Wall-mounted trellis

Fix trellis to the side of a wall or mount it on top to provide climbing plants with an attractive support and to increase the privacy of your garden.

A mass of bright flowers and healthy foliage scrambling up a trellis is one of the most familiar and attractive garden sights. Trellis is generally used to support plants and so soften or ‘dress’ garden walls. It also adds height – important if you wish to create a screen for privacy.

A wide variety of wood and plastic trellis is suitable for wall mounting, from standard rectangular and diamond panels to fan and even arch shapes. Make sure before you buy that the trellis is strong enough to support your choice of plant.

If the climber is deciduous, the trellis must be attractive in its own right as it will be visible in winter. Consider painting or staining bare trellis fixed in a prominent position.

If you need access to the wall behind, select a climbing plant which needs to be pruned hard every year, such as late-flowering clematis, so that maintenance work on the wall can be done in winter. Alternatively, hinge the trellis at the bottom and choose a plant like white jasmine or winter jasmine that remains supple enough to be eased gently away from the wall.

Trellis types

There are two basic types of trellis: rigid framed, heavy duty square-patterned wooden panels; and lightweight, expanding dia-mond-patterned panels, in timber or plastic. Use heavy duty trellis to support dense, woody climbers like wisteria or rambling roses. Lightweight trellis is suitable for less woody plants like some hybrid clematis or climbing annuals such as sweet peas. Wood, the traditional material for trellis, has a pleasing natural appearance. Good quality, heavy duty timber trellis is expensive but it is likely to last for up to 25 years. Timber trellis is usually pretreated with horticultural preservative, so you don’t need to treat it yourself for several years. Plastic trellis is virtually maintenance-free, though it tends to discolour after a few years. Semirigid plastic mesh, sometimes cut to length off the roll, is suitable only for very light support work. Some is sold as clematis support, but will support other lightweight plants. Most plastic trellis comes with its own special wall fixings and full instructions.

Rigid panels in timber come treated with preservative and unpainted. The standard height is 1.8m (6ft), in widths from 30cm to 1.8m (1 -6ft). Rigid panels are suitable both for fixing to the side of and on top of a wall. Expanding trellis opens out like a concertina to make diamond-pat-terned panels in a range of heights and widths. Timber types are generally left unpainted; plastic types come in a variety of colours. Expanding trellis is more suited to fixing to the side of a wall than to mounting on top.

Plant pointers

To estimate how much trellis you need, first check the spread and height of the climbing plant. Then decide approximately what area you want the foliage to cover eventually, and buy a suitable sized trellis panel, or number of trellis panels.

Help a newly planted climber to grip the trellis by loosely tying in the main stem and twining the tips through the latticework.

FIXING WOODEN TRELLIS TO THE SIDE OF A WALL

Battens between the wall and trellis allow plants to wind round the support, and air to circulate. Allow three battens for each standard 1.8m (6ft) high trellis panel. Apply horticultural preservative to all cut and untreated wood before assembly.

FIXING WOODEN TRELLIS ON TOP OF A WALL

When fixing trellis on top of a wall, use 100x50mm (4x2in) thick timber posts to hold the trellis firmly in place. Don’t use battens – they won’t be sturdy enough to bear the weight of the trellis and plants.

Buy post caps too – as well as giving a neat finish, they stop rain water seeping through the cross grain on the top of the posts and rotting the wood.

The length of the posts should allow for the height of the trellis panels plus about 25cm (10in) to overlap the wall and an extra 5cm (2in) on top to take the caps. Buy one more post and cap than the number of panels required.

To calculate the amount of trellis needed, simply measure the length of the wall and divide this by the length of the trellis (usually 1.8m/6ft) to come up with the number of trellis panels required.

Apply horticultural preservative to all cut and untreated wood before assembly.

Self-assembly arches

A self-assembly arch provides the perfect support for climbing plants, and is a quick and easy way to add height and character to a garden.

The three most popular types of self-assembly arches are: wooden, pointed trellis arches; wooden flat-topped pergola arches; and plastic-covered metal arches. All are fairly light and easy to handle, and can be erected on site with the minimum of fuss. Garden centres and some DIY stores offer a selection of self-assembly arches, and there are various mail order suppliers. Trellis arches are simple wooden frames covered with rigid or expanded trellis. Some have hinged tops, allowing you to vary the width of the arch and the pitch of its pointed top.

A trellis arch is ideal for lightweight climbing plants such as hybrid clematis, but isn’t strong enough to support large woody climbers such as wisteria.

Canopy of soft-stemmed climbers such as canary creeper or solanum. One advantage of a metal arch is that you can easily add hoops to extend it. A series of arches makes a stunning walkway or tunnel, reinforced with trained branches of a laburnum or wisteria.

Wooden pergola arches are more robust structures made up from standard pergola components -posts, crossbeams and rafters. Their simple design enables them to sit happily in a modern or traditional style garden.

A wooden pergola arch is sturdy enough to take the weight of woody-stemmed climbers such as wisteria. If you like, you can fill the gaps between the posts with trellis to help support twining climbers such as clematis. Metal arches comprise sections of shaped steel tube, covered in black or green plastic. They come in a range of shapes and sizes, from simple hoops to large elaborate arches with sweeping curves.

Woody stemmed climbers such as wisteria can simply be tied into the horizontal supports, while special mesh infills are available if you want a dense, quickly established arch.

Check the ground

For stability, the feet of all three types of arch need to be set quite deep in the ground, so always check the position of underground pipes and cables first. In soft or recently disturbed ground you may need to secure the feet in concrete.

TRELLIS ARCH

A trellis arch has two side panels and a roof, which you fix together with the nails or bolts supplied. Most trellis arches are Canadian red cedar, which doesn’t need treating with preservative. Depth (from front to back) is typically 60cm (2ft).

PERGOLA ARCH

Made from preservative-treated softwood, a timber pergola arch typically comprises 2.1m (7ft) slotted posts in post spikes, plus 1.8m (6ft) crossbeams and 1.35m (4’/Tt) rafters. You use a sledgehammer to drive post spikes into the ground, so you also need a post spike ‘dolly’ to prevent the sledgehammer dam-aging the spikes. At each stage of construction, use a spirit level to check verticals and horizontals.

METAL ARCH

A plastic-coated metal arch is extremely durable and almost maintenance free. Basic metal arches come in widths from 90cm-2.4m (3-8ft), heights from 2-2.5m {6V1-8’/.ft), and depths from 45-60cm (l1.5-2ft). Tubing diameter is either 2cm or 2.5cm (1 in).

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