Backyard vegetables can fight crime, improve health, and boost the economy.

By transforming its vacant lots, backyards and roof-tops into farming plots, the city of Cleveland could meet all of its fresh produce, poultry and honey needs, calculate researchers from Ohio State University. These steps would save up to $155 million annually, boost employment and scale back obesity.

“Post-industrial cities like Cleveland are struggling with more and more unused land, these become sources of crime,” said Parwinder Grewal co-author of a study “Can cities become self-reliant in food?” published J...