We’re in the running to win €500k in international sustainable entrepreneurship competition

We’re in the running to win €500k in international sustainable entrepreneurship competition

It has been all celebrations at LettUs Grow HQ the past week. We’re thrilled to announce we’re one of 25 organisations to have made it to the first stage of the Postcode Lottery Green Challenge. The top prize is €500,000 to further develop the winner’s product or service and bring it to market. The runner-up receives €200,000 and three other finalists will win €100,000 each.

It is amazing to see our team recognised for the fruits of their labour after months of hard work in the LettUs Grow lab. Winning the green challenge would unlock so many doors and enable us to bring our innovative agricultural technology to a global audience much faster than is currently possible.

The international competition, organised by the Dutch Postcode Lottery to provide a helping hand to entrepreneurs starting sustainable businesses, saw applications from 100 countries from all over the world. 

The diverse group of startups that have made it into the top 25 include plans to stop plastic reaching the sea, to make the storage of renewable energy more efficient, and to combat water scarcity around the world. They show the broad range of ways businesses can make a positive impact on the planet, while also being successful.

We are honoured to be included in such an inspiring group of companies from all over the world, every one striving for a better future for our planet. LettUs Grow is entering an exciting time of development, with a talented team all working to help feed the next generation as sustainably as possible.

Now, all we can do is wait. The five finalists will be announced in mid-August, and will then present their pitches to a jury on 13 September in Amsterdam, where the winner will be announced.

Keep your fingers crossed. We will!

December update: Growing fast!

And breathe. After a really busy month here at LettUs Grow HQ, we are all finally getting the chance to sit back and reflect upon some fantastic achievements, alongside building looking forward to an exciting 2018. Read on for the month in review! 


Let's start with the reason we're all here, helping farmers grow tasty food! December has proved the culmination of a great deal of work by our engineers, resulting in the deployment of our aeroponic hardware into our local vertical farm, Grow Bristol. 

This means that the baton has now been passed to our "growing team" of biologists and environmental scientists to demonstrate the how rapidly this hardware can grow tasty leafy greens, strawberries, and much more, over the new year.  

Results thus far have been clear, with the LettUs Grow aeroponic pea shoots reaching same size (and biomass) as the hydroponic pea shoots - in half the time. 

This particular comparison was made through a experiment specifically set up to compare yield between hydroponic and aeroponic systems, and as such, both sets of peas were grown using the same lighting, environment, water, and nutrient dosing procedure.

We're excited to continue to produce and publish these results over 2018, hopefully sharing the benefits of aeroponics with the widest possible audience.

Partnerships, Investment & Events

As alluded to above, we are very proud to have established a really strong R&D focused partnership with Grow Bristol, our local vertical farm. This has resulted in broad deployment of both our aeroponic hardware and farm management software. All of which is focused on improving productivity and crop quality, whilst rendering the farm simpler to operate. 

Alongside growing plants, the management team has also been focused on growing the business! As a result, it was fantastic to complete the 3-month Bethnal Green Ventures program of advice and investment with a pitch at our demo-day on the 29th of November. We have been immensely proud to work for 3 months alongside some brilliant other startups focused on delivering social and environmental impact, and are excited to continue to work with such closely aligned social investors as we move towards our seed round of investment in Q1 2018.

Our aeroponic greens on show in Borough Market, London Food tech week.

Our aeroponic greens on show in Borough Market, London Food tech week.

This followed on from our showcase in Borough Market through the brilliant London Food Tech Week and participation in the IoT Boost national showcase, both of which resulted in an exciting end to November!

The good news continued through the rest of December, as we were very pleased to be selected to pitch at the national SETsquared investment showcase in London, before also winning funding and consultancy from the University of Bristol enterprise competition.

Festive Reflection

None of this could have happened without the continued, brilliant hard work of the whole team. The fact that this progress was delivered over just one month is very impressive, and a Christmas break very well deserved! 

However, this is really just the beginning, with an expanded team, more test space, and some exciting new partnerships moving quickly down our pipeline for Q1 next year. So make sure you also keep an eye out for the next blog post, where we will look forward to a very exciting 2018.

But for now we'll take a break, and sign off by wishing you a Merry Cress-mas and Hap-pea New Year!!

The biological basis for aeroponics

The biological basis for aeroponics

The following constitutes a general explanation of the basis of aeroponics, alongside a comparison of its benefits versus hydroponics. We are always happy to discuss this topic in further depth if you'd like so please get in touch. 

The fundamental justification for yield improvements in aeroponic systems, versus hydroponic alternatives, is the superior access that roots have to oxygen. At any one time, the optimal amount of irrigation can be derived from balancing the plant’s requirement for sufficient nutrients (of a given type), water, and gaseous exchange to meet biochemical requirements within the plant root cells.

Source: Horizon, EU Research & Innovation Magazine

Source: Horizon, EU Research & Innovation Magazine

Hydroponic systems immerse plant roots in a nutrient rich solution of water, which is either maintained as a narrow film or flooded and drained to expose the plant roots intermittently, to air and then water. In such systems, the roots can use only the oxygen dissolved in nutrient solution, the concentration of which is very low due to its low solubility, roughly 8mg/l at room temperature. This restriction is exacerbated by higher temperatures, which increase the respiratory demand for oxygen by the roots (approximately doubling for each 10C rise in temperature, up to about 30C), and crop demand, which is higher when the photosynthetic activity increases. A decrease below 3 or 4 mg/l of dissolved oxygen, dramatically inhibits root growth and causes a visual change in root appearance, to a brown colour, which can be considered the first symptom of oxygen deficiency.

