FILE - A gardener works in a show garden 'RBC Blue Water Roof Garden', designed by Nigel Dunnett and The Landscape Agency, during the Chelsea Flower Show in London on Monday, May 20, 20

 

              FILE - A gardener works in a show garden
FILE - A gardener works in a show garden 'RBC Blue Water Roof Garden', designed by Nigel Dunnett and The Landscape Agency, during the Chelsea Flower Show in London on Monday, May 20, 2013. Environmentally conscious Londoners have made plans to battle some of the predicted effects of global warming by promoting better water management, expanding the city's Victorian sewage network, and “urban greening” - the process of planting trees and rooftop gardens to help managing the heat island effect common to urban areas. (AP Photo/Sang Tan, File)