Business and Impact

What does GrowUp do?

GrowUp Urban Farms is an urban farming startup based in the heart of London. We currently operate a demonstration farm – The GrowUp Box – in Stratford, East London, as part of the RoofEast project. The GrowUp Box is designed from an upcycled shipping container with a greenhouse built on top. You can check out some photos of the GrowUp Box here. We grow fish and a range of salads and herbs in the Box which we sell to local restaurants.

Why did you start the business?

GrowUp Urban Farms grows sustainable food for a local market. We want to change the production and distribution of nutritious food which is consumed in cities. We aim to reduce the environmental impact of agriculture and employ local people so cities can be more self-sustaining – something that will become increasingly important as our climate changes and our cities expand.

We built the GrowUp Box to demonstrate urban aquaponics and act as a prototype for future farms and systems.

Where do you sell your produce?

We sell our produce to restaurants and retailers in the local area. Hear what some of the chefs we’ve worked with have to say about us. By delivering locally, we are able to ensure freshness and keep our carbon footprint low.

What impact can GrowUp have on a local community?

The environmental benefits of our farms include reducing waste products from agricultural production and making use of previously unused urban brownfield sites. We can reduce the environmental impact and cost of transportation and packaging by selling and delivering to local customers.

Urban farming gives communities a chance to make informed decisions about the way their food is grown. Our food is fresher (as we deliver locally), grown more sustainably, doesn’t use harmful fertilizers or chemicals and is more consistently priced regardless of the season.

We are building expertise in aquaponic urban farming and raising awareness about the way food is grown for people living in cities. Through the GrowUp Box, we have already reached a wide range of audiences, including schoolchildren and hobby aquaponicists. We also hold events for specialist groups such as universities and community groups.

Our aspiration is to employ and train local young people who may have dropped out of formal education or been unable to find employment, and provide them with the skills, experience and confidence to work in urban farming or develop transferable skills to help them move into the area they want to work in. The more farms we build, the more people we can employ, and the more communities in which we can have a positive impact.

Why do you want to grow food in cities?

The simple answer is that cities are where the people are. By 2050, more than 6 out of every 10 people on the planet will be living in cities. Here in the UK 82% of the population already lives in urban areas, and this figure is expected to rise even further in the future. By reducing the distance from farm to fridge we reduce the amount of greenhouse gases associated with the processes of refrigerating, storing and transporting food.

The way food is grown now is unsustainable. With a growing population, innovation in agriculture is needed if we are to develop a socially and environmentally sustainable means of feeding people in cities. Traditional agriculture currently accounts for over 30% of Greenhouse Gas emissions, 70% of freshwater use, almost 50% of all available land on earth.

GrowUp Urban Farms aims to address some of the fundamental flaws in our global agricultural system by using aquaponic and vertical growing techniques to build farms in cities. By using empty rooftop and brownfield sites in inner-city spaces, our farms help make use of neglected city spaces in a way that adds value to these spaces and the people involved with them. Large cities such as London also tend to be on average 4° warmer than the surrounding countryside due to the ‘urban heat island’ effect, which lowers heating costs and makes it particularly suitable for growing produce.

All our produce is sustainably grown and delivered locally – reconnecting people with the way food is produced and what it takes to produce it. This reconnection can help people to make an informed choice about the food they eat. With growing awareness and demand for ethically produced food, GrowUp is well-positioned to become an innovator in food production that is well-adapted to an urban environment. 

Why have you started in London?

London is the city that the rest of the world looks to when it comes to innovation and sustainability – and offers exciting opportunities for us to scale the business and build more farms. London has plenty of potential for urban food development. The sustainable restaurant network in London is active and competitive when it comes to sourcing niche and exciting local produce. The city is also creating a growing awareness and demand for ethically produced food.

How did you use the money you raised on Kickstarter?

Our Kickstarter campaign took off in late February, 2013 with a goal of raising £15,000 to build The Box. By the end of March, we had surpassed that goal with the help of our 300 backers. We used the money we raised through crowdfunding to buy the materials needed to build the GrowUp Box. We felt that it was important for us to show our dedication to the project by covering the design and build labour costs ourselves – after all, we were asking people to give us their money, so it was only fair that we contribute too.

