Understood, but I suspect some of that may be cultural (allotment gardens in the UK are extremely popular with lengthy waiting lists), and synchronised with the

Understood, but I suspect some of that may be cultural (allotment gardens in the UK are extremely popular with lengthy waiting lists), and synchronised with the push in the USA during the 1940's and 1950's towards suburbanisation and consumerism. My gut feel is that because there was already a popular trend to 'getting your fingers in the soil', as well as the slow food movement, that combined with the forced rethink of how we spend time, effort, and money, we will see some longer lasting effects.