Perhaps the image of the pergola that springs most readily to mind is that of a vine-entwined structure used in sunny Mediterranean climates to create shade and form a covered transition between buildings. Pergolas have many other practical and visual uses in a small space—they can form a semi-covered room or a plant-covered arbor or be used to strengthen some aspect of a garden’s design.
Pergolas that lead from one space to another can be thought of as dynamic or directional pergolas. In contrast, those that cover a wider area, and define a space rather than lead through it, are static in nature.
Directional pergolas can be free-standing or connected to a building. The free-standing type draws the eye down its length, thereby shortening the foreground perspective. There are situations where this is desirable, for instance where a pergola leads the eye to and frames a view or an entrance, or where it is constructed over a path. However, the ground on either side of directional pergolas tends to become merely the “leftovers” in small spaces.
Directional pergolas attached to the side of a building create a colonnade effect and are useful for covering an entrance or keeping the sun from rooms inside. If, in a hot climate, the pergola’s structure and planting alone do not provide enough shade, a roller blind can be attached to the top and pulled across. Alternatively, split and rattan cane blinds can be used to fill in the gaps between the horizontals, which will also create interesting shadows on the ground. In colder climates, blinds are not usually necessary because the spreading foliage of annual climbers is enough to soften the sun’s effect, while in winter, the stark pergola frame allows the light in.
Static pergolas—those that do not lead in one direction but cover a larger area, such as a terrace, or even the entire garden—are a good way of extending the mood of an interior and creating, visually at least, an additional room outside. By providing a ceiling (in the form of the pergola’s horizontals), it is possible to create the feeling of being in a room outside, thus weakening the barriers between inside and outside and increasing the overall feeling of space.
Such static pergolas are rarely free-standing structures, with uprights at both ends of the horizontals. In a small space, there is certainly not enough room for this. Rather, the horizontals are connected to a wall at one end, and sail outward to meet the verticals that rise from the edge of the total covered space. Or uprights may not be required at all, the horizontals simply bridging the gap between two walls, for instance two boundary walls, or a house wall and a boundary wall.
Pergolas on Roofs
Rooftop gardens are often rather exposed, not only to the wind and the great expanse of sky above but to surrounding buildings, and consequently they are not always very congenial. A pergola constructed on a roof will give the space a sheltered feel and, if covered with tough climbing plants, will protect against sun and wind.
It is important to check the strength of a roof before constructing a pergola, since its weight can be considerable (you may need planning permission too). Metal frames are lighter than wooden ones, and if there are walls on either side of the roof area, metal wires or rope can be used.
Pergolas, whether free-standing or adjoining a building, make wonderful hosts to climbing plants—one of the most attractive aspects of a plant-covered pergola is the quality of dappled light that filters through the foliage. Plant material will soften the overall effect of the structure and help provide shade and privacy, the latter being of great benefit in towns and cities where gardens are so often overlooked. Growing plants vertically is also an excellent way of saving space at ground level. Remember, however, to consider the weight of any envisaged planting in relation to the strength of the pergola, particularly if you wish to train plants along wires or rope. Bear in mind too the density of the plant’s foliage and the length of time it is in leaf, since this will affect the amount of shade provided. Evergreen climbers, for instance, may create too much shade in the winter months when maximum light is needed.
Pergolas for Proportion
In many urban areas, where garden spaces are not in scale with surrounding buildings, a pergola’s horizontals can be used to lower the height of the space and create an esthetically pleasing and proportioned area that is comfortable and inviting. If the style of the pergola suits the architecture around it, it will link the space covered more closely with its surroundings.
One of the most useful facets of any sort of pergola is that its horizontals, or the shadows cast by them, can provide a useful visual framework within which to work when designing and landscaping the rest of the garden. The shapes created by the horizontals can be echoed in similarly proportioned areas of paving, gravel, and planting. This will help create the integrated, consistent look that is so visually satisfactory in a small-space garden.
Choosing a Pergola
It is important that the pergola as a whole should be in keeping with the mood and style of the buildings around it. Materials can be treated in different ways to create very individual looks. A pergola’s horizontals can be made in varying dimensions and from a wide range of materials, depending on how much light you want to have from above and your desired look. The verticals must be made from a material strong enough to support the weight of the horizontals. Visually speaking, however, horizontals should be considerably heavier than uprights.
Wood is the most common material for pergolas. Softwood can be used planed or sawn, depending on whether you want a smooth or textured surface. Hardwood is much more expensive, but it is more durable. Any type of wood can be painted, stained, or just treated with a wood preservative. The ends of the pergola horizontals can be shaped to echo architectural features.
Metal is also suitable for constructing pergolas. It is lighter than wooden logs and does not create such an impression of division. To create a pergola that is lighter still, use tensioned wire or brightly colored chandler’s rope as the horizontals, and suspend them between two walls.