Location / Position and Aspect

Climbing plants, grapevines and espalier fruit have quite specific requirements as to where they grow, ie location and aspect. The following text describes the determining factors for successful façade greenings in Central Europe. Based on this information you can assess yourself the position and aspect of your garden, select the most suitable Climbing Plants or, if necessary, adjust some of these factors in order to let  a preferred plant species thrive even in a less than optimal location.

Most climbing plants like these morning glories like protected spaces.

Light and Heat

Plants need light to develop flower buds. Just as importantly though, they need the heat radiated from the sun: full sun on a tiled wall creates a microclimate which will produce an abundance of flowers and fruit in your plants, the like you will not get in a freestanding position. At the same time, the wall stores this heat and emanates it during the evening hours, which further promotes the ripening of the fruit. In timber houses and houses with external heat insulation, this "oven" effect also exists, although to a significantly lesser degree.

Unfortunately, a lot of heat also increases the evaporation rate, hence the water use. Furthermore, some plant species become very susceptible to fungal attack under heat-stress.

In order to establish the duration of sun exposure on a wall, a sunny day in May or August should be taken as a measure to get a realistic, average value. We suggest the following classification:

1.         8-12 hours: full sun exposure, full sun

2.         5-8 hours: sunny

3.         2-5 hours: semi-shade

4.         0-2 hours: full shade to minimal sun exposure

It follows that even a southeast or a west wall can still be an "exposed" location.

Temperatures emanating from a wall are also influenced by the wall colour. Dark walls heat up the rising air strongly.
Wood house with grapevines
Walls of a light colour allow the plants to use the light less stressfully, because the foliage at the back receives "mirrored" light ie light reflected off the wall, which improves the plant's overall assimilation.
Building greening with espalier fruit
Old, roofed Talut walls. Here, even the less sunny side was planted with espalier trees.
Talut walls in Radebeul / Saxony
Wide eaves are initially regarded as "protection" for green façades, however the planting area often receives but little rain water.
Greened house wall with roof overhang
This image depicts 4 approx. 7m tall trellises planted with Silver Lace Vine along a sunny east-facing wall, in early autumn. The plant to the far left grows in semi-shade, which means it has to tolerate much less heat. Hence its foliage is still green and dense.
Surface greening with Fleece vine

Wind

An open area is always exposed to winds and is not particularly suited for climbing plants, because their evaporation becomes excessive in such environments. Much better for these plants are locations protected from the wind, ie areas protected from strong winds either by mounds, surrounding buildings or a grove. In the cities, most locations can be classified as "wind-protected."

Soil

Garden soil rich in humus is the optimal growing medium for climbing plants, and usually, the addition of a small amount of crumbly clay improves the soil further. However, a high groundwater table (say between 0.5m -1m) or a layer of clay below can lead to serious waterlogging.

Soils are also classified based on the roots' strength and ease to penetrate into it, ie deep soils (min. 75cm), medium depth soils (35-45cm) and shallow soils (only 15-25cm).

Mulch

Most climbing plants originate from forests and forest edges, hence they appreciate a protected, moist soil environment which is subject to only minor variations in soil temperature. In the forest, the natural mulch or leaf litter ensures even soil temperatures, however in the case of façade greening projects, such an even microclimate must be established first. This is achieved with a 6-10cm deep layer of mulch either consisting of leaf litter, straw, grass clippings or similar, and which is replenished regularly.

For this wall the daily sun exposure of 6-7 hours is just beginning. The building wing to the left provides additional protection from the wind which the grapevines love.
Building with grapevine greening
Fruit growers have made good use of the "oven" effect for centuries by building so-called Talut walls (freestanding roofed walls).
Espalier garden in Potsdam / Brandenburg
A façade greening in "full sun," though located in a depression. In valleys and low lying ground where the air cannot flow out ie is trapped, cold air accumulates at night ("cold air lake"). Such areas often remain cooler than their surroundings for several hours into the day. Under these conditions the frost hardiness of plants is really being put to the test, however with the right plant species selection such a situation can be somewhat prevented.
Area "Kaltluftsee"
Plantings within street zones are particularly vulnerable if they are being used as a dog urinal.
Dog urine on plant pit

Water

Climbing plants tend to have a drying out effect on basements, which in earlier years was a commonly used technique. For example, a single grapevine has to absorb and evaporate 500 liters of water to produce 1kg of dry matter (which equates to approximately 10kg of fruit)! The widely branching surface roots will suck up all the rainwater first, while the deeper roots search for any lower lying soil water. If an area is drying up, the roots may die there, and other roots will grow towards the nearest available soil moisture.

However, such soil moisture is usually only sufficient for "emergencies" or during times of drought. Hence, due to the "oven" effect along walls, most climbing plants require regular watering!

Root Competition

If climbing plants are planted within the root zone of large shrubs or trees or within the root zone of plants with a huge uptake of water and nutrients, their development may be strongly impeded. A root barrier made from either foil, flag stones or large pavers, or using a large plant container with the bottom either perforated or knocked out, will solve such problems.

Tall façade greenings are more exposed to the winds than low ones. Something to consider in regard to water supply!
High greening with Wisteria
Planting beds along walls and houses are usually extremely dry - which is good for the foundations. However, it is usually better to prepare the planting area about 0.5m - 1m away from the wall, so that watering can be done freely in the future, without any impact on the walls.
Cobblestone ring