Climbing and Wall Shrubs

Walls and fences offer gardening opportunities that are not to be missed. They can provide a home for climbing and wall shrubs, while the extra protection offered by a south-or south-west facing wall enables you to try a few exotic shrubs that might otherwise fail in our climate. In smaller gardens, walls and fences have another important advantage: they allow you to exploit tall-growing plants without greatly increasing the amount of existing shade.

A few climbers, such as ivy, are self-supporting, attaching themselves to brick-work or weathered timber with special roots. Others, such as vines, produce tendrils to grab any available hold, or twine their stems around a support in the manner of honey-suckle. Yet another group thrust or scramble their way upwards through undergrowth, sometimes using curved thorns or spines to hang on to other plants, as wild brambles do in hedgerows.

Apart from those that attach themselves directly to a flat surface, the shrubs will need the support of trellis, plastic-coated mesh panels, or a series of horizontal wires fixed to a wall or fence; or the shoots can be tied to individual nails driven into appropriate points as the plants increase in height and spread.

Many climbers can be trained up vertical posts and tripods of poles – or even up an existing large tree. And if space is available a pergola (made up of pairs of vertical posts in line and connected along their tops by horizontal timbers) can make an exceedingly attractive feature when clothed with a variety of climbing plants.

There is also a large group of plants which, while not strictly climbing in habit at all, can conveniently be trained flat to give a fine display.

Some gardeners are worried that self-clingers, such as ivy or Virginia creeper, will do structural damage to walls. There is some cause for anxiety if it is an old building where the bricks are bonded with lime mortar; but modern structures built with cement mortar should be safe if the building is sound, with crack-free walls. In any event, never allow plants to invade the gutters and roof.

Selection

Ivy (Hedera) is one of the most useful yet under-rated climbers; it is self-supporting, undemanding, and grows just about any-where. Our native ivy (H. helix), which often appears of its own accord, has many attractive cultivars. Among the best are ‘Buttercup’, with bright yellow leaves when grown in sun; ‘Gold Hearf, whose green leaves have a central splash of gold; and ‘Glacier’, a small-leaved form with silver-grey foliage edged white, which is often sold as a houseplant. Variegated Persian ivy (H. colchica ‘Dentata Variegata’) is especially ornamental; it has very large leaves marked with green, grey, and yellow.

The Virginia creeper (Parthenocissus quinquefolia) and the Boston ivy (P. tricuspidata ‘Veitchii’), with which it is often confused, are both self-climbing and give glorious crimson autumn leaf colouring, but they do need a lot of space to romp over. Much more restrained (but also less hardy) is the Chinese Virginia creeper (P. henryana), another self-clinger, which should be grown in semi-shade to bring out its beautiful silver and pink leaf colouring in summer; it also has good autumn leaf colour.

imageMost garden hydrangeas are bushes, but a Japanese species, Hydrangea petiolaris, is a climber as self-clinging as ivy, with large, creamy white Lacecap flowers in June, although it usually takes at least five years from planting even to begin to think of blooming. Finer still is the related Schizophragma integrifolia, which behaves in the same way and looks similar to the climbing hydrangea, but flowers in July. Although both these species will grow and flower on north- and east-facing walls, their display is better if they enjoy some sun.

Pileostegia viburnoides, another self-clinger related to the climbing hydrangea, has two great assets: first, it is slow growing and easily accommodated on even a bungalow wall; second, it is an absolutely hardy ever-green that can be grown on a wall facing in any direction. It has rather narrow, pointed leaves up to 150 mm (6 in) long and tiny, creamy white flowers that are carried in crowded clusters to form heads some 100-150 mm (4-6 in) across in September. It is not the most spectacular of plants, but is a very useful one owing to its late flowering season and its acceptance of a shady wall.

