Green roofs grow in almost every climate on earth. While a green roof is a universal concept, green roofs are most beneficial when they are planted with flora that have a long history in the region. After all, it is the native vegetation that the native fauna is in search of to feed, rest, breed, and nest. For these reasons, it makes a lot of ecological sense to make use of the regional vegetation on green roofs. However, what if the native vegetation is dominated by a suite of low-growing shrubs associated with steppe and scrubland habitats, such as those found in semi-arid climates? In temperate climates, a typical extensive green roof has shallow substrates (7.6-12.7 c, 3-5). However, in hot and dry regions, the viable depth of substrates for green roofs is typically deeper (15-30 cm; 6-12) to match the depth of the root systems of native plants (Dvorak and Skabelund 2021). In North America, the coastal regions of central and southern California, the valley basins of the Desert Southwest and the Intermountain semi-arid basins, and the steppes of the Great Plains are all such places. These are vast landscapes with an abundance of natural habitats known as a scrub, which can include plants such as sagebrush, rabbitbrush, bunch grasses, annuals, geophytes (bulbs, corms, tubers, etc.), and low-growing succulents. Although some of these plants may appear wild in their form and texture, with a little bit of innovation and intuition, some of these hardy and wild shrubby plants have been made to flourish on green roofs. In this article, shrubs and low-growing woody plants are explored for their innovative use on green roofs.
