As the last leaves fall, we see all kinds of things that are only visible from our properties in winter. Some are pleasant, but others are eyesores. So it's no surprise that this is the time of year I receive the most queries about evergreen screens.
Other than fences, hedges are the most common solution for creating privacy in residential landscape design. Hedges are shrubs planted in a row so that they'll grow together and form a dense barrier to act as a screening element. Evergreen shrubs offer year-round enclosure.
Shrubs sheared into tightly clipped geometric shapes become an architectural element. But why install plants just to create an architectural barrier? With patience, if you site evergreens properly, they will become ornamental, low-maintenance year-round screens that need not look like walls or fences.
After finding an evergreen you like, verify at the garden center its mature size and growth habit. Even hedge plants must be installed far enough apart to get fairly mature before growing together. Plant them so a screen will form in four to seven years. Then they will develop into an aesthetically pleasing form that will be effective and easy to maintain. Don't try to achieve complete enclosure in one growing season.
For example, leyland cypress, not an exciting plant because it offers no flower or berry, is the fastest growing, most popular evergreen screening shrub in this region. When installed on four-foot centers, the foliage of one plant is touching the leaves of the next in two years. That should not be the goal--plant them six to eight feet apart to allow each a chance to grow full before becoming a visual barrier. They will stay healthier this way, and offer the longest period of screening and ornamental value.
Here are some other types of plants to consider:
* Narrow-leaf evergreens. In addition to leyland cypresses, other narrow-leaf evergreen shrubs for hedges are yews, junipers, falsecypresses (Chamaecyparis species) and arborvitaes. Most do not offer seasonal interest and are not very showy, but all will take some shearing and grow into tight barriers. If they are planted at the proper distance from one another, they might not need much pruning.
* Conifers. Most evergreen, needle-bearing trees are conifers. Common ones are firs, pines and spruces. They usually grow tall with a pyramidal, Christmas tree shape branched full to the ground. To mature to maximum size, they must be planted in full sun. I will often design spruces and firs in groupings to screen the winter wind and enhance privacy.
Spruce and fir trees naturally occur in areas of severe climate conditions and seem to prefer wind and low temperatures to warm, still air. Design them as a screen in areas of good air circulation. Several spruces that I recommend are Oriental (Picea orientalis), Norway, Colorado blue and Serbian. Two of the most adaptable fir trees in this region are white (Abies concolor) and Nordmann.
Swiss stone pines (Pinus cembra) are slow-growing trees with tight blue-green bundles of needles, valuable in the landscape for accent evergreens. They fit into beds with other plantings because they grow slowly; after many years, they will be only 10 to 15 feet wide and 30 to 40 feet high. This pine will not only screen the view, but it also will stand as a handsome specimen planting.
One exception to the pyramidal habit of most conifers is Japanese black pine, which has a handsome sweeping, windblown look. Design these windswept specimens in a Japanese-style garden or en masse as a windbreak. They are a dependable conifer and are tolerant of salt air, so they will also perform well planted near the ocean.
* Broadleaf evergreen shrubs and trees. I find broadleaf evergreen trees and shrubs more interesting because they have flowers and berries or other showy fruits. Some of these shrubs make excellent hedges.
Shrubs that will mass together as dependable broadleaf evergreen hedges are Nellie R. Stevens hollies, common boxwoods (Buxus sempervirens) and species cherrylaurels. Osmanthus will also create a formidable barrier visually and for security, as well as fragrance when it is in flower. But you must give each plant room to develop.
A less formal way to screen without need for a hedge is to place large evergreens in groupings of three to five of the same species together. Or stagger them in a random pattern, such as three or four broadleaf evergreens or conifers strategically placed to screen the necessary areas and yet appear to be located in a hit-or-miss fashion. I call it a "planned randomness" method of planting. Evergreens, especially conifers, can create a park-like setting when planted in this fashion.
If a tall evergreen screen is needed in shade, you have a limited palette. Try American or Nellie R. Stevens hollies, native rhododendrons (Rhododendron maximum), Japanese pieris and leatherleaf viburnums. If you want to achieve tight screening in heavy shade, place plants on the edge, where they will get some sun. Even though they are shade tolerant, they will grow fuller with filtered sunlight.
Several broadleaf evergreens that grow here get large enough to qualify more as trees than hedging plants. These can be installed in random strategic locations. English, American and Foster's hollies are valuable broadleafed evergreen trees to install in groupings or individually as large screens with deep green foliage, berries and handsome pyramidal forms. One of these plants can make a great accent for a planting bed and double as a screen. Several of them will grow into a handsome grouping.
Proper spacing is crucial to the health of the plants. They're living, growing entities. Plant larger evergreen trees at least 10 to 15 feet apart, more for southern magnolias.
Lerner is president of Environmental Design in Capitol View Park, Md. His e-mail address is firstname.lastname@example.org