The Chicago Botanic Garden has planted a 20,000 square-foot vegetable and herb garden, the largest in the Midwest, at McCormick Place West. In the years since, green roofs have gotten a lot of attention, and Chicago has been recognized as one of the leaders in North America. The city has more than 5.5 million square feet on more than 500 rooftops. But even that is still a small number. Those 500 green roofs represent a little less than one-tenth of 1 percent of Chicago’s more than half a million buildings. In Germany, experts said in 2010 that 15 to 20 percent of the flat roofs in the country were green. Washington officials said the city has 2.3 million square feet of green roofs. Philadelphia reported more than 1 million square feet.