I was thinking about the garden project, Meet Molly (a children's book), and WWII when it occurred to me that history does sort of repeat itself. Sort of. There are a great deal of things that are vastly different now than they were in the 1940's, but maybe the American psyche has a providential gardening gene that "kicks in" during hard times.
Sure, it might just be economic (less income + higher prices = move towards gardening), but I think this is more about needing to feel human again. Dirt on your hands, wind in your hair human.