby types are more popular than ground cover types, and are often pruned so that they do not get too broad.
The tiny leaves of coast rosemary are silvery or grayish green, and can be variegated. Small white or very pale lavender flowers bloom sporadically throughout the year, and can be profuse in spring. Established plants do not need much water, but are probably happiest if watered somewhat regularly through summer. Shade subdues silvery foliar color and inhibits bloom.
Shrubby coast rosemary makes a delightful low hedge. It can be shorn like any other formal hedge, but is best where it has space to develop naturally. If space is limited, but not ‘too’ limited, a coast rosemary hedge can be aggressively shorn once annually at the end of winter, and then allowed to grow wild for the rest of the year.