Urban agriculture is important to provide sources of local food for urban residents. Extensive green roofs can be used to provide spaces for local agriculture in these urban environments, although extreme conditions in these environments can be challenging for edible crop production. Moisture in these environments are often the most limiting factor influencing growth and often create problems for urban agriculture activities. Therefore, two culinary herb experiments were conducted on the Southern Illinois University – Carbondale extensive green roof located on top of the agriculture building to evaluate the influences of various water management strategies on resulting plant growth and overwintering. Results indicated weekly irrigation was critical to increase both annual (basil) and perennial (sage and thyme) plant vigor compared to biweekly watering. Although the use of pine bark mulch improved basil growth, sage and thyme growth was not affected by its use. The addition of hydrogels in the medium for water retention did not influence resulting plant growth for either the annual or perennial herbs evaluated. Our results highlight the importance of consistent water supply for growth and overwintering success for both annual and perennial culinary herbs grown in an extensive green roof environment. Although many culinary herbs thrive in dry, well-drained conditions, mimicking their native Mediterranean climate, water management strategies are still important considerations for sustaining culinary herb production on extensive green roofs.
