Sedum Groundcover Variably Enhances Performance and Phenolic Concentrations of Perennial Culinary Herbs in an Urban Edible Green Roof

Abstract

Urban agriculture on green roofs has tremendous potential to enhance food security, economic opportunities, and community building in cities yet faces unique ecological challenges including limited soil moisture content for crops. We compared the effects of two green roof soil moisture management practices, sedum (Sedum album) groundcover versus watering, on performance and quality of three perennial culinary herbs: thyme, mint, and oregano. Individually and interactively, sedum groundcover and watering significantly impacted parameters of performance (biomass, vitality, and module coverage) and quality (total phenolic concentrations) of the three culinary herbs during early stages of establishment while having variable impacts during later developmental stages. Our results suggest that sedum groundcover can serve as a substitute for watering of hardy culinary herbs on green roofs on the basis of plant performance and quality. Findings can be applied to inform agroecological water management of herbs and other hardy specialty crops on green roofs toward enhancing their drought tolerance and advancing sustainable urban agriculture.