Rooftop vegetable production using growing media with limited organic content

A. Riani, M. Dorais, G. Grégoire
Urban agriculture is currently experiencing a significant boom in Canada and in other countries. Rooftop vegetable production is a relatively new method of food production and has been gaining in popularity in the last few years. However, several challenges are associated with this production method. For example, in Quebec, local building codes restrict the use of organic materials on roofs, which affects growing media properties and plant performance. The objective of this project was to develop growing media adapted to rooftop vegetable production, while respecting the building code as well as the Canadian organic production standards. To do so, we established 32 plots of 1.50×1.0×0.25 m arranged as a completely randomized design with four replicates located on an experimental green roof and perched at 3 m above ground level. The impact of eight growing medium treatments (6 mixture treatments composed of different portions of perlite, sand, loam, peat, and coir + 2 commercial controls) on growth, yield and plant mineral content of three varieties of lettuce and one variety of tomato was evaluated during two growing seasons. The growing medium chemical properties as well as the microbial activity were evaluated at different times during the experiment. The studied growing media resulted in tomato yields similar or higher than the controls, but no significant effect was observed for any of the lettuce varieties. Despite the relatively short duration of this experiment, significant changes in pH and EC were observed in the different growing medium. Overall, our results showed that it is possible to develop performing growing media adapted for rooftop vegetable production.
Riani, A., Dorais, M. and Grégoire, G. (2024). Rooftop vegetable production using growing media with limited organic content. Acta Hortic. 1389, 417-426
DOI: 10.17660/ActaHortic.2024.1389.49
rooftop, vegetables, growing media, organic farming

Acta Horticulturae