Application of green walls still has not attracted interest among the contractors and people, and this can be due to poor growing performance of the plants on these systems. This study investigated the effect of four growing media types (30% cocopeat + 65% perlite + 5% vermicompost, 30% soil + 65% perlite + 5% vermicompost, 30% mushroom compost + 65% perlite + 5% vermicompost and regular soil as the control) on the performance of three plant species (Frankenia thymfolia, Vinca minor, and Potentilla sp.) on green walls under arid climate of Mashhad city in Iran. In the control growing medium with no organic matter, Frankenia maintained the highest moisture and the lowest temperature compared to the other growing media types. The growing media did not affect the root and shoot fresh and dry weight and leaf relative water content of the Frankenia. Vinca minor in the cocopeat and mushroom compost produced the highest root fresh and dry weight; however, changing to the growing media types enriched with organic matter content did not affect the shoots fresh and dry weight of this plant type. The growing media containing organic matters compared to the control growing medium, improved relative water content of the Potentilla leaves. The growing media containing organic matters, especially mushroom compost, had positive effects on improving the growth performance of the green walls, through maintaining the moisture content of the media, and thus the relative water content of the leaves, which enhanced vitality of the plants.

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