The grass roots permaculture movement has been hugely influential in the renaissance of urban agriculture throughout the world.
The idea of supplemental food production beyond rural farming operations and distant imports is not new and has been used at times when food shortage issues arose. As early as 1893, citizens of a depression-struck Detroit were asked to use any vacant lots to grow vegetables. These vegetable gardens were intended to produce income, food supply, and even boost independence.
During the First World War American citizens were called upon to utilize any available open space for food growth, seeing this as a way to pull them out of a potentially damaging situation caused by the hardship of war. By 1919, over 5 million plots were growing food resulting in a harvest of more than 500 million pounds of produce. To raise spirits socially as well as to boost economic growth during the Great Depression a very similar practice came into use in order to provide a purpose, a job, and food to those who would otherwise be without anything. The subsistence gardens of the Depression produced nearly 3 million dollars worth of food.
The National Victory Garden Program established during the Second World War set out to systematically establish functioning agriculture within cities. Upwards of 5.5 million Americans took part in the movement which accounted for 44% of U.S. grown produce during the war.