Climbers that require discipline
Some climbers are so well-loved that it would be unreasonable to suggest people avoid them altogether. However, to lessen the chances of problems developing, take care when locating these plants and prune them regularly. Tempting though it may be to let climbers intermingle, it is better to keep them separate. If later you decide one must be removed, it is inconvenient to have to unravel mixed plant material, particularly if a thorny plant is involved.
Examples of popular climbers which frequently become rampant are cape honeysuckle (Tecomaria capensis), Japanese honeysuckle (Lonicera japonica), orange trumpet creeper (Pyrostegia venusta), Chinese trumpet vine (Campsis x tagliabuana), coral vine or Mexican rose (Antigonon leptopus) and black-eyed Susan (Thunbergia alata).
Also capable of causing problems are the four climbers listed below. They have been singled out for further description simply because so many people are won over by their beauty but later may regret having planted them in the wrong location.
Bougainvillea is a scrambling shrub rather than a climber, but its strong thorns latch onto any support and help it reach great heights. Those thorns make pruning dangerous, which may explain why many people let bougainvillea grow unchecked.
Pruning ruthlessly after flowering makes bougainvillea blossom more profusely the following season. More importantly, hard pruning removes the long canes, which are of concern if they arch over a neighbour’s wall or your front boundary, since they often descend so low that they can scratch people’s faces.
There are alternatives to having monster bougainvilleas that crush the fence or make corners of the garden inaccessible. Standard forms are commercially available. So, too, are dwarf cultivars that can be container-grown – but remember, the fact that a form is described as dwarf does not mean it needs no pruning.
As with bougainvillea, a disadvantage of many climbing roses (Rosa species and cultivars) is their thorniness. Try to choose an almost thornless cultivar or, if the climbing rose that you want is thorny, plant it where it will not snag people’s skin and clothes. Begin training a climbing rose soon after planting it, being especially mindful of long, unruly canes – bend these to match the direction of growth that you wish to encourage.
Pink trumpet vine
With its glossy foliage and big flower clusters, pink trumpet vine (Podranea ricasoliana) is deservedly popular in many home gardens but, when placing it, you should bear in mind its vigorous habit.
It can send suckers under the neighbours’ fence. It can send arching stems up and over the fence, and they take root wherever they touch the soil. The shoots are strong enough to force fence panels apart, and the growth at the top of the plant – which can reach 3.5 metres in height – is heavy enough to make fences lean.
Being evergreen, this is an ideal a screening plant. As such, it may be better planted on the street frontage rather than on your neighbours’ boundary. Pruning in winter and again in early summer is the minimum requirement, but may not be enough to curb excess growth.
At first, wisteria (Wisteria sinensis) is slow-growing, but then it accelerates. Over many years it spreads extensively and develops thick woody branches. People tend to train wisteria across timber pergolas or veranda fascias because, being deciduous, it casts shade in summer but lets sun in during winter.
If the structure is old or weak, the weight of the plant may bring it down eventually, so check the stability of the support before planting wisteria. Also be aware that as the woody stems thicken over the years, they can force beams apart.
Prune after spring flowering and in autumn to remove soft shoots but, if size is the problem, prune again in winter to reduce the sheer mass. Like bougainvillea, wisteria can be trained as a standard. It will need support and regular pruning in the early years, but the result should be a beautiful feature plant.