Where winters are very mild, common lantana, Lantana camara, might bloom through all but the coolest of weather. It generally takes more of a break though. It could finish bloom at any time now, and resume at the end of winter. Where winter weather is cooler, foliage and perhaps stems may succumb to light frost. Growth should regenerate through spring.
The tiny tubular flowers bloom inwardly from the margins of round umbels that are about and inch and a half wide. Flowers typically bloom yellow, and then fade to orange, red or pink. Therefore, the umbels have yellow centers with orange, red or pink margins during the middle of bloom. One cultivar blooms with one hue of yellow. Another fades to white.
Modern cultivars mostly stay rather low and compact. Some sprawl. Older cultivars might get as tall as six feet after a few years. However, after frost damage or coppicing, mature plants may regenerate from their roots, with vigorous stems that get six feet long through summer. The faintly raspy foliage appears to be smooth, and is aromatic when disturbed.
This humongous six inch wide tropical hibiscus, Hibiscus rosa-sinensis, looks like it might be from Hawaii or Florida, but was actually found in K and K Nursery and Landscape of Norman, just south of Oklahoma City, where winter nights are already seriously cold by our coastal California standards. It is happy to bloom so impressively only because it is in a greenhouse. Even here in our pleasantly mild climates, tropical hibiscus are happiest where sheltered above from frost, by eaves or evergreen shade trees that are high enough to also allow warming sunlight through. In the cooler spots, even sheltered plants occasionally get damaged by frost, and need some time to regenerate after winter.
Some of the classic tropical hibiscus that typically have smaller flowers can grow above single story eaves if not pruned down. Most modern varieties with larger or ruffly double flowers rarely reach the eaves, and many stay less than six feet tall even without pruning. The evergreen foliage has an appealing glossy sheen, which is an ideal backdrop for the red, pink, white, yellow or orange flowers.
Prior to the appearance of oleander scorch disease in the early 1990s, oleander, Nerium oleander, was almost too popular, and for good reason. It is remarkably resilient to harsh conditions. It had been one of the more common plants within freeway landscapes since freeways were invented. Now, new plants are rarely available. Only older plants remain.
White, pink or red bloom is most abundant through warm summer weather, with sporadic bloom continuing through most of the year. Some dwarf cultivars bloom with peachy pink double flowers. Plants with enough room to grow wild without much pruning bloom best. Frequent shearing deprives the healthiest oleander of its blooming stems prior to bloom.
The biggest oleander get as tall as fifteen feet, so can be pruned up as small trees, either on single trunks or multiple trunks. However, because their limber trunks can not support much weight, occasional pruning is necessary while trunks develop. Such pruning limits bloom, so should happen mostly at the end of winter. Straight single trunks need staking. Oleander wants warm and sunny exposure, but is quite undemanding.
Stylish modern cultivars have been restoring the popularity of formerly common weigela, Weigela florida. Traditional sorts can reach first floor eaves, with delightfully open branch structure and rosy pink spring bloom. The foliage of most is variegated with white. Newer cultivars are more compact, with more variety of form, as well as of foliar and floral color.
Bloom can be pink, red, rosy red, white, white with yellow centers, or the the familiar rosy pink. Foliage can be green, bronze, deep purply bronze, or variegated with white or pale yellow. As it develops in spring, variegated foliage might be blushed with pink. Shrubbier modern cultivars may get no taller than five feet. Some are lower and densely mounding.
Although deciduous, weigela are popular as short informal hedges. Formal or excessive shearing compromises both bloom and form. After primary spring bloom, several modern cultivars bloom sporadically later in summer. Weigela enjoys a bit of winter chill, so may not appreciate the mildest coastal climates. Partial shade is tolerable, but inhibits bloom.
As long as freeways have been getting landscaped, oleanders have been contributing their profuse white, pink and red bloom. Heat, exposure and lack of moisture do not seem to bother them. They have become less common recently only because of new diseases that had never before been problematic. The diseases do not necessarily kill all oleanders everywhere, but are serious problems where the nurseries that grow most oleander are located.
The largest oleanders can get more than fifteen feet tall, and can be pruned up as small trees with multiple trunks. Oleander trees with single trunks almost never stand up straight, and do not want to give up their stakes. Because flower clusters develop at the ends of new growth, frequent exterior pruning or shearing inhibits bloom. Dwarf cultivars that are naturally proportionate to their space will bloom better than larger types that need to be pruned for confinement.
Oleander flowers are about an inch or two wide, with five petals, although some have ruffly ‘double’ flowers. Unfortunately, double flowers tend to hang on as they deteriorate after bloom. Some oleanders are slightly fragrant. The name ‘oleander’ is derived from the similarity of their leaves to those of olive trees (‘Olea‘), although oleander leaves can get three times as long.