I have put the trumpet vines (Campsis) last of the self-clingers because many people have been disappointed with them. It is not that they are especially difficult to grow, but they flower reliably only in a long, hot summer. For this reason they are not worth attempting away from a warm, sunny wall or in colder areas of the country. Given the right conditions, however, their effect is sensational. The best one is probably the hybrid C. x tagliabuana ‘Madame Gallen’, which produces 75 mm (3 in) salmon-red trumpets in August and September. It can be pruned hard in February or March.

clematis macropetalaAmong those plants that grasp their supports, the clematis, which hold on with their leaf stalks, are the most popular. The large-flowered forms can be had in colours of purple to blue, carmine to pink, and white. All do best when their roots are in moist, shaded ground. In addition there are a number of species which, although they have smaller flowers, carry far more of them and can be delightful. They include the May-flowering, white Clematis montana, and its pink-flowered cultivar ‘Rubens’, which has bronze-green foliage; C. macropetala, with double blue flowers in June and July, which also has a pink form, ‘Markhamii’; and C. tangutica, which carries masses of little yellow blooms from July to October if it is pruned gently.

Clematis pruning is a subject that worries many gardeners, since the plants are in flower for so much of the year. The small, spring-flowering ones, such as C. montana, should be dealt with immediately after blooming by cutting out their flowered shoots. Large-flowered clematis that bloom mainly in May and June are dealt with in late February or March by removing all dead wood and cutting back the shoots to the first pair of plump, green buds. The other clematis – those that bloom mainly after mid-June – are also dealt with in February or March, generally by cutting all growth hard back to leave 1m (3-1/4 ft) or less above soil level.

The climbing honeysuckles (Lonicera) are old favourites and many are worth growing for their scent alone. Among those with the brightest flowers are the early Dutch (L. periclymenum ‘Belgica’), with purple-red and yellow flowers in May and June; and the late Dutch (L.p. ‘Serotina’), with purple-red and creamy white flowers in July to September. The blooms of the much less common Chinese woodbine (L. tragophylla) expand to about 50 mm (2 in) long and 25 mm (1 in) wide across the mouth; they are bright red in bud and yellow-tipped red when open. This species is scentless, and it needs a shady site and moist soil. All the above Lonicera are deciduous. Of the evergreen forms, grown for their foliage, one of the best is the Japanese honeysuckle (L. japonica ‘Aureo-reticulata’), whose leaves are netted with bright gold. Its fragrant white or pale-yellow flowers bloom from June to October.

Another twining climber grown for its foliage is the deciduous Kolomikta vine (Actinidia kolomikta). The young leaves are purplish at first, turning to green, but many develop bright white and pink variegation over part of their surface. It seems that warmth brings out this colouring, so the plant is best sited against a south or west wall in full sun. One could not claim that it makes a bright display (its small white flowers appear in June), but I find it pleasing and it is certainly unusual. This is not a vigorous climber, usually reaching no higher than 3.7m (12ft). A word of warning: the plant seems to hold some special fascination for cats, so if you plant one, give it anti-cat protection while it is young.

One of the fastest-growing deciduous climbers, the Russian vine (Polygonum baldschuanicum) – also known as the mile-a-minute vine – is just the thing for covering a garden eyesore quickly. It is rampant, adding as much as 4.5 m (15 ft) in a year, but it is very handsome when covered with its long, pinkish plumes of flowers in July to September; the flowers darken as the fruits ripen, maintaining a display until October. The related P. aubertii closely resembles the commoner Russian form, and is I think more attractive, having white or greenish plumes until the fruits begin to ripen.

One or two true vines make very attractive climbers. Perhaps the most spectacular is Vitis coignetiae, with its huge leaves, as much as 300 mm (1 ft) across, that are green above and rusty brown below, and turn brilliant shades of red in autumn. The species is, however, too vigorous for anything less than a lofty tree or large house. Of more modest habit is the grape vine, Vitis vinifera. One of its cultivars, ‘Purpurea’, has foliage that turns purple in summer; another, ‘Brandt’, makes a superb show of autumn colour (orange, crimson, and pink) and also provides grapes good enough to eat in a warm year if it is grown against a wall.

If you have space available along a sunny wall, two of the best-value flowerers are members of the potato family (Solanum), which you will easily recognise from their clusters of flowers. The Chinese potato tree (S. crispum), best in the form of its cultivar ‘Glasnevin’ (syn. ‘Autumnale’) has flowers of a rich blue with a yellow centre that open in sequence throughout the summer. Hardier than the type species, it may be killed to the ground by frost, but it will spring up again the following season. If the top growth is not killed, however, it may start to bloom as early as May. ‘Glasnevin’ is better described as a scrambler than as a climber: you will need to support its new-season shoots. The other recommended member of this genus is the jasmine nightshade (S. jasminoides ‘Album’), a robust twiner that can put on 3.7 m (12 ft) of growth in a season, but is slightly more tender and liable to be cut by frost. It too carries its flowers, which are white, all summer long. Both have the advantage of flowering well in their first season from planting.

