This inquiry is about the accepted non-native sedum based plant mix that will meet credit requirements for green roof system. The facility is located in Boston MA area, USDA Plant Hardiness Zone 6a. Native New England is heavily forested, relatively damp and contains soil with high organic content. A roof top in New England is in full sun, windy, dry and includes mostly inorganic lightweight minerals for soil media with relatively low organic content. Based on this most native species will not survive the rooftop environment without significant levels of maintenance including regular watering and fertilization. The sedums, succulents and other hardy plants that compose traditional green roof plant palettes are ideally suited for the New England rooftop climate. They would be the lowest maintenance for a green roof system, requiring no permanent irrigation, limited fertilization (annual slow release only), no herbicide or pesticide treatments and overall minimal attention from humans. The green roof system we are asking for acceptance on is: Primary - system 15% Sedum spurium, Dragon\'s Blood 15% sedum kamtschaticum var., floriferum, Weihenstephaner Gold 15% Sedum album, Murale 15% Sedum ternatum, (North American native) 10% Sedum oreganum, (North American native) 10% Sedum rupestre, Angelina 10% Sedum spurium, John Creech 10% Sedum kamtschaticum Secondary - system - 25% of the primary palette to be replaced with mix of at least two of the following: Allium schoenoprasum (North American native) Opuntia humifusa (North American native) Sedum cauticola, cauticola Lidakense or cauticola Betram Anderson Sedum reflexum Sedum spurium Tricolor
The project is inquiring about the acceptability of a non-native plant mix for their vegetated roof. While the stated plant list (predominantly varieties of sedum) meets the definition of native/adaptive, it does not meet the SS Credit 5.1 intent of providing habitat and promoting biodiversity. While a number of sedum varieties are proposed, the planting is still essentially a monoculture of species similar in size and lacking in habitat value. The proposed extensive green roof approach could be used towards achieving SS Credit 5.2. Applicable Internationally.