Spring seems to develop suddenly, and without a very precise schedule. Star magnolia, Magnolia stellata, which can bloom as late as early in April, is already finished blooming in most regions. It should be no surprise. Technically, it can bloom before March. Foliage does not compete with bloom on otherwise bare stems. It appears as bloom deteriorates.
The bright white flowers are about three inches wide, and lavishly profuse. Cultivars with pale pink bloom are increasingly popular. Their pink color may be variable, according to the weather. Flowers have more than a dozen narrow tepals. Some are fluffier with twice as many. Fragrance is mild. Stems can be cut and brought inside just as buds pop open.
Star magnolia is more of a deciduous flowering shrub than a small tree. It should not get much taller than six feet, although it can eventually get to be nearly twice as wide. Partly shaded specimens can reach ground floor eaves. The lime green leaves darken through summer, turn pale yellow for autumn, and finally defoliate to reveal sculptural gray stems.
The thin stems of Western redbud, Cercis occidentalis, that had been bare through winter are now outfitted with an abundance of tiny but almost offensively bright magenta flowers. Rounded or nearly heart shaped leaves will become more prominent as bloom fades. As foliage yellows and falls later in autumn, coffee colored pods that are about two inches long remain until they get dislodged by winter weather. Pods can be very abundant on older or distressed plants, or scarce on young or vigorous plants.
Western redbud is typically grown as a large shrub or a small tree with multiple trunks. Mature trees may stay less than ten feet tall, and do not often get taller than fifteen feet, although they can get more than twice as tall where they need to compete with other trees. Once established, western redbud does not need to be watered, but seems to be happiest if occasionally watered through summer. Seedlings that appear around mature plants should be moved or potted while dormant through winter, and while young, since they will not want to be disturbed once they have dispersed roots.
After centuries of breeding, there are more than two thousand cultivars of Camellia japonica! Additionally, there are more than a thousand cultivars of both Camellia sasanqua, with smaller but more profuse flowers, and comparably rare Camellia reticulata, with fewer but garishly big flowers. This does not even include the more than a hundred other specie of camellia found in the wild throughout East Asia.
It is obviously difficult to generalize about so many different personalities. Actually though, the glossy and slightly serrate leaves of almost all Camellia japonica are surprisingly similar. Also, most grow into rounded shrubs that are happy to stay below first floor eaves. Only a few grow into small trees, and only after many years. All prefer rich soil and regular watering.
The flowers that bloom late in winter are the most distinguishing characteristics of the many cultivars. The largest can get more than four inches wide. Flower form is remarkably variable (and can be described as single, semi-double, double, formal double, paeony, anemone or rose). Many have prominent yellow stamens. Color ranges from pure white to red, with every shade of pink in between. Picoteed, striped and blotched flowers are not uncommon.
With indiscriminate pruning, glossy abelia, Abelia X grandiflora, will never develop its natural form, with elegantly long and thin stems that arch gracefully outward. Sadly, almost all get shorn into tight shrubbery or hedges that rarely bloom. If only old stems get selectively pruned out as they get replaced by fresh new stems, mature shrubs can get eight feet tall and twelve feet wide.
Against their bronzy green foliage, the tiny pale pink flowers that bloom all summer have a rustic appeal. In abundance, they can be slightly fragrant. The tiny leaves are not much more than an inch long. Vigorous young canes that shoot nearly straight out from the roots slowly bend from the weight of their bloom and foliage as they mature.
Partial shade is not a problem for glossy abelia, but will inhibit bloom somewhat. Young plants want to be watered regularly. Old plants are not nearly so demanding, and can survive with notably less water. If alternating canes is too much work to restore old and neglected plants, all stems can be cut back to the ground at the end of winter. New growth develops quickly.
As its compact cultivars gained popularity over the years, the formerly common lemon bottlebrush, Callistemon citrinus, became passe. Most are mature specimens in old fashioned landscapes. It is unfortunate. Only lemon bottlebrush and weeping bottlebrush can grow as small trees. (However, lemon bottlebrush is now classified as Melaleuca citrina. Most Melaleuca get notably larger.)
If competing for sunlight, mature specimens of lemon bottlebrush can almost reach upstairs eaves. Well exposed specimens may not get much more than half as tall, with mounding form of about equal width. Removal of low growth to expose sculptural trunks and handsomely shaggy bark promotes higher growth above. Shearing of hedges should not be too frequent to allow some bloom.
Bright red bloom is sporadic through the year, and gets more abundant as summer becomes autumn. The small and staminate flowers are densely set in cylindrical ‘bottlebrush’ formation. These blooms are about two or three inches long, almost as wide, and popular with hummingbirds. Dense evergreen foliage is aromatic. Individual leaves are narrow and about two or three inches long.