A suitable plant species for SCV roofs consist of the following features: drought tolerant, minimal root structure, minimal height, ability to form a vegetative mat, non-rangy, heat tolerant, frost tolerant, and the ability to adapt to a non-traditional soil media. Plant species that have extensive root system and tend to be rangy can puncture waterproofing elements or grow into unwanted areas causing mold and mildew. Water, high nutrient, and shade-dependent plants are not suitable for SCV roofs and should be avoided and can lead to expensive failures.
Some of the most successful SCV roof plant species are in the families Crassulaceae and Aizoaceae, which are CAM plants. A plant that uses the crassulacean acid metabolism (CAM) as an adaptation for arid conditions. CO entering the stomata during the night is converted into organic acids, which release CO for the Calvin Cycle during the day, when the stomata are closed. CAM plants often show xerophytic features, such as thick, reduced leaves with a low surface-area-to-volume ratio, thick cuticle, and stomata sunken into pits.
Green roofs in the northern continental United States rely on sedums which are in the family Crassulaceae. Most varieties of Sedums are not appropriate for humid, subtropical climates and experience root rot and disease problems due to high temperatures and humidity levels. However, two Sedum cultivars, ‘Lemon Coral’ and’ Florida Friendly Gold’ are currently being researched at the University of Florida and appear to be adapting to the humid, subtropical climate of Gainesville, Florida.
Example SCV roof plant palette