Evaluation of the Growth and Thermodynamic Properties of Frankenia on Different Growing Media in an External Green Wall

Currently, the idea of ​​integrating nature and buildings through green roofs and green walls has been considered as a sustainable strategy in cities. However, studies on the substrates which allow the plants to fully establish in these systems are still lacking. It is also a challenge to find the substrates which provide the plants with proper growth, nutrition, and environmental sustainability. This study aimed to evaluate the performance of Frankenia thymifolia in four types of growing media (30% cocopit + 65% perlite + 5% vermicompost, 30% soil + 65% perlite + 5% vermicompost, 30% mushroom compost + 65% perlite + 5% vermicompost and common soil used in the green spaces as the control) in growing conditions of the external green walls. The experiment was conducted as a split-plot in a randomized complete block design with three replications. The main factor was different seasons of the year in four levels and the second factor was the substrates in four levels. The effect of different substrates on thermo-dynamic factors of the substrates and on morphological, qualitative, and water use efficiency characteristics of the plants were significant at the 5% probability level. The results showed that the temperature and humidity of the substrates containing organic compounds were higher than those of the soil. Also, plant height, number of nodes, percentage of coverage, and water use efficiency of the plants were higher in the growing medium containing mushroom compost. Having a high water use efficiency and keeping its qualitative characteristics to an acceptable level in the summer and spring, Frankenia was found to be a suitable species in these seasons. However, due to the cold-induced deleterious effects in winter on these characteristics, it was not a suitable plant species for external green wall systems in climatic conditions of the winter season of Mashhad. Based on this studychr('39')s results, we suggest adding washed mushroom compost to the usual green wall substrate. Frankenia can also be considered a suitable plant for external green walls in spring, summer, and autumn in similar weather conditions to Mashhad.