By Joel Lerner
Saturday, October 6, 2007
Landscape design is a three-dimensional discipline. You control the depth, breadth and ceiling of your space, and it can run as far as you allow the eye to travel.
Adding a path can expand your view, taking you through a hedge and under an arbor, then disappearing around a curve, giving the illusion that you might follow it for some distance. These sorts of effects are created by considering all levels of the garden, and the ground, vertical and overhead planes are equally important.
GroundThis is where elements such as paving, lawns, low ground covers, perennials and annuals meet the soil. It's the foundation of the garden, and it dictates pedestrian and vehicular circulation. Paths and paved surfaces direct us to a destination.
Stability underfoot requires soil low in organic matter and high in mineral content with good weight-bearing ability.
Build structures on soil that has been undisturbed for several years so there is no chance of settling when you lay a walk or wall.
Nearly all plants begin on the ground plane. Most flora require loose, moist, well-drained soil high in organic material. Walking, hiking or riding over an area just once can affect what will grow there by compacting the soil.
Pollution from cars and industry, insects, disease, neglect, and droughts also affect plants on this plane, but plants can better deal with environmental extremes if their medium is properly prepared.
Lay three inches of compost over the soil surface, then till or spade it 10 to 12 inches into the soil. If your own compost isn't ready yet, buy some at the garden center under the name Leafgro or look for the availability of composted leaves through your jurisdiction.
The only way to know if you need fertilizer or lime to change the soil's acidity or alkalinity is by testing. Check with your local extension service. Some garden centers also offer soil testing and meters to check pH. All plants have different requirements. The "LaMotte Soil Handbook," available from the LaMotte Co. ( http://www.lamotte.com), lists the soil testing and pH needs of a variety of plants.
One crucial element on the ground plane is natural carpeting. Bare areas under plants can develop runoff problems, and steep banks can erode. Acres of lawns are planted for this purpose, but turf grass is not practical under shrubs or on steep slopes, so other types of cover should be used.
Beautiful, plush carpets are available that discourage weeds and control erosion. They come in green, gray-green, blue-green and red, with variegations of gold, white, cream, red and pink.
Here are a few possibilities for carpeting your garden: wild ginger ( Asarum canadense), creeping juniper ( Juniperus horizontalis), creeping phlox ( P. subulata), Japanese spurge ( Pachysandra terminalis), Allegheny spurge ( Pachysandra procumbens), wild stonecrop ( Sedum ternatum), periwinkle ( Vinca minor) and St. John's wort ( Hypericum calycinum). All are native ground covers except periwinkle and Japanese spurge.
VerticalSubdividing areas with vertical elements can make a space appear larger, and the vertical plane can be designed with a rustic or formal ambiance.
Screening to block unpleasant views, provide privacy or establish a barrier from a neighbor's property has been among the top requests from my clients over the years. It's human nature to feel secure and comfortable in a private enclosure.
All shrubs, grasses, vines and trees that grow in the range of eight to 40 feet in height are vertical elements and therefore potential screens. Trellises, a fence section or two, or a couple of conifers are among other candidates.
I am not an advocate of surrounding yourself with walls, fences and plantings, but you should create a private space where you can be alone.
Perhaps a section of fence would be enough, or several large conifers strategically located to block views, rather than a formal hedge.
Groupings of trees and shrubs work well together. Use plants with upright, spreading branching habits. Create a physical barrier by planting several shrubs, a small flowering tree and then some evergreens. Design for interesting flowers, foliage and bark.
One arrangement on the vertical plane could be a hedge of fragrant osmanthus or Alleghany viburnum. Another option could be American hollies and Southern magnolias strategically located to screen selected views, though plants of that scale generally relate more to the top level of the landscape.
OverheadThe overhead plane keeps the landscape to "people-size" proportion. Tree canopies are the best way to do this.
Full canopies on maturing shade trees, such as oaks, red maples, beeches and hickories, should stand above the property, with their lower limbs elevated to permit passage underneath.
Instead of choosing only trees that you already know, think about the features you want, such as flowers, fall color, attracting birds and interesting growth habits. Then go to the garden center and request trees that meet these criteria.
With the exception of one or two evergreens that don't fit small properties, such as dawn redwood and Leyland cypress, most large trees are slow to establish but add the greatest value. The most desirable large shade trees are 30 to 35 feet tall, about half their maximum height. They are too big for you to plant and large enough to offer shade; you can watch them grow for many years.
Old trees are wonderful, if they're healthy. Existing large trees around a new home should be carefully scrutinized for signs of bulldozer, trenching and other construction activities at their roots, especially if the trees are a reason you're buying. It takes three to six years for construction damage to kill a mature shade tree, and taking down mature trees can be quite costly.
Trees are awe-inspiring, but they aren't the only canopies that offer cooling shade. A pergola, portico, belvedere, gazebo, a contemporary canvas shelter or an awning will also offer overhead enclosure. If you want the sky to be the limit, build a pergola or shade trellis to see through to the stars, or an awning that will open to the sky at the push of a button.
The roof height of the structure or lowest branches of a tree will have the greatest impact in determining whether an area feels large or small.
Tall trees, such as white oaks and tulip poplars, offer a monumental scale to the garden as they age. Their lower branches can be as much as 20 feet above the ground. Other shade trees with lower canopies will bring the surroundings into smaller proportion. Trees with lower branching habits include river birch, large crape myrtle, paperbark maple, red maple, saucer magnolia, sweet gum and black gum.
Joel M. Lerner is president of Environmental Design in Capitol View Park, Md. E-mail or contact him through his Web site,http://www.gardenlerner.com.
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