Establishment of an annual meadow on extensive green roofs in the UK

This study investigated the establishment of annual meadow including native and non-native species in an extensive green roof in Sheffield, UK. The study aimed to determine the feasibility of establishing annual plant species from a seed mixture and to determine the appropriate sowing rate as well as the necessity of watering during the first growing season from June to November 2006. A 22-species seed mixture was sown on an experimental green roof with a substrate depth of 7 cm using two sowing rates (2 g/m2 and 4 g/m2) and two watering regimes (with and without watering). The watering regime consisted of application of water four times over the course of the experiment. Each combination of sowing and watering regime yielded a successful aesthetic annual meadow green roof. Results showed that a low sowing rate resulted in better conditions for individual plant growth when enough water was available. On the other hand, a high sowing rate was necessary to ensure a sufficient number of plants when water resources were not abundant. The watering regime improved growth in most species; however, it was determined that an annual seed mixture could perform well without watering at the study site. The annual meadow possessed an abundance of flowering plants for an extended period of time; plants started flowering one month after sowing and continued until the end of October. Successful species during the first growing season included Alyssum maritimum, Echium plantagineum ‘Blue Bedder’, Gypsophila muralis, Iberis amara, Iberis umbellata ‘Fairy’, Linaria elegans and Linaria maroccana.

► Establishment of an annual meadow in an extensive green roof is investigated in Sheffield, UK.
► It is possible to establish a long flowering annual meadow without irrigation at 7 cm depth of substrate in the extensive green roof.
► A low sowing rate results in better conditions for individual plant growth when enough water is available.
► A high sowing rate is necessary to ensure a sufficient plant number when water resources are not abundant.
► Watering improves growth in most annual plant species.