If you’re thinking about running your own crowdfunding campaign, there is lots of information on Kickstarter about how to plan your campaign.

Are you currently hiring or taking on any new volunteers?

We’re chuffed that you find what we do so inspiring and interesting. Our aspiration is to employ local young people who may have dropped out of formal education or been unable to find employment, and provide them with the skills, experience and confidence to work in urban farming or develop transferable skills to help them move into the area they want to work in. The more farms we build, the more people we can employ, and the more communities in which we can have a positive impact. Kindly check our volunteering and job opportunities pages regularly as any future opportunities will be posted here first.

If you share our passion for changing the way we feed people in cities, we may be able to offer you the chance to come and volunteer with us at the GrowUp Box. We appreciate that this isn’t the same as a job offer, and in keeping with our employment values we want to be clear that volunteering will not lead to a job at GrowUp Urban Farms. We won’t be offended if it isn’t something you’re interested in, but if you’d like to find out more about volunteering with us, please let us know so we can arrange for you to visit the Box and have a chat in person.

Are you interested in collaborating outside of the UK?
Currently, we are a very small team focused on developing our business in the UK and are not looking to expand abroad at the moment.

There are several other organisations that might be of interest to you (including BrightAgrotech  and The Urban Farming Guys and we can also recommend looking at the research that has been done at the University of the Virgin Islands into building low-cost aquaponics systems in tropical climates.


What is Aquaponics?

Aquaponics is the name of the technique we use to grow our salads, herbs and fish. It combines aquaculture (fish farming) and hydroponics (growing in a nutrient solution without soil) in a recirculating system where water is cycled from fish tanks through plants and back into the fish tanks. The plants absorb the waste nutrients in the water, and in turn, filter the water for the fish.

Indoor Aquaponics Explained

I love what you’re doing — how can I find out more about setting up my own aquaponics system?

We know lots of you are really interested in finding out more about aquaponics. If you’re in London or in the UK, you can check for the next open day at the GrowUp Box.

You can also contact the British Aquaponics Association (BAQUA) for more information about aquaponics in the UK.

If you’re not local to London and you’d like to find out more about aquaponics then are lots of online resources that you may find useful. We can recommend that you check out the Bight Agrotech website where you’ll find a number of podcasts and tutorials all about aquaponics and setting up your own system.

If you’re interested in setting up your own aquaponics system, we can also recommend reading ‘Aquaponic Gardening’ by Sylvia Bernstein – a great book to get you started with backyard aquaponics.

Is food grown in aquaponics systems organic?

Under current EU regulations, only plants grown in soil can be certified as organic. This means that whilst we grow without any chemical pesticides or fertilizers, our produce can’t currently be certified as organic.

Does your salad taste like fish poo?

No, it tastes great (although we have to admit, we’ve never eaten fish poo). Since the roots of the plants absorb the nutrients from the water, the leaves (the bit we eat) are clean, healthy and don’t sit in the water. Fish poo contains high amounts of ammonia and other nutrients that act as great fertilisers. The solid waste (fish poo) is removed from the system through the filtration system leaving just the nutrients in the water for the plants to feed on.  As the plants take up the nutrients their roots act as filters re-circulating the clean water back into the tank. Animal poo (including human) has been used as a fertiliser in farming since the dawn of time, ours just happens to come from fish.

Are there any issues with diseases in the water?

Fish health is key to the success of an aquaponics system. The main cause of fish disease in aquaponics and aquaculture comes from overcrowded tanks and unclean water. To maintain the health and high welfare of our fish we do the following: 

  • We don’t overcrowd our tank – ensuring our fish have enough space is the first step to controlling disease.
  • We monitor fish behaviour – you can tell a lot about the health of a fish by the way they behave.
  • We check for any odd spots on the fish or in their discharge – these can often be the first signs of disease.
  • We check water quality – making sure the water temperature and pH are at optimum levels is key to maintaining a healthy population of fish.        
  • We source fish fingerlings from CEFAS-certified suppliers only – this minimises the risk of diseases being introduced into the system.
Are Tilapia the best type of fish to use in aquaponics and what else do you grow?

