Nairobi, the bustling economic center of East Africa, faces rapid urbanization like many other African cities. The ongoing expansion of urban areas, especially informal settlements, poses a severe challenge to food security for its about 3,7 million inhabitants. One estimate suggests that about 38 percent of the city's population suffer from chronic food insecurity. In order to deal with those difficulties, governmental institutions as well as other NGOs try to find innovative ways of growing food in areas where space is usually very limited. Vertical gardens, also known as sack gardens, are one possible solution.