Arborvitae

Arborvitae is mostly tall evergreen shrubbery.

During the Colonial Period of America, American arborvitae, Thuja occidentalis, was one of the first native species to become popular for home gardening. It is native as far south as the Great Smoky Mountains, and as far east as Minnesota. Wild trees can be fifty feet tall, with trunks as wide as three feet. They might grow larger to compete with other trees.

Of course, the oldest cultivated varieties, as well as relatively modern cultivars, are much more compact. Many modern cultivars are hybrids. Some are different species. They are densely evergreen shrubbery that work well as hedging. Their distinctly ruddy or grayish brown bark is barely visible. Their bloom is unimpressive. Foliage is their primary asset.

It is quite an asset. Although arborvitae is conducive to shearing, its billowy foliar texture is too appealing to compromise by frequent shearing. Scale leaves are barely more than an eighth of an inch long, like those of junipers, but are more pliable on soft and flattened foliar sprays. Such sprays are delightful coniferous evergreens for wreaths and garlands.

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Evergreen Tendencies Are No Mistake

Evergreen foliage is resilient through winter.

Evergreen plants retain foliage throughout the year. Deciduous plants defoliate for part of the year. That is the simplest explanation. The various reasons for shedding or retaining foliage are not so simple. Annual plants die after their single growing seasons. They can not live long enough to be either evergreen or deciduous. Some plants just may be both.

Foliar color, to some extent, conforms to preferable environments. Monterey cypress and Monterey pine have richly deep green foliage. It maximizes absorption of sunlight within the foggy coastal regions that the trees inhabit. Blue spruce has glaucous bluish foliage. It reflects a bit of sunlight to protect from sun scald within severe high mountain climates.

Similarly, deciduous plants generally defoliate for environmental situations. Most go bare for winter, in order to be less susceptible to damage from wind and snow. Bare stems do not collect as much heavy snow as foliated growth. They are also less resistant to wintry winds. If foliated, they are more likely to succumb to wind or overburdening snow weight. 

Evergreen plants may retain their foliage because they are from climates in which winter weather is not so harsh. Wind may be no more extreme than it is in other seasons. Snow may never occur. Plants from tropical regions may be unfamiliar with colder weather and shorter daylength associated with winter. Their evergreen foliage might function all year.

Some tropical plants that are evergreen within their native environments may defoliate or die back as a result of even mild frost. Some recover as if deciduous. (Those that can not survive local climate conditions are not very popular here.) For example, canna die back to the ground after frost, but regenerate later. In tropical climates, they can be evergreen.

Evergreen species from mountainous regions or extreme northern latitudes are generally uncommon here. They prefer harsher weather. Although evergreen, they are remarkably resilient to wind and snow in the wild. They are likely evergreen to always stay receptive to limited sunlight whenever it is available, though wintry weather is possible at any time. 

Golden Pfitzer Juniper

Fresh new shoots are most colorful.

Of the several junipers that were too common decades ago, the golden pfitzer juniper, Juniperus X pfitzeriana ‘Area’, was the one outfitted with cheery, bright yellow new foliage each spring. Similar but more compact varieties that are more popular now were rare back then, or simply not yet invented. Contrary to the stigma, golden pfitzer juniper is a very tough shrub, which is why so many from decades ago remain in older gardens, and new plants can sometimes be found in nurseries. Once established, they need very little water, or none at all. A bit of partial shade is tolerable, but inhibits color. Angular branches radiate outward, with the finely textured foliage drooping only slightly at the tips. Mature plants get wider than six feet, and taller than four feet. Crowded plants can stand taller than six feet. Golden pfitzer juniper can technically be shorn as hedges, but are so much more appealing if selectively pruned to maintain their natural form. They are at their best where they have space to spread out naturally without pruning.

Shiny Xylosma

Shiny xylosma has pleasantly glossy foliage.

Where it had been left to develop naturally in old freeway landscapes, shiny xylosma, Xylosma congestum, grew as small trees. The largest are significantly taller than twenty feet. They can be pruned up to expose their nicely flaking bark on sculptural trunks and stems. The evergreen foliage is shiny and rather yellowish green, somewhat like that of camphor tree. The slightly serrate leaves are about two inches long or a bit longer. The tiny and potentially fragrant flowers are rarely seen, and not worth looking for. In refined landscapes, shiny xylosma is popular as a shorn hedge. Xylosma congestum ‘Compacta’ has denser growth, and can be kept only a few feet high if necessary. Vigorous shoots can have nasty thorns hidden in their deceptively gentle foliage. Once established, shiny xylosma does not need much water. It prefers full sun exposure, but will tolerate a bit of shade.

‘San Jose’ Juniper

Do you know the way to San Jose?

Juniper seedlings are initially outfitted with needle-like juvenile foliage. As they mature, most develop scale-like adult foliage. ‘San Jose’ juniper is the juniper that does not want to grow up. Even very old specimens exhibit odd tufts of juvenile foliage. Variegated ‘San Jose’ juniper has random cream colored blotches. The angular but sprawling stems can spread more than six feet wide without getting two feet deep.