Tilapia are ubiquitously farmed across the world and they are well-trialled in aquaponic farming systems. They’re a hardy fish and prefer to live in larger groups, making them ideal to farm at a slightly higher density than other fresh-water fish. They are also omnivorous, which means they can be fed on high-protein food that isn’t made from fish-meal and fish-oil. Whilst we currently use an industry-standard fish food in the GrowUp Box, we’re exploring options for fish-meal free fish food, a key part to creating a more sustainable food loop for aquaculture.

Tilapia are a warm-water fish, which make them ideal to grow during the summer months, reducing heating costs. And of course, they taste delicious!

How do you make sure the fish are being farmed in an ethical way?

Animal welfare is extremely important to us and we believe it to be key to the success of commercial urban farming. We regulate and monitor a number of conditions on our farms including:

  • The water temperature;
  • The chemical composition of the water;
  • The amount of food we give the fish;
  • Light levels;
  • And oxygen levels;

We also make sure to optimise the stocking density of our tanks so that the fish are healthy and happy – rather than stocking them as densely as possible. Tilapia like to live in large groups. This means that they can live in quite high densities, but we are also careful not to overcrowd the tanks. When it is time to harvest the fish, we make sure this is done humanely.

How do you kill the fish?

We take the welfare of our fish very seriously – and this includes being open and transparent with our supporters and our customers about how we kill the fish.

Currently in the GrowUp Box we kill the fish in the traditional fisherman’s way – we take each fish out of the tank individually and hit it hard just behind the gills to break its spine (this is called percussive stunning). We harvest all the fish in a single session, so as not to cause any undue stress.

Some larger fish have very strong bones, and for this reason we can’t guarantee that a single hard blow would kill them. Furthermore, at a commercial-scale it isn’t practical to use percussive stunning. For this situation we’d have a specially built kit. When the fish are ready for harvesting, they are taken out of the main tank and put into a smaller container. By running an electrical current through the water in this tank we can stun the fish so that they are immediately rendered unconscious. By passing a second, longer current through the water the fish are then killed. This also keeps the stress levels in the fish population lower, which is better for them and makes them taste better.

Can you grow root vegetables using aquaponics?

Technically it is possible to grow vegetables like carrots and potatoes in an aquaponic system – but we choose to grow green leafy salads and herbs for a number of reasons:

  • If you wanted to grow root vegetables you’d probably need to use aeroponics (using a water mist, rather than a nutrient solution to feed the plants) and it would be tricky to get the environmental conditions right to grow those crops successfully;
  • Aquaponics is very well suited to leafy green plants because the waste from the fish is so nitrogen-rich. We want to minimise any additional nutrients we have to add for the plants and make the most of our natural source of fertilizer;
  • Salads and herbs are high-value perishable crops, and it makes sense to grow them as close as possible to the people who are going to eat them.      
How do you know how many fish you need to produce the right amount fertilizer for the plants?

Aquaponics relies on keeping a careful balance of nutrients and chemicals in the water so that both the plants and the fish are healthy. We can calculate how much waste the fish will produce by measuring how much food we give them, and understanding the chemical content of that food. We can then adjust the amount of food we feed the fish so that there are always enough nutrients for the plants.

What do you feed the fish?

We currently feed our fish (both the Tilapia and the Carp) on an industry-standard fish food, which includes fish-meal and fish-oil from wild-caught fish. We think aquaponics has the opportunity to break the unsustainably reliance of aquaculture on wild-caught fish or soya. We’re exploring alternative food sources including algae and insects for Tilapia.

Do plants grow faster in aquaponics than in soil?

Aquaponics is a controlled growing environment — this means we control the amount of water and nutrients that reach our plants, and we have a growing cycle (the length of time it takes to go from seed to harvest) of around 8 weeks (and this varies depending on the type of plant). This is partly because our plants get the nutrients they need directly to their roots, and partly because we’re growing crops that are well suited to the nutrients in fish waste. How fast our plants grow depends on the time of year, the temperature and the amount of sunlight. At a commercial-scale, using LED lighting to supplement natural light we would also be able to grow salads between October and February, when you wouldn’t normally be able to grow salad in the UK. This means that over the course of a year, aquaponics can be much more productive than traditional soil-based farming.

Do you use any chemicals in the system?

