The vertical height of the garden pergola should be about 2.7 meters (9 feet) above the ground so that the climber can climb a certain amount without obstructing the passageway.
The width across the path between the uprights should be approx the same as the height to achieve a degree of balance. The spacing between the parallel columns can vary from 0.9 to 3.7 meters (3 to 12 feet).
Vertical support columns may need to be set in the soil 45 to 60cm(18 inches to 2 feet). Treat their bases with a wood preservative and extend their life span further by placing 5–7cm (2–3in) of course gravel at the base of the hole, then set the post inside a large drainpipe with the rim just above soil level, filling around with gravel and capping with cement.
Pergolas need to be of quite solid construction as they may be required to support a considerable weight of foliage, and when in open situations, withstand considerable wind buffeting. Therefore, pillars should be at least 5 x5cm (2 x2in) and ideally 8 x8cm (3 1/2 by 3 1/2). The scale of the latter will support a gap of about 60 cm (2 feet) between the girders 15 x5cm (6 x2in) and the lateral roots of x2 1/2 cm (2 x1in).
With larger pergolas, a common practice is to plant two climbers near the base of each pillar, for example, a strong-growing climbing rose with a less vigorous clematis or honeysuckle, the rose to provide additional support for the other climber. Robust climbing plants, such as Montana clematis or wisteria, will cover the beams sooner or later and may require some restraint.
When planting, tilt the climber toward the support and, if necessary, use small canes to build a pergola Bridges. Secure vertical wires or wire mesh up the pillar and tie in shoots to these as they grow. To cover the canopy quickly, train the shoots straight up the posts. Or wrap twigs around a post in order to bloom. Continue to tie the new branches to the beams and sides until the pergola is completely covered. Trim long branches with long-handled scissors.
Think of the pergola as a path. Completely ignoring the fact that its columns and roof are like beams. Just feel the path. Now ask yourself, would you set a path for the pergola you are planning? Does it look right? Or you wonder why I have a path there! What makes sense visually is crucial. The pergola is actually a very fancy walkway, so it needs to be walked back and forth to make sense.
Use high-quality materials. A wood-plastic composite type of column, with good corrosion resistance, A similar appearance to pure wood, with a rural taste. Not only does this look good, but it also saves you time and maintenance costs.
Keep your direction. Facing north is good because it gives shade in summer and lets in warm sunlight in winter.
Trim the details. If you have a modern space, don’t do too much detail on the wood or rotating corner brackets. Keep it square, or add a simple Angle cut.
The bottom of the column may be exposed. To help overcome this, spiral any new shoots around the post rather than allowing them to go straight up. If there is no new growth, cut off one or two stems in early spring to stimulate the base growth.
Overgrown plants on scaffolding should be refurbished in early spring.
Climbers who dry at the roots are susceptible to powdery mildew, especially honeysuckle and clematis. Keep young plants well watered in the summer, and cover grown plants with garden compost or leaf mold every spring.