Media depth influences Sedum green roof establishment

Abstract

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.

Substrate Composition and Depth Affect Soil Moisture Behavior and Plant-Soil Relationship on Mediterranean Extensive Green Roofs

“…In addition to substrate composition, increasing substrate depth generally improves the growth and survival of green roof plants by increasing the availability of water and nutrients, especially during periods of drought [18,25,73,79]. At the same time, high vegetation cover on green roofs helps improve water retention [42,80,81].…”

Carbon sequestration potential of green roofs using mixed-sewage-sludge substrate in Chengdu World Modern Garden City

“…Generally, deeper green roof substrates can display higher root protection and moisture retention from temperature fluctuations, while they also provide more vertical space for plant root growth before reaching the root barrier (Durhman et al, 2007). Among green roof depths of 4.0, 7.0, or 10.0 cm for three roof platforms, most of 12 Sedum species in a Midwestern U.S. climate exhibited greater growth and coverage at a depth of 7.0 cm and 10.0 cm relative to 4.0 cm, while a minimum green roof substrate depth of 7.0 cm is highly recommended for the species tested because the fastest coverage was provided by S. sarmentosum and S. stefco with shallower green roof substrates (Getter and Rowe, 2008). At 20 cm depth of green roof substrate (compared to 10 cm substrate depth) on three green roofs in the U.K., the greatest survival, diversity, size and flowering performance of planted species was observed (Dunnett et al, 2008).…”

“…S. 'Angelina', S. cauticola 'Lidakense', S. ewersii, S. ochroleucum, and S. reflexum 'Blue Spruce' are less suitable among 12 Sedum species, and highly recommended for the species tested was a minimum of 7.0 cm substrate depth. In addition, S. sarmentosum and S. stefco will provide the fastest coverage with shallower green roof substrates (Getter and Rowe, 2008). Landscape systems had higher carbon content than other landscape systems, such as more woody plants and shrubs (65.67, 78.75, and 62.91 kg C m À2 ), herbaceous perennials and grasses (68.75 and 67.70 kg C m À2 for the in-ground and green roofs, respectively) (Whittinghill et al, 2014).…”

Initial agronomic performances of Mediterranean xerophytes in simulated dry green roofs

“…The Mediterranean environment is rich in native species adapted to moisture stress and would therefore appear to provide much choice for species to be used in green roofs in dry ecosystems, together or in alternative to the traditional Sedum species. However, while it is known (Getter and Rowe 2008) that Sedum can thrive with low substrate depths (70 mm), no information on substrate depth is available for other Mediterranean species. In a study conducted in the UK the necessary substrate depth for species suitable for green roofs varied between 200 and 300 mm.…”