Pergola – A Place to Dream
A pergola looks impressive and provides a pleasantly shaded spot to sit and eat or walk beneath. There is space for a pergola even in a small garden, and construction is surprisingly simple.
Pergola means ‘leafy walk’ in Italian. This plant-festooned frame is a pleasant and useful addition to any garden.
A pergola entirely covered with plants is sure to become a favourite spot. It provides a living curtain of plants offering protection from wind, sun and prying eyes, while the structure provides an harmonious and attractive link between different areas of the garden.
On hot days, the plants offer welcome shade. As the sun only partly penetrates the foliage, the pergola will be filled with dappled light and shade.
When it comes to choosing plants for your pergola, you can let your imagination run riot. A large variety of plants can be trained along the frame.
You can grow new plants for the pergola every year, sweet peas and nasturtiums work well, forming a wonderful flowering curtains. You could also choose Russian vine, annual hops or Virginia creeper for a fast growing leafy cover. Other climbers that work well over pergolas include clematis, climbing hydrangea, honeysuckle, winter jasmine, wisteria and all sort of climbing roses.
Positioning Your Pergola
A pergola should not normally stand by itself in the garden, but should form a link between different man-made features, or to connect man-made structures and planting.
You can use a pergola to join the terrace to the house, link a sitting-out area to the house, or to divide the flower garden from the vegetable garden. To give as much shade as possible, the pergola should be positioned running from north to south.
A pergola with two or more sets of beams and crossbars (the planks that run across the beams, forming a support for the pergola’s green ‘roof’) creating a covered corridor. This can be large enough to contain places to sit, as well as providing support for climbing plants or vines.
A pergola with only one set of upright beams and a crossbar resembles a door frame or flowering arch.
Wood is the most common material used in pergola construction. You can build a pergola from logs or sawn timber, beams or planks. When planning your pergola, bear in mind the type of plants you want to grow. A vine such as wisteria, for example, can become very heavy as it matures, so you need a sturdy structure built from tough materials to support it.
As the wood will be exposed to wind and wet weather, it must be protected with a stain or paint. Applying several coats of wood preservative protects the timber against dampness and pests.
Take care not to use preservatives such as creosote that are poisonous to plants.
As well as timber, you will need galvanised steel fastenings to join the structure together and, in some cases, for anchoring beams to a wall. Natural stone or concrete is suitable for foundations.
Anchoring the Pergola
The wooden beams should be attached to frost and moisture-resistant foundations. In order to protect the wood from rot, each upright should be placed on a steel bolt or inserted in a steel foot, so that it clears the ground by at least 5cm.
A good method for anchoring the pergola in the ground is to cast the steel posts directly into a concrete base measuring 30cm x 80cm. If you are building the pergola against a wall, attach the upright beams to the wall with a steel bracket.
Stability is Key
Choose timber that suits the style of your house and the size of the pergola. The upright posts and the connecting beams should be 10-16cm thick. A width of 6-10cm is enough for the crossbars.
The joints between the upright posts and the crossbars should be screwed and pegged. As these joints are crucial for the stability of the whole construction, make sure that you secure them very carefully. No rainwater must be allowed to seep into the joints, as this would cause the wood to rot, so ensure that all joints come on the underside.
The height of the pergola – that is, the height from the underside of the beams to the ground – should be at least 2m. This allows people to walk comfortably inside it. The ideal height is 2.5m.
If you are building a corridor-like pergola, place the vertical posts at intervals of approximately 3m. The crossbars should be placed along the beams at intervals of 40-80cm.