The Maryland Department of Agriculture has regulations dealing with nurseries and the growing and shipping of plants.
The state identifies five types of nursery operations for which certificates and fees are required: Christmas tree farms, greenhouse plant production, landscape nursery operation, nursery stock production, and public agency nursery. The nurseries are subject to inspection for infected stock.
Nurseries are assigned a permanent certification number; nursery inspection certificates are renewed annually. Nurseries that ship interstate and out of state follow a protocol set by the state. There are civil and criminal penalties for not following the regulations.
Green Roofs for Healthy Cities is the Toronto-headquartered trade association for the North American green-roof industry. The association offers training courses, conferences, quarterly magazines, and, on its website (www.greenroofs.org), a GreenSave Calculator that compares the cost of green roofing with conventional roofing systems.
It also conducts surveys of the North American green-roof industry. Among the findings for its most current, the 2011 survey, are:
• In 2010, the industry grew 28.5 percent, up from 16 percent in 2009.
• In 2010, there were 700 projects, up from 433 in 2009.
• Of the 700 projects, 294 were private and 279 public (the rest were unreported).
• Of the 10 top American cities by square footage installed in 2010, No. 1 was Chicago; No. 2 was Washington, DC. Baltimore ranked 7th.
According to Dr. Steve Cohan, a professor in the plant science and landscape architecture department and coordinator of the Green Roof Research Team at the University of Maryland College Park, there is no certification required to install green roofs, and standards have not yet been established.
The Green Roof Research Team is one of a handful of scientific centers in the country studying the subject. Another in Maryland is the Wye Research & Education Center in Queenstown.