We use a small amount of some chemicals to help maintain the pH in the system. Maintaining a stable pH is key to a healthy aquaponic system. Our system is maintained at pH6.2 to pH6.6 which enables the greatest nutrient availability to the salads and is also healthy for the fish. To raise pH up we use Calcium hydroxide (hydrated lime) or Potassium hydroxide (potash). On the odd occasion that we need to reduce pH, we take harvested rainwater (pH neutral) and add it to the system.

The GrowUp Box

What kind of technologies do you use in the GrowUp Box?

The main technology that we use is aquaponics. It combines aquaculture (fish farming) and hydroponics (growing in a nutrient solution without soil) in a recirculating system where water is cycled from fish tanks through plants and back into the fish tanks. The plants absorb the waste nutrients in the water, and in turn, filter the water for the fish.

A key part of the aquaponics cycle is the filtration that converts the waste from the fish into nutrients that can be absorbed by the plants. In the GrowUp Box, we use two stages of mechanical filtration followed by a stage of biofiltration using Kaldnes to create a large surface area where the bacteria can convert ammonia into nitrites and then into nitrates.

By using vertical growing techniques we increase the density at which we can grow crops. This helps us maximise our yield per square metre, a necessity in city centres where the price of land is at a premium. To do this, we use ZipGrow© towers sourced from Bright Agrotech. You can find out more about the ZipGrow© towers on the Bright Agrotech website.

The greenhouse on the GrowUp Box was custom built for us to fit our shipping container. Built by Naturelight, the greenhouse has a patented roof design with up to 90% openable roof area. This is great for natural ventilation in the GrowUp Box, where it isn’t economically viable to build a more expensive ventilation system. We recommend Naturelight Greenhouse Systems in particular for their excellent customer service and reliability.

We grow all our produce from seed. We use our propagation stations to germinate the seedlings, using Rockwool rooting plugs as a growing medium. We custom-designed our propagation systems specifically to maximise the space available to us in the GrowUp Box and we source most of our component parts from Hydrogarden.

Since aquaponics is a living system we can’t use pesticides on our plants as these might enter the water and harm the fish. That means we rely on Integrated Pest Management (IPM) techniques to keep down pest numbers in our greenhouse. IPM uses natural predators of common pests to keep numbers under control and prevent damage to crops.

Can I buy a GrowUp Box?

If you are within the UK and would like a GrowUp Box of you’re own we would love to hear from you, please contact sam@growup.org.uk for more information. We think that the Box is an amazing tool for education and would love to see more sprouting up around the country (excuse the pun).

How did you build The GrowUp Box?

The GrowUp Box was custom-built from an upcycled shipping container with a greenhouse on top. We use ZipGrow© towers from Bright Agrotech in the greenhouse to grow over 400 plants at any one time. The rest of the equipment (fish tank, pumps, etc.) is standard aquaculture and hydroponics equipment, mostly sourced from Hydrogarden.

How do you know when the fish are ready to be harvested?

We harvest fish from the GrowUp Box once in the spring and once in the autumn. Tilapia take around 18 weeks to grow large enough to harvest, and we harvest them when they weigh about 350g – 400g each. Carp grow slower over the winter months when the weather and the water is cooler. 

How do you make aquaponics financially viable?

We receive lots of questions from people asking us to share our costs and outputs from the Box to understand how we’ve made it commercially viable (by which we think people want to know “Can I make a living if I build and farm a GrowUp Box?”).

The GrowUp Box isn’t designed to be a commercially viable farming system. If you were to farm the GrowUp Box at its maximum intensity, it would probably take you about 8 years to get break even on your investment if you only brought in revenue from sales of salads, herbs and fish. For most people that isn’t going to be enough to live off!

There are many more benefits we’ve seen from the GrowUp Box aside from the revenue we generate from selling produce. As with most small-scale urban farming, teaching people about sustainable food production is an important social benefit that we’ve been able to deliver through the GrowUp Box. We’ve hosted events, workshops and lectures at the Box, to share our knowledge and experience of being urban farmers, and to engage the local community in the issues around and the importance of sustainable farming.

We’re a business, and we believe that we can have a positive impact on the planet and make money at the same time. But we also believe that we’ll be able be able to have the most significant social and environmental impact if we can commercially scale our business successfully. For this reason, we’re not currently in a position to share our business model and the details of how we make our business financially viable. 

