Nick Flaherty finds out more about the amazing robotics research and agri-tech development aiding farming and food production in Bristol

For several years there has been a rather scary sign at the entrance to Stokes Croft. This is a countdown for how many harvests we have left before the soil collapses, and it’s not that many years. Technologists in Bristol have been working to address that challenge in a number of ways, from vertical, indoor farming to more efficient farming techniques. Humanity must increase food production by 70% to feed nearly 10 billion people by 2050, and that has to be achieved with 25% less farmland, degraded soils and in an ever more unstable climate. So existing methods of agriculture will not be enough to feed ourselves, as the Stokes Croft sign points out.

LettUs Grow plant physiologist Billy using Ostara


LettUs Grow is an award-winning start-up in Bristol developing technology for aeroponics, or growing crops without soil in large vertical racks. The crops, from herbs and strawberries to even small trees, are grown under LED lights with all the nutrients provided by a mist of water and the plants grow in a ‘soil’ of coconut husk and hemp. This is much more efficient in the use of water and energy, as the light can be tuned to the needs of the particular plants.

“Aeroponics uses 95% less water than farming as it’s a closed loop system where everything is filtered and re-used,” said Ben Crowther, co-founder and chief technology officer. “We use more power but the benefit is that you can position production right by the point of consumption or distribution.”

Harvesting aeroponically grown basil

The company has teamed up with renewable energy supplier Octopus Energy to provide the electricity at night to grow the crops when there is spare capacity, for example from wind turbines. “We use specialist horticultural lighting that is tuned for different types of crops, generally on red and blue with differing levels of green and white,” he said. “You can definitely increase yields for all crops. For things like strawberries, a mix of light and temperature will make very particular things occur – for example, you provide cold shock to strawberries which makes them better for transport, and different frequencies of lighting to make them flower. We work with a world-leading researcher on circadian rhythms for plants at the University of Bristol on how we can apply this to our misting technology.”


The company has been part of a start-up incubator run by the John Lewis department store. One of the ideas they are looking at is to have the vertical farms at its distribution centres or even as part of the department stores, providing food directly to the shop floor.

“The John Lewis deal is an interesting opportunity for future collaboration,” he said. “It’s a really exciting opportunity to work with a well-known UK brand to do exciting stuff. That could be in a number of areas, whether its in-store or otherwise. Vertical farming can provide a very stable rate of supply, really reliably for a low carbon cost.

India checking plant root growth

“We don’t think it should replace hectares of fields,” he added. “Indoor farming, greenhouse and open field farming each have their different roles. If you can grow it in a field, then grow it in a field – it makes much more sense. But in many places it’s just not possible as it uses too much water, pesticides, or the soil is degrading quite rapidly.”

That is a challenge being addressed by another start-up using Bristol technology. “The costs of farming have gone up massively – maybe 85% or so over the last 20 to 25 years, but crop yields and the money coming out of farms have stayed largely the same,” said Ben Scott-Robinson, CEO of Small Robot. It has been working with the Bristol Robotics Lab at Frenchay on a series of robots that can be used to make farming more efficient.

“Farmers can’t afford to take risks, so we developed Farming-as-a-Service as a way to tackle their concerns and help them adopt robotics,” said Scott-Robinson. With Farming-as-a-Service, instead of buying a robot, the farmer simply pays for the delivery of a healthy crop for a fixed amount per hectare. This moves farmers away from paying for costly machinery and offers instead a service based on the operating costs.

Farmers can’t afford to take risks, so Small Robot developed farming-as-a-service as a way to tackle their concerns, and their prototype robots, Tom, Dick and Harrick (pictured) perform different functions to make farming more efficient


The prototype robots, called Tom, Dick and Harrick, all perform different functions. The smallest robot, Tom, sits on the farm in a solar powered ‘kennel’, and regularly races around the field measuring the state of the soil and the crops. It sends all this data back to the internet when it gets back to the kennel, and can call out its larger siblings to come and plant, water or harvest crops.

These larger robots – Dick and Harrick – are based around a novel chassis that is designed to fold up to fit into a van so they can be easily shipped to the farm but are still much lighter than a 30 tonne tractor. They drive themselves around a field using a module that squashes the weeds into the ground instead of using weed killer. The team is also looking at using a laser close to the ground to burn through the stem of a weed. One advantage of regular collection of data by Tom is that the intervention can happen when a weed is small enough to be blasted by the laser.

For fertilising and watering, the boom on Harrick has a precision nozzle that can direct a controlled amount of liquid fertiliser onto the crop. To do this, the module needs to know how high up the plant to spray, and this depends on the condition of the plant, so there is a lot of image processing and computer analysis need. This dramatically reduces the amount of fertiliser required for a field and also reduces the amount of water that needs to be carried across the field. When finished, the robots can be packed up into the van until Tom decides they are needed again, saving the farmer hassle, time and money with this ‘farming as a service’ that will roll out in 2021.

The challenges of producing food efficiently with minimal resources for millions of people are significant, and the continuing innovation and technology development in this city is helping to solve those challenges. Quite a thing to be proud of.

Aeroponics images by Jack Wiseall