Perennials are often planted by themselves in beds or borders. A bed is a cultivated area surrounded by an open expanse, usually a grass lawn. A border is a cultivated area that bounds or borders an expanse, such as the perimeter of a lawn. It often adjoins a walkway.
Beds and borders may be designed in either informal or formal styles. For most of today’s gardeners, a formal bed seems more appropriate in a public park or on municipal grounds than in one’s own backyard. Beds are generally less popular and practical than borders for the simple reason that they look best with fairly large open areas. Putting a bed into an average-sized yard is like placing a very big table in the middle of an average-sized room—it substantially reduces the free space.
Still, beds have a number of important advantages. One strong proponent of informal beds, or island beds, as he calls them, is Alan Bloom, one of the world’s foremost authorities on perennials. Bloom favors beds for three reasons: first, they are accessible from all sides and hence are easier to maintain than standard borders; second, they admit more sunlight and allow better air circulation, which benefits plants; and third, they can be viewed from all sides and so offer more possibilities for the attractive arrangement of plants. If these features appeal to you, and you have the space, beds may be ideal for your garden.
The greatest advantage of borders over beds is that borders allow more open space. In a yard of standard urban or suburban dimensions, leaving the center open creates a more spacious feeling, provides space for recreation, and provides a “quiet” space to contrast with whatever visual activity there is on the perimeter of the yard—trees, shrubs, or the flower border itself.
Much of the effectiveness of a border depends upon the open space it defines. There should be a pleasing relationship between the depth of the border (the distance from front to back) and the width of the yard. For example, if borders are proposed for both sides of a yard that is 40 feet wide, making the borders 12 feet deep would create a tunnel effect. For a more pleasing proportion between a border and the space it encloses, its total depth should never exceed more than a fourth of the total width of the yard. In the example just used, each of the borders should be 5 feet wide, leaving 30 feet open between them. (Here’s the math: one fourth of 40 is 10. Since two borders are needed, 10 divided by 2 equals 5; hence, each border should be 5 feet wide.)
In addition to allowing more open space, borders serve to soften the lines of buildings, fences, walkways, and lawns.
Borders are often installed so that they are flush against a building or fence, which makes them accessible from only one side. This situation limits the border depth to about 5 feet. Having the border any deeper would make it difficult to tend plants in the back without walking on those in front. It is possible, however, to have a deeper border if a path at least 30 inches wide is left behind it on which the gardener can walk to weed, stake, groom, or prune from behind the scenes. The tall plants in the border hide this rear path from view. Leaving such a path also allows more of the air circulation plants need and makes the border less vulnerable to invasion by the roots of shrubs or trees behind the border.
Other design considerations are edging and—for a border—background.
Backgrounds
For backgrounds, most of us must settle for whatever currently separates our property from adjacent properties. This most often is a fence or wall but may also be a hedge, shrubs, or, in part, buildings. The most attractive backdrop for a secluded garden is a stone or brick wall. Next best is a weathered, natural wood fence. If fences are painted or stained, they may need to be redone every few years. It’s best to choose paint or stain closest to the color of the wood in its weathered state. Medium to dark browns or grays generally make the best backgrounds for flowers.
If the fence or adjacent building is unsuitable as an attractive backdrop, create a background by planting vines. Wisteria, trumpet vine, lace vine, honeysuckle, climbing hydrangea, and ivy are just a few possible choices. The green leaves will much improve the appearance of the background, and some vines contribute their flowers to the total effect as well.
Shrubs make a particularly attractive background. If there is room, plant some, perhaps mixing evergreen and deciduous shrubs. Or plant a hedge to both block an unattractive view and provide a good dark background for the border. Needled evergreen hedges such as yew generally grow much more slowly than broadleaf hedge plants such as privet. They take fewer nutrients from the soil and are thus much slower to invade the border. If planted as gallon-sized plants, however, they may take 10 years or more to fill in completely. It may be well worth the savings in time to start with larger plants.
Tall perennials can also serve as a background for the shorter flowers in the border; hollyhocks and delphiniums have long been used for this purpose.
Edgings
An edging sets off a bed or border from whatever is immediately adjacent, for example, a gravel path or lawn. Edgings are useful for discouraging grass or weeds from sneaking uninvited into the border as well as for keeping gravel on the path where it belongs.
They also give the border a clean, neat line. If the bed or border fronts onto a lawn, a row of bricks laid side by side and set slightly lower than the level of the turf not only defines the planting area but makes an excellent mowing strip. Wood 2×4’s or other milled lumber, including railroad ties, make a good straight edging. The grass does have to be trimmed by hand where it meets the wood.
For a less formal look, fieldstone set in mortar is attractive, especially if plants such as basket-of-gold or yellow-archangel are allowed to drape and trail over them. Large stones also make an excellent edging. Another easy way to define the edge of a planting area is to install the small flexible wire fencing commonly available at garden centers.
Where a walkway or lawn flanks the bed or border, many people choose to have the first row of plants grow into the lawn or pathway in a natural manner.
Whatever you choose as your edging, remember that unless there is some kind of underground barrier between flowers and the lawn, there will be some extra weeding. Garden centers usually carry inexpensive rolls of metal or plastic strips for just this purpose.