The correct answer is : 100%
The amount of food grown in back gardens and allotments is a minuscule fraction of what’s needed to feed us all.
Birmingham has poor soils and no natural significant water supply, and thus never an area where agriculture thrived, it is arguably home to the first urban allotment in the world, the Guinea Gardens. One of these, behind the Botanical Gardens in Edgbaston, is still a thriving allotment.
an aside: The reason why Birmingham is such a green city is mainly down to two factors: First, its location a combined with poor agricultural conditions is within the northern fringes of the ancient Forest of Arden, which has never been cut down for farming.
Secondly, several influential philanthropic industrialists built housing for their workers, and provided them with gardens and/or access to allotments so they could have a healthy diet, and no doubt work better.
Examples include Bournville and the Moor Pool estate. Indeed, the City Council in the mid-20th century paid attention to their estates being near to parks, of which the city has over 600.
A challenge, though, to growing food on former industrial land is the existence of polluted soils, as well as today’s air pollution challenges.
a) See Part Two (What it takes to feed the city) and Part Three (The value of urban agriculture) in the Birmingham 2050 Scenarios Report: https://www.birminghamfoodcouncil.org/wp-content/uploads/2018/04/The-Birmingham-2050-Scenarios-Report_June-2013_lowres.pdf
b) See also this blogpost: heavy metal contamination in Birmingham soils https://www.birminghamfoodcouncil.org/2019/06/08/heavy-metal-contamination-in-birmingham-soils/
c) And this one: Why talk of grow-your-own (GYO) is irrelevant and unhelpful. https://