There are many challenges for plants, shrubs and trees in the urban landscape, but in San Francisco, the biggest challenge is undeniably dogs. There are more dogs than children in this city. Almost every new dwelling built in the city in the last 20 years has been in a multi-family setting, with means there's no backyard for Fluffy to use for her bathroom duties. Instead, the sidewalk outside the building is used. This creates some big problems for the landscape. Here's ho