Ground cover: You can’t live with it. You can’t live without it.
Some have described ground covers as “garden thugs” or even worse, since they can brutally bully plants in their vicinity, to the point of suffocating or even strangling them if left to their own devices. However, by choosing shallow-rooted plants that spread quickly and flower abundantly, you may re-evaluate your thoughts on certain select ground covers, at least, and come to see them as friends rather than foes.
One of my favorites is bacopa (Sutera cordata), suitable for both full sun and partial sun locations. It flowers non-stop for several years in white, pink, or blue and stays less than a foot tall. It is also a spiller and will gleefully grow over block walls or out of pots.
Creeping boobialla (Myoporum parvifolium) is one of the toughest ground covers. It blooms most of the year, and the Fine Form variety stays under a foot tall. I have seen it growing near the Dead Sea where average daily summer temperatures exceed 100 degrees. Yet it is also cold tolerant down 18 degrees.
String of pearls Senecio rowleyanus ground cover for containers. (Photo by Joshua Siskin)
Peruvian lilies (Alstroemeria spp.) benefit from weekly watering but can make do with less. They blanket the ground as they spread vegetatively with their rhizomes’ assistance, creating a living mulch that minimizes the evaporation of moisture from the soil surface. And should you suffer a mid-summer breakdown of your irrigation system, there is no need to worry; even if your Peruvian lilies die back down to the ground, their rejuvenation will come in the form of new vertically skyrocketing shoots, ascending from their resilient rhizomes, when watering resumes.
A bonus: As cut flowers, Peruvian lilies reliably last two weeks in vase arrangements, longer than the blooms of any other garden plant. Their typically pink flowers combine well with yellow daylilies and blue lilies of the Nile (Agapanthus spp.), although Alstroemerias in yellow, orange, red, and purple are also available. Tiny thread-like insects known as thrips, which may nibble flower petals, are often a nuisance so make sure you shake them out of the flowers you bring inside for vase arrangements.
I have found fairy crassula (Crassula multicava) to be the ultimate solution for difficult-to-plant areas, especially in half-day sun to shady exposures. This round-leafed crassula grows with a minimum of water in any kind of soil, whether fast-draining or compacted. It will dry out in blistering full-sun exposures with no water — in which case, you will want to soak it occasionally — and will blacken somewhat in a freeze, but otherwise holds its own quite well.
It is called fairy or mosquito crassula because of its delicate pinkish-white flowers that hover over the foliage in winter and early spring. It grows quickly but is neither invasive nor thatch building and is easily propagated. It can thus supply you with an endless source of ground cover where your budget for new plants is limited.
At any time of the year, detach stem pieces with a few accompanying leaves, stick them in empty garden spots, and they will root and begin growing soon enough. This ground cover consistently thrives where nothing else will grow, including under pine trees and eucalyptuses, and where dense tree roots have compacted the earth.
Sedum confusum doesn’t have a common name and is appropriately possessed of uncommon qualities. It doesn’t get woody and doesn’t build thatch. It grows quickly, but is not invasive. It smothers most weeds. Its roots hold the soil well, but it can be uprooted with a gentle tug. It is a succulent plant that heads the lists of both drought-tolerant and fire-resistant species.
Volcanic sorrel (Oxalis vulcanicola) is a wonderful ground cover, a hidden gem that deserves wider recognition. Three varieties are available: Aureus, with green to golden leaves; Molten Lava, with yellow to orange to light burgundy leaves; Zinfandel, my favorite and the most typically seen, with green to burgundy to nearly black leaves.
The more sun you give volcanic sorrel, the darker its foliage, although it is also suitable for half-day sun or bright shade locations. Like most sorrel or Oxalis species, the foliage of volcanic sorrel is shamrock-shaped. Its starry flowers are bright yellow and adorned with thin burgundy lines at the base of each petal.
Volcanic sorrel is well-suited as a ground cover. Each plant grows six-to-ten inches tall and one-foot wide. It makes an excellent companion to the indestructible purple shamrock (Oxalis triangularis), notable for triangular foliage resembling purple butterflies and mauvish white flowers. Propagation is achieved by rooting stem cuttings in water or by division of the rhizomatous roots.
If you are thinking ground cover around indoor plants or container plants outdoors makes no sense, you may want to think again. String of pearls (Senecio rowleyanus) is a succulent that can take regular water or barely any water at all. Its roots are superficial so it will never compete with the roots of your containerized specimens.
California native of the week: Common yarrow (Achillea millefolium) is one of the best starter plants for a California native garden because it is virtually indestructible. You can find it growing wild throughout the state and it can grow in almost any soil type, requiring minimal water. It spreads by seed and by rhizomes. White flowers are magnets to bees, butterflies, and beneficial insects. Its dense, mat-like growth and ability to absorb foot traffic makes it suitable as a lawn replacement. Some herbalists consider yarrow to be the most medicinal plant in the world, with curative properties that extend to every organ of the body. Those who know how to prepare and utilize its infusions, its decoctions, and its teas, swear by yarrow for treatment of headaches, flu, stomach disorders and a host of other ailments. Common yarrow is widely available in nurseries that feature California native plants.
If you grow a noteworthy ground cover more people should know about, please share your experience in an email to email@example.com. Feel free to send questions, comments, or garden problems or inspirations here as well.