As previously communicated, in an aeroponic system, the delivery of nutrients and water is a function of the duration, manipulation, and intensity of irrigation. To a point, increasing supply of these resources increases growth rate. However, the effect of gaseous exchange upon growth rate acts in opposition, with increased irrigation waterlogging the root bed and generating hypoxic conditions, where roots cannot access sufficient oxygen for aerobic respiration. The effect of this stressor has been examined in natural waterlogged conditions and shown to stimulate anaerobic respiration in plant roots, resulting in the creation of fermentation products - ethanol, alanine, and lactate. Aside from accumulation of these potentially toxic by-products, the growth of the plant is limited fundamentally by this reliance on anaerobic respiration, which is up to 15 times less efficient than the aerobic equivalent (Smith et al, 2010).

Experimental validation of the impact of this process upon yield has been observed by Yin et al (2009) where two cultivars of Chrysanthemum plants were waterlogged and growth compared to that of plants in naturally aerated soil. Accumulation of toxic by-products, reduced energy conversion from anaerobic processes, and increased exposure to Reactive Oxidative Species (ROS) generated in waterlogged tissues, contributed to increased rates of senescence in the waterlogged plants. In summary:

“Hypoxia is the primary stress factor under waterlogging (Shiono et al., 2008). When tissues are hypoxic, the aerobic energy generating system sharply decline and the functional relationship between roots and shoots is disturbed (reviewed in Vartapetian and Jackson, 1997). In most cases, oxygen deprivation affects directly the roots and indirectly the shoots.”

The roots of plants grown within hydroponics exist in a constant state of oxygen deprivation, which has been shown to have significant impact on plant health, growth rate, and therefore yield.

Conventional High Pressure Aeroponic (HPA) systems address this issue by growing roots in a gaseous environment supplied by nutrient dense mist, an improvement, but have little control over mist behaviour and subsequent deposition onto root. Similarly, this lack of control does not allow the farmer to adjust nutrient deposition throughout the plant's growth, or respond to inconsistencies in growth, which fundamentally will impact on yield - and therefore a farmers bottom line.

HPA systems operate by forcing nutrient rich water through numerous valves embedded in pressurised tubing, with the mist generated then depositing upon the plant roots. This is simple on a small scale, but that pressurised system becomes seriously difficult to scale into a productive vertical farm. Most vertical farmers have sensibly steered clear of this complex solution when operating at scale. 

This presents a significant opportunity for innovation.


Ritter, E. Angulo, B. Riga, P. Herran, C. Relloso, J. San Jose, M. (2001). Comparison of hydroponic and aeroponic cultivation systems for the production of potato minitubers. Potato Research.

Hosseinzadeh, S. and Verheust, Y. and Bonarrigo, G. and Van Hulle, S. (2017). Closed hydroponic systems: operational parameters, root exudates occurrence and related water treatment. Rev Environ Sci Biotechnology.

Smith, A. and Coupland, G. and Dolan, L. and Harberd, N. and Jones, J. and Martin, C. and Sablowski, R. and Amey, A. (2010). Plant Biology, Garland Science.

Dongmei Yin. and Sumei Chen. and Fadi Chen. and Zhiyong Guan. and Weimin Fang. (2009). Morphological and physiological responses of two chrysanthemum cultivars differing in their tolerance to waterlogging. Environmental and Experimental Botany.


Venturefest Bristol & Bath 2017

It was fantastic to be involved at Venturefest Bristol & Bath last Tuesday, where we pitched at the Silicon Gorge investor event and showed off our demonstrator to the public.

We really enjoyed explaining more about the potential of vertical farming to transform urban agriculture (particularly aeroponics) to a wide range of people - and are glad they got as excited as us!

It was also great to have our partners Grow Bristol along on the day to show off their delicious produce and explain more about their Bristol-based vertical farm. 

Luckily, this is not the last event we'll be at with LettUs Grow, as next Thursday we'll have a stall in Borough Market as part of the London Food-Tech week's takeover. If you're in the area make sure to drop on by - or if not, sign up below for more updates in the future!  

SSE Graduation & Grow Bristol partnership

SSE Graduation & Grow Bristol partnership

The super tasty Grow Bristol microgreen salad.

The super tasty Grow Bristol microgreen salad.

Ben, LettUs Grow, meets Marvin Rees, Mayor of Bristol.

Ben, LettUs Grow, meets Marvin Rees, Mayor of Bristol.

It was brilliant watching our Engineering Lead, Ben Crowther, graduate today from his year-long programme with the School for Social Entrepreneurs (SSE) in Bristol City Hall. It's been a fantastic course that's really helped us progress over the past year to where we are today. 

Real pleasure for us all to meet Marvin Rees, Mayor of Bristol, as well, and we look forward to working with the Council on building Europes first aeroponic farm in Bristol during 2018.

We were also really excited to officially announce our partnership with Grow BristolGrow Bristol CIC are a vertical farming enterprise that is conducting a new kind of market gardening in city spaces not normally suited to agriculture. 

LettUs Grow™ have partnered with Grow Bristol to help them scale up their farm, without scaling up the inefficiencies of their existing technology.

We're really excited to work closely together going forward. Look out for a more detailed blog post soon.

Pitching at Silicon Gorge, Venturefest Bristol & Bath.

The Silicon Gorge selection event.

The Silicon Gorge selection event.

After a few months hard at work in the lab, we're very excited to be one of only 10 startups selected to pitch in the Silicon Gorge investor showcase at VentureFest Bristol & Bath.

We're really excited to be showcasing our patent-pending efficient irrigation and control technology for vertical farms to investors and public alike.

We'll also have a tech demonstrator running all day, so make sure you register for a ticket, come have a chat, and find out more!

For the full story, check out this great TechSpark article.