The ultimate green house
Planted facades are not a contemporary invention, in fact they have a long tradition. Today there are a number of engineered options for accelerating facade greening, but more on that later.
Building greening has a positive effect on the local microclimate and also protects the facade against environmental influences such as driving rain, direct sunlight and so on. In fact, it can significantly increase the lifespan of the actual facade. Building greening also reduces the pollutant content of the air especially with respect to particulate matter.
The most traditional and easiest way of greening outer walls is using Boston ivy, also known as Japanese creeper or Veitchii (scientific name: Parthenocissus tricuspidata Veitchii). It owes its ability to climb almost any surface without support to the sticky disks that tip its tendrils. The plant is a relative newcomer to our latitudes: it originally comes from Korea, China and Japan and only arrived in Europe in 1860, where it quickly became very popular. It is deciduous with a stunning red colour in autumn (at least in areas in sun) and can easily cover walls measuring 20 metres high in a dense growth. Contrary to popular opinion, the sticky tendrils do absolutely no damage to brickwork. In fact, they protect it against direct sunlight and therefore strong heat gain and large temperature fluctuations. They do not, however, provide any thermal insulation in winter.
The Veitchii is closely related to the Virginia creeper (Parthenocissus quinquefolia), although the latter usually needs a climbing support due to its poorly developed sticky disks. There are, however, a number of varieties that are also good climbers such as Parthenocissus quinquefolia 'Engelmannii'. All varieties have the typical red autumn colour.
Another well-known greening plant is ivy (Hedera helix). Its leaves keep their green colour on into winter. It climbs using holdfast roots and can also cover walls up to a good 20 metres high. It can, however, become very thick, especially at the top, when it matures. If snow then builds up on it, it is not unknown for entire facades to be stripped and for substantial damage to occur. So a facade greened with ivy must be kept under control and the ivy secured with wire ropes at the top at least. The ivy must not be allowed to grow onto the roof either, since its shoots can easily move roof tiles.
Almost all other climbers we have need climbing aids in the form of a framework or wire ropes. One of the most attractive plants, at least during the flowering season, is wisteria or Chinese wisteria (Wisteria sinensis). It is an extremely lush climber and is both fast and high-growing (30 metres). The first lush flowers appear before the leaves shoot. Keeping it in check is time-consuming, however your efforts will be rewarded by a profusion of flowers once or often twice a year, even if they are short-lived. Be careful with gutters and downpipes, though, since wisteria can encircle and actually crush them.
Climbing roses can be magnificent, but seldom reach heights of more than 5 metres. The same goes for the many varieties and hybrids of clematis. Those from the Viticella group in particular are not only hardy, but also have a long flowering season, often keeping their flowers on into August.
There are numerous other largely hardy climbers that do grow here, but are more rare to find: climbing hydrangea (Hydrangea petiolaris), pipevine (Aristolochia macrophylla), trumpet creeper (Campsis radicans), honeysuckle (Lonicera) in many shapes and varieties, hops (Humulus lupulus), winter jasmine (Jasminum nudiflorum), chocolate vine (Akebia quinata) and more. The kiwi fruit (Actinidia deliciosa) also thrives here and is hardy in sheltered sites, however it grows very vigorously and is better suited to large pergolas than for wall greening. The same goes for the silver lace vine (Faloppia aubertii) often seen on noise-insulating walls.
There are also numerous other plants, mostly annuals for us, that are very attractive when used to green small areas like terraces and balconies: cup-and-saucer vine (Cobea scandens), black-eyed Susan vine (Thunbergi alata), morning glories (Ipomea in many types and varieties), nasturtium (Tropaeolum hybrids), runner bean (Phaseolus coccineus), sweet pea (Lathyrus odoratus),
A very old method of facade greening is using espalier fruit trees. The focus here is not on greening, but rather producing a harvest in harsher climates like the Forest Quarter region of Austria. Fruit trees that would struggle to thrive outdoors can be grown on a framework on the southern-facing walls of houses, where the climate is more favourable. Some regions have a great tradition of this, for example Salzkammergut in Austria. Grape vines are also traditionally frequently grown on house walls outside of wine-growing climates, and therefore also count as facade greening.
While the aforementioned plants root in the soil at the base of the greened wall, engineered greening systems where the plants grow in "containers" of various shapes fastened to the wall have become more popular in recent years. These systems can be used to green even large and high surfaces quickly. However, the time and cost involved in setup and maintenance is considerable. While these forms of greening have become well established in countries that do not have periods of frost, they are more rare at our latitudes. Once the water supply has to be shut off and the lines drained in autumn to protect them against frost, long periods of frost can result in the plants drying out ("frost drought"). Ensuring the watertightness of the facade to the inside can also sometimes cause major problems.
Prof. Karl E. Schönthaler
VIKING garden expert
Marvellous green facade in Avignon, France.
Like at that hotel in the German town Würzburg, the brickwork is not damaged, but protected.
Ivy and wisteria are real climbing artists – as in that shot at a villa in the Austrian capital Vienna.
A villa in the Veneto region, Italy: Greenings protect facades from direct sunlight and precipitation.