Inside the underground hydroponics farm in London

Q: How did you get the idea for the business? 

RB: I used to import teak garden furniture from South-East Asia, and became interested in sustainability in the late 1990s. When I moved to London and met an old friend, LEDs were just coming on to the market, hydroponics had been around for a long time, and there was redundant urban space, so we brought these together. Neither of us had a farming background, so we joined forces with Chris Nelson who had 35 years' experience of growing hydroponics.

Q: How is the project different to traditional farming? And to other indoor farms?

RB: We dont use any pesticides, we recirculate water, and we are less than a mile from New Covent Garden Market, which distributes food around the country. We are effectively giving customers a longer shelf life and reducing food waste.

Indoor farming is all about saving space and growing more with a smaller footprint. The long thin structure of the tunnel works well for us: we can keep an eye on the products, which are only stacked four high, without any machinery to lift us up to inspect.

We currently grow leafy greens, baby leaves and micro greens using entirely artificial light. It is not yet profitable enough to grow heads of lettuce, soft fruit or peppers in the UK.

LEDs produce heat and light so we can maintain the tunnel at 23–25°C year-round, the ideal temperature for the crop, without heating it. We use dehumidifiers too, to control the environment perfectly. Grown above ground pea shoots would have three to four harvests per year, and in a greenhouse 25–30 – but we get 60.

Q: Are the premises bought or leased?

RB: We lease the space from Transport for London very cheaply. It works out as about £10/m², and we are exempt from business rates.

Q: What about your carbon footprint?

RB: We are working towards being carbon-neutral. We use redundant urban space, we don't use any pesticides, we grow close to the point of consumption and we use less water, so we are compiling all that information to work out our carbon footprint.

Q: What is the optimum scale of the business?

RB: At the moment we have 6,038m² and 500m of growing space, and we plan to expand into the rest of the tunnel. We are also looking at other sites to scale up.

Q: How is the business funded?

RB: We initially crowdfunded £650,000 and with several subsequent rounds of investment have raised £2.3m. We are still looking to finance the next phase of 2,000m² which is the scale where it should really start to be profitable.

Q: What are the next steps for the business?

RB: We've worked with the University of Cambridge's Department of Engineering since we started, which has been monitoring the temperature, humidity, air flow and carbon dioxide, and we are developing a model that will help us understand the environment before we build future sites.

We will be able to predict the optimum thickness of the walls, radiant heat and convection heat as well as the balance of all these factors. From this we will create a transfer model, so for a given building and equipment we could work out how many LEDs we would need and get an accurate idea of how we should operate there, whether its another tunnel or a warehouse.

Data is key: we already have the perfect environmental recipe for growing, say, coriander, and the composition of light, how much from the red spectrum and how much from the blue, to create the perfect crop.

Richard Ballard is co-founder of Growing Underground  richard@growing-underground.com

Related competencies include: Agriculture, Sustainability