Walls are always a problem, whether they be the wall of a house, a shed, a dividing wall, or that of an unsightly outbuilding. This is not because it is difficult to cover them adequately, but because of subsequent maintenance. For climbers and creepers, the question of support is of paramount importance.
To be really successful and efficient, the structure on which they are to be trained must have at least as long a life as the climber itself. The condition of the wall, too, is important. On no account erect a screen or trellis on a crumbling wall for before very long it will either fall down or have to be pointed. So before considering climbers make sure that the wall fabric is sound and where high dividing walls are to be covered, see that the coping stones are secure.
One question which is always raised is will the creeper or climber harm the wall? One school of thought insists that clinging creepers such as Virginia creeper and ivy eat into the fabric of the wall. Personally, I have never found this to be the case. In fact, I know of several instances where a covering of ivy has protected the wall of a house for 60 years and when removed the whole wall had to be rendered waterproof. The ivy had protected it and kept the house warm all that time. Certainly, invasive creepers should never be allowed to push under tiles or gutter, as the sheer pressure of growth will cause damage.
Often climbers are planted against a wall without first making adequate provision for their support, with the result that one has to be constantly knocking in nails and tying up the new growths with bits of string as they appear. This does no good at all to the mortar and is a never-ending job.
Any wood used should be treated with a non-toxic preservative, paying particular attention to sawn ends. On no account should crude creosote be used as this gives off harmful fumes and could kill plants. Where possible use red cedar or pitch pine for the main battens. Stone and brick walls absorb heat and provide snug dry shelters for many harmful insects and fungi, so always provide an air space behind the climbing shrub. This will also enable a certain amount of wall maintenance to be carried out.
Before erecting the trellis prepare a number of hardwood blocks, such as oak or beech, soak these thoroughly in a bucket of wood preservative and allow them to dry out. They should then be drilled with a 1/4-in bit and placed between the main batten and the wall. The wall must be drilled with a masonry bit and plugged with a plastic plug. This material can be bought in foot lengths and cut to suit the depth of the hole. The battens are then securely affixed to the wall with 4-in screws. Incidentally, when affixing anything to a wall, I prefer to drill into the solid brick, stone, or cement rather than into the softer mortar or cement between the bricks. This ensures that no damage is done to the fabric of the wall.
Strong growing coarse shrubs such as Cytisus battandieri can be trained and tied directly to a framework of battens. For twining shrubs such as clematis, honeysuckle, or similar climbers, I prefer to cover the whole area with 2-in mesh plastic netting. This material has a long life but if used over a very hot wall or where the heat is intense, the black mesh should be used. One advantage this material has over all others is that any shoots can be quickly and easily secured merely by using ordinary sweet-pea rings.
The method of fixing trellis or plastic netting, as well as the choice of plant and the method of securing, is all-important. The object of planting climbers and creepers is that they will grow up and cover areas but if they are not kept under control they can become unmitigated nuisances.
I receive any number of queries saying that honeysuckles or jasmines have got completely out of hand, weighted down by snow and dragged away from their supports, blown by the wind, or are full of deadwood and what on earth can be done? I am afraid this sort of thing is bound to happen unless adequate and properly-constructed supports are provided.
In fact, I would go so far as to say that if you are not prepared to spend time on the initial preparation of supports then forget all about putting up climbers. This does not mean that walls need not or should not be screened for there are plenty of shrubs that need little or no support and prefer to grow with their backs to a wall.