Can you tell me how to build my own GrowUp Box?

We could tell you but then we’d have to kill you. (Only joking). The GrowUp Box is a prototype and we hope in time to be able to provide both the Box and its design to people anywhere in the world who want to set up their own aquaponic urban farm for their community. Right now, we’re not in a position to do that – we’re a young company and it takes time to bring a product to market. There are no patents on the Box – so if you want to make your own, you don’t need our permission!

Can you help me set up my own aquaponics system outside of the UK?

We are pleased to hear that you have found our model inspiring and you are interested in developing an aquaponics system yourself. We are not selling GrowUp Boxes outside of the UK at the moment.

However there are several organisations online that you might consider researching further, such as Urban Farming Guys and other organisations that currently use aquaponics in tropical climates. The book Aquaponic Gardening by Sylvia Bernstein is a good place to start and provides information when setting up an aquaponic garden and is a good starting point for your other queries regarding the technicalities of aquaponics.

Why not make the GrowUp Box profitable?

The main purpose of the GrowUp Box is as a demonstration farm and was never intended to be a commercially viable farming system. There are many more benefits we’ve seen from the GrowUp Box aside from the revenue we generate from selling produce. As with most small-scale urban farming, teaching people about sustainable food production is an important social benefit that we’ve been able to deliver through the GrowUp Box. We’ve hosted events, workshops and lectures at the Box, to share our knowledge and experience of being urban farmers, and to engage the local community in the issues around and the importance of sustainable farming.

Do you grow the same produce in the Winter and Summer?

This year, during the winter months, we’ve switched over to growing carp in the GrowUp Box. They are happier at a much lower temperature compared to Tilapia, which helps us to cut down on our heating costs over the winter. Have a look at the food wheel below to see what grows best at different times of year.

We produce salad (mostly leafy green plants), herbs and micro-greens all year round in the GrowUp Box. We grow lettuces through the summer, herbs such as basils and parsley through the autumn and oriental greens like rocket, pak choi and green mustard through the winter months.

Seasonal Growing Wheel


Can I come and interview/film/photograph GrowUp?

Yes, sure! We’d love to have you over. We currently hold monthly Media Days at Unit 84, so if you are interested in booking a slot email info@growup.org.uk with the title: Media Day Request and we will get back to you ASAP with available slots. Kindly note, that we can only accommodate 5 visitors at any one time during a Media Day. These sessions run from 10 am until 12pm which involves a tour of the farm followed by a Q&A session with our co-founder and CEO, Kate Hofman.

Can I visit the GrowUp Box?

Yes! The GrowUp Box is open to the public in Spring and Summer and closes for maintenance purposes in Autumn and Winter. We love meeting new, friendly faces at the Box so every Saturday in Spring & Summer from 12-2pm members of the GrowUp team and some volunteers will be on hand to explain how the system works and show you what’s going on. You can check here for details of our Spring opening times.

When the GrowUp Box is up and running we leave the shipping container locked up unless we’re there. That means from the outside you can see the plants growing upstairs in the greenhouse and the fish tanks inside the container through the port hole on the side. If you want to really see how the Box works, its best to come along when we’re open through the spring and summer.

Is the farm open to the public?

Unit 84 is a working commercial farm, so people aren’t able to walk around freely but we will have a visitors centre onsite to demonstrate the technology we’ll be using and we plan on holding monthly open days in the near future.

Can I come and visit the farm?

We are so glad you would like to come and visit Unit 84. Unfortunately, we are not currently holding Open Days to the public but are planning to in the near future. Kindly check our events page frequently for updates.

I am a student and I would like to include GrowUp in my research.

As I’m sure you can appreciate, we are a small team working on a big project which means we have limited capacity to do stuff that isn’t growing salad and farming fish. We will try and answer as many questions as we can, however, please fully read our detailed number of FAQs on our website to see if you can answer any of your questions beforehand. If you still have questions that need answering, kindly send a list of your questions through and we will try our best to set up a Skype interview.

If you have research questions and are able to visit the GrowUp Box in Stratford, London then you could also email sam(at)growup.org.uk to arrange a box visit tied into an interview session.

Comments are closed