I saw two semi-dwarf oleanders blooming the other day in all their glory. Oleanders appear to be back with a vengeance after several decades of being plagued by a bacterial disease. This is a real boon to those who crave an ever-blooming hedge that never needs to be watered once established.
The disease-causing bacteria — Xylella fastidiosa — is vectored by the glassy-winged sharpshooter, a half-inch long leafhopper insect. This leafhopper appears to have finally been subdued wherever it formerly thrived in California by a parasitic wasp known as Cosmocomoidea. The wasp, which has taken 30 years to make its presence felt after being released by entomologists, lays its eggs inside leafhopper eggs. As the wasp larvae hatch, they consume the eggs. In addition to oleanders, bacteria-vectoring leafhoppers visit grapevines, peach, plum, mulberry, and almond trees as well as shade trees such as sweet gum (Liquidambar), elm, oak, sycamore, magnolia, and jacaranda.
Make sure that if you spray insecticide on any of the fruit or shade trees in question, you avoid the use of products that kill beneficial insects such as parasitic wasps.
In truth, the two semi-dwarf oleanders that I recently ogled — a Petite Pink and a Petite Salmon — have been growing for well over 20 years and have barely shown the leaf scorch symptoms of the taller conventional types; the semi-dwarfs either had a higher tolerance to the infectious bacteria or were just not as tasty to the offending leafhopper. Oleanders are in bloom nearly all the time and seeing them made me think of other non-stop bloomers. All the plants mentioned below are in bloom from spring through frost and some of them flower in winter as well.
Leading the list of constant bloomers is lantana. There are many types, ranging in size from tall bushes to ground covers and the bush types may be kept low through pruning so that they become ground covers as well. Once they cover the earth, whether through a natural prostrate growth habit or through pruning, lantanas never need to be watered. Prostrate varieties are purple or white; there is also a semi-trailing red, a compact lemon, and taller types with yellow and orange stigmas or yellow, salmon, and orange stigmas on the same flower.Mexican cardinal flower (Lobelia laxiflora) is an outrageously boisterous ground cover that spreads quickly due to its rhizomatous growth and quite colorfully due to its pendulous, tubular, flared yellow and orange flowers — a fitting match to the orange and yellow lantana variety mentioned above. Where the soil stays wet, it will cover a giant planter bed in a single season. Where water is less abundant, it will survive just fine with more limited growth. The species name laxiflora means “loose flowering” and refers to the fact that its flowers will appear wherever the plant happens to sprawl.
Cigar or firecracker plant (Cuphea ignea) would complete the yellow-orange, long-blooming triumvirate that includes lantana and Mexican cardinal flower. Cigar plant is covered with hundreds of one-inch long, red-orange tubular flowers tipped in yellow, hence its common name. Cigar plant flowers so heavily that shoots have been known to bend over under the weight of their blooms. Hummingbirds flock to it. You can water it frequently or pretty much forget about it, let its soil go dry, and it will continue to flower profusely. Leaves are dark green and diamond-shaped and it prefers full to partial sun exposure. Propagation is by shoot-tip cuttings and is easily accomplished in fall or spring. Mature height and girth is three to four feet.
Less common than cigar plant, but of equal if not greater garden worthiness is candy corn plant (Cuphea micropetala). Its cylindrical flowers are longer than those of cigar plant — mostly yellow with orange bases — and it is a taller and even more robust and drought-tolerant species than its cousin.
Mexican sage (Salvia leucantha) is a staunch perennial which reaches a height and girth of three to four feet and will persist in the garden for up to a decade. Flowers are wooly purple wands, nicely complemented by gray-green foliage that has a delightfully honeyed fragrance. Give Mexican sage full to partial sun. You can propagate it on-site once temperatures cool. In mid-October, detach four- to six-inch shoot terminals (known as cuttings) just below a node (where leaves meet stem), remove bottom leaves, and then insert these cuttings into the soil. By next spring, they will already have begun to send out roots and new leaf growth will be visible soon after. Even in the hottest weather, Mexican sage should require no more than a single soaking per week. When Mexican sage starts to look shabby, cut it back to a height of eight inches.
Hot lips (Salvia microphylla x jamensis) seems to be always in bloom. Many salvias are drought tolerant but this stalwart hybrid beauty surpasses them all. It will grow best with half to three-quarters of the day’s sun in our interior valleys and, in such exposures, once established, will only require watering once every two weeks, if not less, during the summer. Flowers are visible from late winter until fall, with some decline in bloom during hot, mid-summer weather. Petals are characterized by a doubly curvaceous red segment bordering a complimentary white one.
Society garlic (Tulbaghia violacea) bears mauve flowers in all seasons and sips a bare minimum of water. Periodically, society garlic loses its elegance due to an accumulation of brown flower stems, dried-up leaves, or both. Instead of picking away at these spent appendages, cut the plants down to ground level so that a clump of fresh and vivid new shoots can emerge. Society garlic may easily be propagated by division but some may be deterred from planting it due to its sharp odor, which is more reminiscent of onions than garlic. However, sweet garlic (Tulbaghia simmleri) is also long-blooming, if not as prolifically as society garlic, but its scent, while powerful, is olfactorily pleasing.The championship ever-blooming plant of course is bougainvillea. In truth, its omnipresent color is due to modified leaves known as bracts (each subtended by a golden yellow flower), appendages that are also responsible for the non-stop color we see on crown of thorns (Euphorbia milii).
Perpetual garden color can be achieved with foliage as well as flowers. For instance, Tequila Sunrise may sound like a kaleidoscopic hangover or perhaps what sunrise looks like in the skies about the town of Tequila, in central Mexico, but it’s actually the name of a mirror plant (Coprosma sp.). Indigenous to Australia, New Zealand, and the island of Borneo, mirror plants have foliage that truly shines, as though it had been varnished and polished, if not quite to the extent that you can actually see your reflection looking into its leaves. Many cultivars are available, each with a different combination of foliar colors. Tequila Sunrise leaves are yellow and green when they first emerge, but soon thereafter display an irradiance of burgundy and pink as well.
Although these plants have a reputation for being finicky, they do fine when left alone and will accept minimal water, as in a single weekly soaking. I have seen them grow for years without attention but they definitely prefer morning sun, showing signs of stress when given all-day sun exposure. In the South Pacific, its foliage is used as an antibiotic to prevent wound infections and grind its seeds, much like coffee beans, for brewing into an energy drink.
Tip of the Week: Pink clover or gumdrops (Persicaria capitata or Polygonum capitatum) is drought tolerant, ever-blooming, and blessed with stolons (underground runners), too. These stolons may travel a long distance, with adventitious shoots and then whole plants popping up in unexpected garden nooks and crannies.
Pink clover, which flowers from spring until fall, has been cursed by gardeners more than once for its aggressive tendencies. Yet in times like these, when water is an issue, that aggressiveness could be exploited for ornamental coverage of large areas with a bare minimum of irrigation. Once established, pink clover forms a mat so dense that weeds cannot grow in it and water can barely evaporate from the soil below. Pink gumdrops have dark green leaves with red chevrons. This is a decorative ground cover in every respect. Plant it behind retaining walls and it will cascade down and soften the concrete or stucco facade; plant it in a hanging basket or in a clay pot and it will happily spill over the edges of your container. Pink gumdrops can take sun or light shade and will even grow under trees – such as pine and eucalyptus – that resist association with most plants.
Please send questions, comments, and photos to joshua@perfectplants.com.
