Urban green can be complemented by Living walls (LW). Knowledge of LW, including technique or their cooling effects, is well discussed, but little published data on plant diversity, design and development in LWs exists. The plants themselves determine whether LWs achieve their intended benefits. However, LW plants are exposed to extreme conditions such as temperature or drought stress.
Therefore, we observed plant development in a textile-based LW (mat) over a three-year experiment under a temperate oceanic climate in the south west of Germany. The aim was to establish higher plant diversity for use in LWs. We chose 34 perennials (shrubs, ferns, grasses, and geophytes) that require high soil moisture. The mat was soil-free and had to be overwatered with a nutrient solution. The perennials were grouped in the plant module “cascade” (tall, hanging plants) and “ground cover” (low-spreading plants). We created four experimental walls exposed to the south, north, west, and east and adapted the plant modules to the lighting conditions of the experiment wall. The modules were pre-cultivated and attached to the experimental walls in a randomised design and repetition of four. We determined the visual attractiveness and additional parameters of individual plants.
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We saw differences in winter survival rates depending on minimum temperature in winter. The tested plants developed a special vertical growth form and height. We observed various results at different expositions but found suitable species for each exposition. With these results, we derived a table of plants along with their suitability for LWs and determining conditions.