A plants palette for hydroponic structures on buildings

Establishment of appropriate hydroponic structures is an interesting means of greening buildings, as these can follow any slope, in contact or in a distance from the structural surfaces. In addition to the technical issues associated with the establishment of such systems, the creation of a palette of plants (ornamentals or vegetables) that could cast shade and decorate a particular part of the building is of great interest, as in most situations these structures are widely visible from multiple points of view. The preservation of various plant species with different requirements at a high quality level in a single system is a real challenge. The limits set by environmental conditions both in the air (sunlight intensity, temperature, humidity, wind, etc.), and the root zone (EC, pH, oxygen content, moisture levels, etc.) need to be considered. In this paper, the evaluation of various alternatives regarding the use of ornamental plants in such systems is presented. Plants used in both horizontal and vertical hydroponic planting structures were evaluated. Furthermore, two different closed loop systems of nutrient solution supply, especially designed for this type of hydroponic installations, were used. The plant parameters that have been taken into account to evaluate the two systems were the following: aesthetical and functional properties, performance in closed loop hydroponic systems using a single nutrient solution composition, and finally maintenance demands (irrigation, pruning, plant protection, etc.). The best results were received for Santolina chamaecyparissus, Dimorphoteca sinuata, Rosmarinus officinalis 'Prostratus', Petunia 'Surfinia', Pelargonium capitatum.