Ipomoea batatas ‘Blackie’

Of ground cover it could easily be said that “You can’t live with it; you can’t live without it.”
There was a time when lawns were the ultimate ground cover, yet over the last decade water conservation measures and overall maintenance costs have whittled away at expanses of green turf.
Today, when ground cover is mentioned, you may think of invasive ivy or something less invasive that grows in fits and starts and, ultimately, is unreliable in providing a permanent, low-maintenance alternative to bare dirt.
A somewhat radical approach may be worthy of consideration here: Instead of obsessing about ground cover, consider planting large swaths of easily maintained floribunda roses or daylilies as lawn alternatives.
These pest-free plants provide cut flowers for vases and bouquets in every season and require less than half the water of a lawn.
If you must plant ground cover, however, I have found fairy crassula (Crassula multicava) to be the ultimate solution for difficult-to-plant areas in Valley gardens, especially in half-day sun to shady exposures.
This round-leafed succulent receives high praise for several reasons.
Fairy crassula grows with a minimum of water in any kind of soil, whether fast draining or compacted. In the Valley, it will dry out in blistering full-sun exposures (south of Mulholland Drive, it grows in full sun, too) 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 (like iceplant) and it is easily propagated, representing a permanent 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 watch them spread. This ground cover consistently thrives where nothing else will grow, including under pines and eucalyptuses, and where dense tree roots have compacted the earth.
Speaking of growing under pines and eucalyptuses, no plant better suits this contingency than Australian rosemary (Westringia fruticosa), an evergreen shrub with grayish-green foliage.
The beauty of planting shrubs, as opposed to ground covers, under trees is their proportionality. They provide an understory that may reach 6 feet or taller, as opposed to prostrate ground cover.
In between the shrubs, lay down a carpet of woody mulch. Here, a relationship with a tree trimmer can be handy since a load of wood chips, deposited on your driveway at no charge, will provide a wonderful, aromatic filler of garden bare spots.
Make sure you keep the mulch away from tree trunks, since fungus will grow where mulch and bark make contact.
Cooler and shorter autumn days make propagation of a host of plants easily accomplished.
At this time of year, you can propagate directly into a planter bed. The biggest obstacle to propagation by shoot tip cuttings is leaf desiccation prior to roots taking hold. But in cooler weather, with leaf dehydration of drought-tolerant or semi-succulent plants a nonissue, you can propagate most sages (Salvia species), perennial herbs (mints, rosemary, thyme, oregano and marjoram), geraniums, nearly all ground covers and many shrubs.
Cut 4- to 6-inch shoot end pieces of leafy plants just beneath a node, where leaf meets stem. Remove the bottom few leaves, exposing the minimum amount of stem needed to stand the cuttings upright. As long as your garden soil drains well, your cuttings should root without difficulty.
You can also propagate woodier plants of all kinds, from roses to hibiscuses, as long as they are given some protection from the elements by means of a coldframe or cloche, which is a bell jar made of glass or plastic.
Keep in mind that nursery production of all woody perennials and ground covers is done from cuttings and there is no reason why you cannot do the same.
Tougher stems such as those of juniper may require a root hormone dip to sprout roots. A tried-and-true technique for propagation, known as layering, is also popular.
Layering involves bending a long shoot of a plant so that it touches the ground. Before burying the bend of the shoot a few inches below the soil surface, make a shallow cut or two in the stem and dust it with root hormone powder, available at most nurseries. Roots will grow from where you nicked the stem.
Next spring, tug gently on the shoot and, once you feel that roots have formed, sever the shoot from the mother plant, dig it up and place in a container or elsewhere in the garden.
Ornamental sweet potato vine (Ipomoea batatas) is a billowing ground cover that grows quickly in the fall in partial sun locations. You can select from ‘Blackie’ or ‘Sweet Caroline,’ cultivars with dark purple foliage and pale violet blooms; ‘Marguerite’ or ‘Terrace Lime,’ lime green to golden cultivars, depending on how much light they receive; and ‘Tri-color,’ with white, pink and green variegation.
Sweet potato vines need fast-draining soil and, for this reason, excel as container specimens. To grow them in the garden, you will have to give them perfect drainage to a depth of 1 foot, which means adding a lot of organic matter and mixing it far down into the soil.
The lime green and dark purple varieties create an arresting contrast when planted together. In tropical climates, these plants yield actual sweet potatoes in addition to their ornamental foliage.
Polka dot plant (Hypoestes phyllostachya) is another fall-loving ground cover for partial sun. You can find varieties with white, pink and red polka dots.
Like fuchsias, polka dot plants prefer a bright exposure but cannot endure hot sun. They get leggy with age, so don’t be afraid to cut them back hard. Polka dot plants are easily propagated from shoot tip cuttings.
Polka dot plant and sweet potato vine are both excellent container subjects, the latter also suited to hanging baskets due to its trailing growth habit.
Mondo grass (Ophiopogon japonicus) is an outstanding ground cover for partial shade. It can be mowed down to the ground every six months and will tolerate light foot traffic.
Tip of the week
If you celebrated the festival of Sukkot, and are still admiring your ceremonial etrog or citron fruit, reluctant to discard it, you may wish to grow your own citron (Citrus medica) tree from its seeds.
To germinate the seeds of a citron or any other type of citrus, soak them in a small cup of water for a week, changing the water daily. Plant the seeds in any well-drained potting soil or make it yourself from equal parts peat moss and sand.
Planted no more than 1/2-inch deep, seeds should germinate in seven to 14 days. You may see more than one seedling emerge from a single seed since citrus seeds are often polyembryonic, a phenomenon also encountered in mango seeds.
As the plants move beyond the young seedling stage and reach a foot or so in size, water them as you would any sun-loving indoor plants, waiting for the soil to go dry between thorough soakings.
Fertilize during the growing season with a 10-10-10 formula but, as winter approaches, cease fertilizing and keep watering to a minimum.
It can take up to five years or longer for a citron tree to begin to flower and bear fruit. Grow it in a container on a sun-splashed patio or balcony or plant it in the ground in a frost-free location.