In 1917 Charles Lathrop Pack established the National War Garden Commission. The idea was to take pressure off of the farmers and growers in America to provide food while we fought, and to help our allies as well. Remember that the mechanized food industry didn’t exist back then the way it does now. People grew and ate their own food. So millions of men fighting meant food that was not planted nor harvested. So Victory Gardens in World War II meant over a billion dollars in food raised and provided by citizens. The food industry itself was threatened and tried to keep a Victory Garden out of the White House grounds. Some of the original Victory Gardens still produce.
Source: Wiki, Military History Podcast