Location Factors and Plant Selection

When planted near facades, climbers, roses, grapevines, and fruit trees have specific needs that must be taken into account when choosing a location. Learn here about the determining factors for successful façade greening and the general things to keep in mind when choosing a location for your plant. Based on this information you can assess the position and aspect of your garden, select the most suitable climbing plants or, if necessary, adjust some of these factors so that a preferred plant species can gain a foothold and even thrive in a less than optimal location.

Most climbing plants, like these morning glories, like protected spaces.
Most climbing plants, like these morning glories, like protected spaces.

Light and Heat

Plants need light to develop flower buds. But equally so, they need the heat radiated from the sun. Full sun on a brick wall allows a microclimate to develop which will produce an abundance of flowers and fruit, the like of which you will not get in a freestanding 'open' position. The wall stores the heat and radiates it during the evening hours, which further promotes the ripening of the fruit. On wooden houses and those with external insulation, this "oven" effect is also present, though to a considerably less degree.

 

Unfortunately, a lot of heat also increases the evaporation rate and thus water consumption. Some plant species become very susceptible to fungal attack under heat stress.

 

In order to determine the duration of sun exposure on a wall, take a sunny day in early May or late August as a reference to get a realistic, average value. We suggest the following:

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

 

The southeast or west walls can be considered as "exposed" locations.

Wood house with grapevines

Temperatures emanating from a wall are also influenced by the wall colour. Dark walls heat up the rising air considerably.

Building greening with espalier fruit

Walls of a light colour allow the plants to use the light more effectively, because the foliage at the back receives "mirrored" light-- light reflected off the wall, which improves the plant's overall assimilation.

Talut walls in Radebeul / Saxony

Old, roofed Talut walls. Here, even the back side with less sun was planted with espalier trees.

Greened house wall with roof overhang

Wide eaves are initially regarded as "protection" for green façades, but the planted area then often receives little rain water.

Surface greening with fleece vine

This image depicts 4 approx. 7m tall trellises planted with silver lace vine (fleece 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-- thus, its foliage is still green and dense.

Wind

Open areas next to stand-alone buildings are always exposed to winds and not particularly suited for climbing plants; in such environments they lose a lot of water through evaporation. Much better for these plants are locations where a windbreak is created by elevations (mounds), surrounding buildings, or shrubs/groves. Urban locations can almost always 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/loam 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 by depth (based on the roots' abiity to penetrate it): deep soils (min. 75 cm), medium depth soils (35-45 cm) and shallow soils (only 15-25 cm).

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 6-10 cm deep layer of mulch, consisting of either leaf litter, straw, grass clippings... which is replenished regularly.

Building with grapevine greening

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.

Espalier garden in Potsdam / Brandenburg

Fruit growers have made good use of the "oven" effect for centuries by building so-called "Talut walls" (freestanding roofed walls).

A "cold air lake" condition

A façade greening in 'full sun' though located in a depression. In valleys and low lying ground where the air cannot flow out (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.

Dog urine on plant pit

Plantings within street zones are particularly vulnerable to being used as a dog urinal.

Water

Climbing plants tend to have a drying effect on foundation walls, which in earlier times was a commonly used technique for the greening of buildings. For example, a single grapevine has to absorb and evaporate 500 liters of water to produce 1 kg of dry matter (which equates to about 2 kg of wood or 10 kg 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 out, the roots will atrophy there, and other roots will grow towards the nearest available moisture source. However, such natural soil moisture and also the deeper groundwater are usually only sufficient as an "emergency supply" 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 in the vicinity of plants that consume large amounts of water and nutrients, their development may be considerably thwarted. A root barrier-- made from either foil, stone slabs, large pavers, or using a large plant container with the bottom either perforated or knocked out-- will solve such problems. Even smaller undergrowth plants can hinder the climbing plant in the initial growth phase. 

High greening with Wisteria

Tall façade greenings are more exposed to the winds than low ones. Something to consider in regard to water supply!

Cobblestone ring

Planting areas 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.