Vertical farming envisions a future in which our food is grown in urban pockets and beneath our feet. But just how far can it go?
The Pasona Urban Farm, which opened in the nine-story office of a Japanese recruitment firm in 2010, promised a future in which food would be grown within feet of the people who would eat it.
Tomatoes hung from meeting-room light fixtures, a rice paddy filled a large conference space, and mushrooms grew in drawers concealed beneath benches. The office looked more like a farming museum than a place of business.
While the modern concept of vertical farming – growing food in trays or pipes stacked on top of one another like a giant plant lasagna – dates from the 1990s, farmers have long sought ways to grow more in less space and with less soil. Step- Fruit trees are grown as low as 1ft (30cm) off the ground and spread laterally to fill thin strips of space in allotments and orchards. The step-over technique is based on espalier training, which may have originated with Ancient Roman grape cultivation.
If we did find a way to overcome the problems of cost and energy use, what would a world where all our food is grown in such farms look like?
However, vertical farming in the modern sense is rapidly spreading. Oishii, a vertically farmed strawberry brand based in New Jersey, is one example. A punnet of its coveted Japanese Omakase strawberries cost $50 (£44) in a high-end New York supermarket in 2021. For some, this was proof that, with time, vertical farming could compete with, and eventually surpass, traditional farming in terms of quality. For others, the exorbitant price highlighted the enormous challenge of commercialising vertical farms.
While the technology shows great promise, the costs in terms of both money and energy remain high. This includes leafy salads, smaller vegetables and fruits like tomatoes and strawberries, as well as high-value crops that grow quickly. are about the limit of what is currently commercially available from vertical farms.
But what is the exact limit of what we can grow in a vertical farm? And, if we could solve the cost and energy issues, what would the world look like if all of our food was grown in such farms? Could we ever farm without using any soil?
Farming upwards
A vertical farm has no strict definition, but they typically consist of shallow trays stacked within a building and lit with LED lighting at each level. Many vertical farms have no windows and are even constructed underground.
These farms must provide everything, including water, nutrients, sunlight, and possibly pollinators and pest control. Others could be built in massive greenhouses, taking advantage of the Sun’s light and heat while still controlling other inputs such as water.
While soil is sometimes used, increasingly vertical farms use hydroponic or aeroponic systems in which nutrient-infused water (for hydroponics) or water vapour (for aeroponics) is circulated directly around the plant’s roots. “The water and nutrient efficiency is really quite high in hydroponics and aeroponics because the roots can get those nutrients and water in a lot quicker,” says Laura Vickers, a plant biologist and the head of the Urban Farming Group at Harper Adams University in the United Kingdom. “There is no organic matter, nothing for the plant to compete with or extract water from.”
This means that using vertical farms can significantly reduce the amount of water and fertiliser required to grow food. Meanwhile, the closed-off, controlled environment of vertical farms can help to keep pests out, potentially lowering the need for pesticides.
Crops may also be able to grow in areas where conventional farming is not possible. Astronauts on the International Space Station, for example, are growing their own food in soilless systems under LED lights, with crops including cabbage, mizuna mustard, lettuce, and kale.
However, because vertical farms require little land, food can be grown close to cities, according to Natalia Falagan, an engineer at Cranfield University in the United Kingdom, which could have significant benefits. Shorter supply chains may improve both food security and food quality, because the faster food reaches us, the less nutrients deteriorate and unseen toxins, such as mycotoxins, develop. It would also result in far fewer food miles than many imported alternatives, helping to ensure crop provenance while also reducing the burden on natural resources such as soil, water, and the atmosphere, she claims. Furthermore, she adds, with advanced plant science, the crops could be engineered to be healthier and tastier.
According to Falagan, having vertical farms in the midst of cities could also help to raise our awareness of how our food is produced. Pasona Urban Farm, for example, wasn’t just for show; the company hoped that allowing office workers to harvest their own food at work would improve both their mental and physical health. According to Falagan, having a stronger connection to where our food comes from may also encourage consumers to be more mindful of food waste. “If people realise how much work goes into producing our food,” she says, “they might think twice about throwing it out.”
Most vertical farms are currently focused on low-biomass crops, such as herbs, salads, and small fruits and vegetables that weigh less per portion. because there is a higher yield for the amount of heat, light, and water required. They also have short life cycles, allowing them to make the best use of available space, according to Vickers. A leafy green grows quickly and can be harvested in days or weeks, whereas a pumpkin takes months to grow and must cure in sunlight.