How many of Seattle’s residents could live off food grown in their city?

If abundant P-Patches and backyard gardens teeming with kale come to mind, you’re like many residents who assume urban agriculture in Seattle could support 50, 80, or even 100 percent of the people who live in the city.

It turns out that the actual number is drastically lower. A new University of Washington study finds that urban crops in Seattle could only feed between 1 and 4 percent of the city’s population, even if all viable backyard and public green spaces were converted to growing produce. The study, published this month in the journal of Urban Forestry & Urban Greening, draws on Seattle’s current land use, light availability, and national nutritional guidelines to determine the city’s carrying capacity for feeding its population.

The results show that it would require a 58-mile expansion around the city to meet 100 percent of Seattle’s food needs.

“We really need a regional solution to food sustainability in the Seattle area,” said lead author Jeff Richardson, a postdoctoral researcher in the UW’s School of Environmental and Forest Sciences. “It’s not going to come from Seattle and it’s not even going to come from King County. We’re going to need the entire region and all these food-producing areas to help achieve food security.”