The deservedly popular Chinese wisteria (Wisteria sinensis), with its long hanging clusters of mauve pea-flowers, makes a delightful display in May and June. Having even longer flower racemes, the show put on by W. floribunda ‘Macrobotrys’, a form of the Japanese wisteria, can be breath-taking when trained to an arch or pergola. Both of these twiners will climb any suitable support, but like the honeysuckles they should not be put on a tree or a shrub or they may eventually strangle its branches.

Roses are, perhaps, the most popular of the non-self-supporting climbers. They are not the best plants for a hot, sunny wall (where one so often sees them) because they almost inevitably suffer from mildew there. In any case, I think that such a favoured site is better reserved for something more un-usual. Roses can be grown on pergolas, up pillars, or fanned out on a fence or trellis screen. Most suitable for pillars, I find, are the ramblers, since most if not all the old shoots are removed at pruning time and the new ones can be spiralled around the support. There are so many roses available that it is mostly a matter of picking the colour you prefer.

Although usually seen growing against a wall, the winter-flowering jasmine (Jasminum nudiflorum) is perfectly hardy and can be grown as a shrub in the open. It makes a spectacular sight, however, if it is neatly trained to a flat surface; the young shoots arch from it and are bejewelled with yellow flowers from November to March. Hard frosts may kill the open blooms, but they are quickly replaced by the unharmed buds. This is certainly one of the most valuable of all winter-flowering shrubs for colour.

Common jasmine (J. officinale) carries clusters of white, deliciously scented flowers at its shoot tips from June to September. Unlike its winter-flowering cousin it is a vigorous-growing twiner and needs the protection of a sheltered corner in really cold districts. The best form to buy is ‘Affine’, which has slightly larger, more numerous flowers that are usually tinged with pink on the outside. Although it can be trained over a support, it usually looks better if it is allowed to scramble naturally among trees and shrubs.

Another yellow flowerer, the Jew’s mallow (Kerria japonica), produces long, arching, green-barked stems that can be fanned out against a fence or shed. Its best-known cultivar, ‘Pleniflora’ (’Flore Pleno’), has double orange-yellow flowers that are more attractive than the single blooms of the type species. Again, these plants are not strictly climbers. Height is normally about 2 m (6-1/2ft), but can be more against a wall. The blooms appear in April and May at the ends of the previous season’s shoots.

Perhaps the most spectacular of all wall shrubs is the magnificent evergreen Magnolia grandiflora. Its huge bowl-shaped, creamy white flowers open sporadically from July until the cold October weather puts paid to any remaining unopened buds. Anyone who has seen and smelled these gorgeous blooms on a tree or stretching up for perhaps three storeys on an old building probably imagines that such a delight would be beyond the scope of someone with a modest-sized house. And if you had a young plant of the ordinary species you would probably be right; indeed, you could easily wait 30 years or more to see a flower at all. But if you buy a plant of the ‘Exmouth’ form, or possibly better still one of ‘Goliath’, it could be flowering within five years and be no more than 1.5 m (5 ft) high. In common with all magnolias the plants should be set out in May, working plenty of peat into the soil beforehand and packing more around the roots at planting time. Magnolias are an exception to the very-firm-planting rule since their fleshy roots are easily damaged. Being evergreen, the cultivars mentioned need some shelter to protect the attractive, glossy foliage from wind damage; their flowering performance will be enhanced if they get plenty of sun to ripen the new growth each year.

Other common shrubs which can be trained up supports include the flowering quince (Chaenomeles) and Garrya elliptica; Forsythia suspensa; the firethorns (Pyracantha), which carry hugh crops of red, orange, or yellow autumn berries; and the decorative brambles (Rubus). All are easy to grow.

04. July 2013 by admin
Categories: Climbers, Plants, Shrubs | Tags: , , , | Comments Off on Climbing and Wall Shrubs

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