By Adrian Higgins
Thursday, November 26, 2009
After being mesmerized by the slow and pretty leaf drop of autumn, we wake up around Thanksgiving day to the reality of the naked garden. The cherry tree that screened the back alley or the trash cans is now an armature of branches and twigs and will stay that way until the buds pop in early April. The winter landscape is open and presents views we'd rather not have.
The urge, often followed, is to stick in evergreens, though it is worth noting that you pay a price for the excessive use of evergreens. Individual plants can have a morose and dark density to them, and collectively they can form a garden that is unchanging and thus dulled.
Another problem is scale. The world is full of yards with ill-chosen evergreens that have crowded out their spaces. This is because their owners were impatient, seeking immediate screening, and so chose plants that are big-boned and fast-growing. The Leyland cypress, which can look handsome if not magnificent in a park setting, has become, famously, the Godzilla of gardening. Five together work as an effective hedge for three or four years, and then, growing at three feet a year, they become tyrannical in their reach.
Before the advent of the Leyland cypress, people used the eastern white pine as the screening conifer of choice. The plants would go in looking like fluffy Christmas trees but, amazingly, didn't stay like that. They would grow tall and shed their lower branches in the process, ruining the screening effect. The first settlers to America found ancient white pines in vast old-growth forests that were 150 feet tall, but with the lower 80 feet of trunk branchless. That image is not in the eye of the hasty homeowner.
If you do have room for a big tree, a place where it will be allowed an unencumbered spread of 20 feet, my advice is to forgo Leyland cypress, white pine, blue spruce and Norway spruce, and go for a Japanese cedar (Cryptomeria japonica), which, when happy, will grow to 30 feet tall in 15 years, forming a pyramidal conifer with lovely finely textured foliage. Yoshino is a variety that keeps its green coloration in winter. The more enriched the soil, the less it will suffer from spider mites, which is the rule for a lot of conifers.
Alternatively, I would plant the underused Himalayan pine (Pinus wallichiana). The needles are long and soft, gray-green in color and arrayed in hanging plumes. The tree has a lot of presence. Both the pine and the cedar keep their lower branches, avoiding the problem with the white pine.
If you need an evergreen in a smaller space, say 10 feet across, you have many choices beyond the common arborvitae or American holly. I have long advised people to plant either the Serbian or Oriental spruce. They are both slow-growing and finely textured, making them perfect for tighter spots. The Serbian spruce (Picea omorika) has needles that are dark green above but blue-white beneath, giving an interesting two-toned effect. The Oriental spruce (Picea orientalis), has short, stubby, dark green needles, giving the tree an uncommonly fine texture.
The incense cedar is another conifer deserving more use. Quite columnar, it fits into tight spaces but grows tall. Like the Yoshino cedar, it holds its green hue in winter. Its botanic name is Calocedrus decurrens.
If you want a native conifer, look for improved varieties of the eastern red cedar. Among the more pleasingly pyramidal varieties are Burkii, Princeton Sentry and Emerald Sentinel.
The Chindo viburnum grows rapidly and tall, without needing too much bed space. I have one I planted about 12 years ago that is now 20 feet tall and eight feet wide. It stands out for its lustrous and smooth green leaves, and is a popular evergreen in Southern states. It is hardy in the District but probably needs a sheltered spot away from prevailing westerly winds.
The Burford holly makes an effective screen, growing to 15 feet in as many years. Unlike many hollies, it sets berries without the need for a male plant. I find the leaves to be so waxy, however, that there is a plastic quality to the plant.
Not all screening plants need to be evergreens. If you buy into the notion that the garden is off-limits in winter (I don't; mild winter days provide some of the best times for tackling projects), you might accept that there is less need for privacy and go for deciduous plants. Although it is used a lot, I'm a big fan of the upright European hornbeam, which is now turning a golden color in advance of leaf drop. With age, it will get to 20 feet and maybe 10 across, but it takes pruning well and can be turned into a hedge proper. The winter tracery of its gray trunk and branches is attractive and the outline perfectly symmetric, always a selling point.