Weeping White Spruce

41029As the colorful deciduous trees go bare, the evergreen trees get more attention. A weeping white spruce, Picea glauca ‘Pendula’, really stands out. It grows slowly to only about fifteen feet tall and maybe five feet wide, so does not need as much space as a typical spruce tree. What makes it so distinctive is the weirdly pendulous stems that hang limply from a strictly vertical trunk. It is hard to believe that it is only a different variety of the same species as the dwarf Alberta spruce, which is very short, dense and symmetrically conical, with stout little stems. The foliage of weeping white spruce is lighter green than that of most other spruces, but is not as blue as that of blue spruce. The short and stiff needles are rather prickly to handle.

The narrow and weirdly sculptural form of the weeping white spruce is no good as a shade tree, but is an excellent trophy tree for a prominent spot. Full sun is best. A bit of shade can cause the main trunk to lean toward sunlight. Young trees should only be staked if they need it, since they can become dependent on stakes. The lowest limbs can be allowed to creep over the ground.

Hinoki Cypress

60615In California, it is hard to imagine that hinoki cypress, Chamaecyparis obtusa, gets big enough to be harvested for lumber in Japan. Almost all of the local garden varieties stay quite short. The largest rarely get up to second story eaves. The most compact types that are grown for bonsai, do not get much more than a few inches tall. Most are somewhere in between, to about ten feet tall.

The ruffled sprays of evergreen foliage are surprisingly dense relative to the soft texture and often irregularly loose branch structure. Mature trees often shed branches to reveal sculptural reddish trunks and limbs within, while maintaining the distinct density of their foliar tufts. The minute leaf scales have rounded tips. (Other specie have pointed leaves.) Tiny round cones are rarely seen.

Because of slow growth and irregular form, hinoki cypress is an excellent specimen ‘trophy’ tree, but not so useful as hedging shrubbery. It prefers a bit of shade, and will tolerate considerable shade. However, varieties with yellow new growth are more colorful with good (but not harsh) exposure. It does not take much pruning and grooming to enhance form and expose branch structure.

‘Little Ollie’ Olive

60302Those of us who appreciate olive trees for their fruit production or distinctively gnarly trunks probably would not understand the popularity of the Little Ollie olive, Olea europaea ‘Little Ollie’. Not only is is completely fruitless, but it lacks sculptural trunks and limbs. It is instead a short and and shrubby plant that gets only about three or four feet tall, with very dense grayish green foliage. Only the narrow evergreen leaves are recognizable as those of an olive tree.

Little Ollie olive behaves something like boxwood, and does not grow much faster. It can even be shorn as a hedge or topiary. It is quite resilient to heat and harsh exposure, and once established, it does not need much water. Because it is so compact, and has such resilient roots, it is popularly grown in large urns or planters. The grayish foliage is a nice backdrop for more colorful annuals and flowering perennials.

‘Red Star’ Atlantic Whitecedar

60106Is it red or white? Actually, it is neither. ‘Whitecedar’ is the common name for Chamaecyparis thyoides, which is a formidable coastal conifer from Maine to Mississippi. ‘Red Star’ is a much smaller garden variety. Its finely textured foliage is bluish green when it first emerges in spring, and can turn slightly purplish or bronzed gray if it gets cold enough in winter, but never turns red.

In more humid climates, ‘Red Star’ Atlantic whitecedar can eventually reach second story eaves, and can get half as broad. It rarely gets half as large locally, and can take quite a few years to do so. The slightly aromatic evergreen growth is densely conical, almost like a lumpy dwarf Alberta Spruce with an upwardly rounded underside. It can be a bit more sculptural if partially shaded.

Even without pruning, ‘Red Star’ Atlantic whitecedar is symmetrical enough for formal landscapes. Alternatively, it can add a bit of formality to relaxed landscapes. Although it is slow to provide privacy, it works nicely as an unshorn hedge. If somewhat crowded in a row, it grows taller faster. Shorn hedges lack natural form, but can recover their natural texture between shearing.

Domingo Pine

90102The big name of this little pine takes some explaining. Domingo pine is a cultivator of an interspecific hybrid of two distinct specie, Eastern white pine, Pinus strobus, and Mexican white pine, Pinus ayacahuite. Until a better name in invented, it is known as Pinus strobus X ayacahuite ‘Domingo’. It is typically but incorrectly abbreviated as Pinus ‘Domingo’, or Pinus strobus ‘Domingo’.

Like many hybrids, Domingo pine got the best of both parents, and also stays compact enough for suburban gardens. Although not quite as soft and blue as Eastern white pine, its finely textured and dense pine needle foliage has a grayish sheen to it. Like the Mexican white pine, it does not need much water once established. It wants full sun exposure but is otherwise not demanding.

Young trees may seem to grow quickly, but growth slows significantly with maturity so that trees to not get much taller than second story eaves. Their typically conical form does not get much more than half as wide as tall. They look best where they have room to stay well branched from top to bottom. Because they are not very big, clearance pruning of lower limbs comprises their symmetry.