Media depth influences Sedum green roof establishment

Species selection and initial establishment of plants is critical for long term survival and health of green roofs. Plants that can withstand harsh environmental conditions and provide rapid coverage on extensive green roofs can reduce erosion, limit weed invasion, and provide a more aesthetically pleasing roof to satisfy customers. This study evaluated the effect of green roof substrate depth on initial establishment of 12 Sedum species in a Midwestern US climate. Plugs of 12 Sedum species were planted on 8 June 2005 and evaluated bi-weekly until first frost for absolute cover (AC) using a stainless steel point-frame transect. Most species exhibited greater growth and coverage at a depth of 7.0 and 10.0 cm relative to 4.0 cm. AC was highest for Sedum sarmentosum at all depths, but this species may be too aggressive. Other suitable species include Sedum floriferum, Sedum stefco, and Sedum spurium ‘John Creech’. In general, species that are less suitable are Sedum ‘Angelina’, Sedum cauticola ‘Lidakense’, Sedum ewersii, Sedum ochroleucum, and Sedum reflexum ‘Blue Spruce’. For the species tested, a minimum of 7.0 cm is highly recommended. With shallower substrates, S. sarmentosum and S. stefco will provide the fastest coverage. This paper is a portion of a M.S. Thesis submitted by K.L. Getter.