Abstract Rooftop agriculture is gaining popularity worldwide, although technical challenges, such as restriction on materials used in growing media, can negatively affect plant growth and yields. Incorporating inorganic recycled materials into rooftop growing media offers a promising approach to improving productivity while reducing the environmental footprint of these production systems. In 2022 and 2023, an experiment was conducted at Université Laval (Québec, Canada) to evaluate the performance of different growing media composed of crushed brick, mineralized mulch (MM), and foamed glass (FG), with or without perlite, for rooftop cultivation of tomato ( Solanum lycopersicum ), lettuce ( Lactuca sativa ), basil ( Ocimum basilicum L.), and tiny bok choy ( Brassica rapa subsp. chinensis ). Physical, chemical, and biological properties of the growing media, along with plant growth and yield parameters, were monitored, and results were analyzed using analyses of variance and protected least significant differences ( p < 0.05). Overall, yields obtained with brick‐ and FG‐based growing media were similar to or higher than those of the commercial peat‐based rooftop controls, except for lettuce in 2023. For all species, the addition of perlite to brick‐based media had no significant effect on yield. In 2022, tomato, lettuce, and basil grown in pure FG growing media outperformed those grown in the FG‐perlite mix. In contrast, media containing MM generally performed poorly, likely due to their high pH, which limited nutrient availability and reduced leaf nutrient content. Our results demonstrate the potential to incorporate inorganic recycled materials in rooftop growing media, thus potentially improving its sustainability.
Carrier et al. (Thu,) studied this question.