Archdaily.com:

In an effort to bring the city closer to its goals for healthy communities and sustainable city planning Philadelphia rolled out a new Zoning Code in 2012 after a four-year process of updates and revisions to the outdated 50 year-old code on the books. The new code now recognizes urban agriculture as a legitimate land use designation. After tackling a few hiccups along the way, namely Bill 120917, that restricted gardening and farming in certain districts, the new code promises to protect and promote urban farming in its various forms whether they are animal husbandry, community gardening or market farming. The code also makes leaps in protecting communities adjacent to farms and making cultivators and farmers responsible for any disturbances to the neighborhood.

Around 40,000 lots are doing nothing in Philadelphia, 30,000 of these lots are privately owned, and 353 lots are being used as urban farms and community gardens. The hope is that the new code will dramatically increase the number of farms and gardens in the city. What's nearly impossible to get around is this fact: Substantial social and urban change almost never happens without muscular state or government intervention.