Comparison of establishment methods for extensive green roofs in southern Sweden

Prefabricated vegetation mats had higher succulent plant cover than on-site constructed roofs. There was no difference in succulent plant cover between plots established using plug-plants compared to shoots. Shoot-established plots had more moss than the other establishment methods. The commercial substrate 'Roof soil' had significantly higher succulent plant cover than the other substrates, which might be related to a higher nutrient content. The organic content of the non-commercial substrates was rapidly decomposed. The standard species mixture produced a higher cover than both the mix developed for northern conditions and the mix with an increased proportion of big leaved species. The total cover of the plots was mainly dependent on the cover of two species: Sedum album (L.) and Sedum acre (L.). Few species managed to establish spontaneously but the establishment of woody species highlighted the need for proper maintenance.