Researchers have developed a new formula to allow urban farmers to design their own “light recipe”—a combination of different colors of lighting that could help increase crop yields in vertical farms.

The study, conducted at Grow It York, an indoor urban community farm based in a shipping container at SPARK in the city, developed a mathematical model that could help inform urban farmers of how light varies in different areas of a confined space and how to use this information to design better lighting systems.

The team at the University of York and Vertically Urban (a U.K.-based horticultural lighting manufacturer), looked at how the plants in various parts of a contained farming facility might experience light. Plants near a wall, for example, could experience brighter light because light will bounce more in that area. They then investigated how these differences in light impacted crop growth of kale, radish and sunflower shoots. The study is published in Quantitative Plant Biology.

Fresh fruit and veg

Dr. Daphne Ezer, from the University of York’s Department of Biology, said, “More than 6 billion people will be living in urban centers by 2050, and there is a growing need to ensure that individuals living in these areas have access to fresh fruits and vegetables, especially as climate change threatens crop yields.

“One potential solution is having indoor urban farms that house dense shelves full of crops, also known as vertical farms. The lights in vertical farms can be highly controlled, enabling farmers to precisely design farming conditions to maximize yields.

“However, because of how many lights there are in a vertical farm, energy usage can be high, and many vertical farms do not have the experimental capacity to find the precise combination of lights that would improve their yields while reducing their carbon footprints.”

Highly controlled

The lights in vertical farms can be highly controlled, enabling farmers to precisely design farming conditions to maximize yields, but many vertical farms are small scale, fitted into compact urban spaces, and so taking “time-out” to research different lighting practices to increase yield is not commercially viable.

Will Claydon, the lead researcher of the study, said, “These vertical farms might have a light recipe that is ‘good enough,’ but it would be a risk to try new light treatments, because it could risk their commercial production.

“To tackle this problem, we came up with a creative mathematical modeling strategy, and our key insight through this process is that even in a small vertical farm, there is a lot of variety in light color and intensity in different parts of the farm.

“We were able to see which aspects of light quality are most important for each species of crop, and we hope this new understanding could help pave the way for other vertical farms to optimize the light treatments in their farms, with the benefit of not having to pause production.”

Grow It York

The researchers believe this new “light recipe” model could mean that more vertical farms will be able to increase their yield and energy efficiency, enabling more fresh living greens to be produced in urban centers.

Grow It York, established in 2021, supplies hyper-local produce to the surrounding businesses and locals. The container farm grows salad crops such as pea shoots, watercress, microgreens and herbs, which can also be prepared and eaten fresh at the restaurants within Spark:York.