Galvanized wire and strong plastic-coated wire. This should be pliable but not flimsy, so it can be pulled taut without kinks or sagging. It is usually wound round screws plugged into the wall or run through eyes and attached firmly at each end. Horizontal stretches at 1 ft (300 mm) intervals are usually adequate, but a mesh can be made by doing the same thing vertically as well. If the mortar is good, this can be drilled t ο take the plugs and screws, otherwise the bricks themselves should be used. You will probably need a hammer pow er drill, and certainly a strong masonry bit, to drill the hole as some bricks and mortar can be very hard. This method has its limitations, as already discussed. You also might prefer not to drill the wall.
They can be made from cedarwood or whitewood and should be thoroughly treated before erection. It is obtainable in concertina-like panels which pull open to give a diamond pattern, or in rigid squared panels. Different thicknesses and qualities are sometimes available – the thicker the timber the longer it lasts. Whitewood can be painted but once the plant is climbing up it you cannot paint it again – unless you cut all the climber off before you start. It is manufactured in several widths and lengths and can be screwed directly to the wall or attached to 1½ X V2 in. (40 X 15 mm) battens fixed to the wall first.
All trellis should be fastened to the posts, not the panels, if used against boarded fencing. It is a good idea to fasten it so that it stands off the boards a few inches to allow air to circulate. You can use cotton reels for this purpose, or for any other fixing job where the trellis is required to stand slightly off the wall.
If you feel handy and can afford it, you can make your own trellis by nailing together sawn lathes or roofing battens, which gives you a much stronger job.
This is a plastic version of the wooden sort. It requires no maintenance and is much stronger, but is used in the same way. The squared panels are also made to fold up, which facilitates transporting them home.
Trellis panels can also be used to form a fence for climbing plants using 3 X 3 in. (75 mm sq.) treated softwood or hardwood stakes driven firmly into the ground for 2 ft 6 in. (750 mm), or fastened into Metposts, to which the trellis is nailed. You can strengthen it by giving it thicker top and bottom rails. Trellis panels are available with convex or concave curved top rails for additional effect. Climbing plants can then be grown up this to form a living screen.
Plastic-covered metal trellis
This is rigid or semi-rigid, thin metal rods or wire covered by a substantial coating of plastic. Various designs and colours are available. The semi-rigid sort is bought off the roll by length and it can be obtained in several widths. It can also be used as an open fencing material. The rigid type is usually found as standard-sized panels, though fan-shaped designs are sometimes seen. They are attached to the wall by purpose-made clips supplied with the trellis, the clips being screwed to the wall first. These panels are strong and virtually indestructible as long as the plastic coating is not damaged.
A heavy duty, small gauge plastic mesh which is available in several colours and makes an unobtrusive support against a fence or wall. For installing against a wall it is best attached with metal staples to horizontal battens at 2 ft 6 in. (750 mm) intervals. There are several widths obtainable and the beauty of this method is that you can cover as much or as little of the length and breadth of the wall or fence as you want without the joins showing, as it can be cut to whatever length you want (within reason) off the roll, and joined up widthwise on the horizontal battens.
These are useful for pillar roses (e.g., ‘Golden Showers’) and some twining climbers like clematis and honeysuckle. The poles should be of treated rustic timber or 3 X 3 in. (75 mm sq.) sawn treated softwood or hardwood embedded at least 2 ft 6 in. (750 mm) into the ground, or fastened to metal post supports, and must be of sufficient length to accommodate the plant (usually up to 8 ft (2.5 m)). Site with care as they can look rather obtrusive until the climber is well established. This method can be quite effective at the back of a shrubbery.
All wall shrubs which are unable to support themselves either directly or by clinging to a trellis will need tying in to whatever means is used to hold them to the wall. You should always make sure that the ties are soft enough not to cut into the bark or shoot. Old tights cut into strips are useful for this. If you use plastic coated wire, it should be put fairly loosely around stem and support. Check all ties at least annually, sometimes more with a quick growing variety to make sure they are not getting too tight. Once they have cut into the wood it is too late.