Twenty years ago, the North American green roof industry was in its infancy!
In 1998, I started a nursery in Maryland, the first in North America focused solely on horticulture of green roof plants. Within the next year, Green Roofs for Healthy Cities (GRHC) published its first issue of the Living Architecture Monitor (LAM). Little did I imagine that within the following two decades, I would be involved in over 2000 green roofs, six books, and would be consulting on projects in Europe, China, Morocco, Mexico, Ecuador, New Zealand, and Australia. In that same timespan, GRHC has been instrumental in educating and informing the green roof market and advocating for supportive policy, in the US, Canada and worldwide through the World Green Infrastructure Monitor.
By the late 1990s, Germany had a considerable history of green roofs, so a selection of proven plants for that region of the world already existed. This list was comprised primarily of hardy succulents, most of which were in the genus Sedum. Soon they became the work-horses in the burgeoning North American market, as well. But the multitude of climates within North America made it necessary to investigate new horticultural possibilities.