Greenhouses & Rooftop Growing - why some urban farmers are looking up to move forward


Last week we covered Vertical Farms. Namely the of the indoor variety, using some form of hydroponic method. But we now know that the practice of indoor growing isn’t without it’s critics. The number one problem? Energy consumption through artificial lighting. So what solution do the critics such as Andrew Jenkins point to when they insist that “vertical farming isn't a miracle solution to food security”. Well according to Jenkins, one way to solve the problem of artificial light - use urban greenhouses:


“Although they can’t grow as much food, rooftop greenhouses need at least 70 per cent less energy for each square metre of growing area than artificially lit vertical farms.” A. Jenkins, 2018 


It would seem like the ideal fixer to any of the problems faced by the big Vertical Farmers out there. But, as highlighted above, when the amount of food grown doesn’t match up, is it worth growing in rooftop greenhouses? Let’s backtrack a second. The yield for Urban Greenhouses might not compare to Vertical Farms, but surely there is still merit in this method, when compared to field 


Tower Farms are a US based supplier of aeroponic growing towers for use in urban greenhouses. They enable entrepreneurs and businesses to start their own urban food supply with their products. According to Tower Farms, through using their systems, ‘you can grow up to 30% more food, 3x faster — while saving up to 90% more space and 98% more water compared to traditional growing methods. Plus, there’s no digging, weeding, or watering.’



Not bad at all. So if this seemingly more sustainable system of growing has the potential to positively impact the looming food crisis in our cites, then what’s the potential? In the majority of western cities, our building’s rooftops are designed primarily to keep rain away and divert it elsewhere. For example, the concept of applying a green roof to buildings focuses around reversing that process. By collecting the rainwater and distributing it to plants, green rooftops can be a force for cleaner water, energy savings, and most importantly, food production.


The opportunity is best summed up by Toronto-based 'Green Roof for Healthy Cities': The roofscapes of our cities are the last urban frontier—from 15 percent to 35 percent of the total land area…”. When you look up in any urban environment, it’s hard not to picture a healthier environment if our rooftops were covered in greenery: the existing potential is palpable. We already know the positive impact on the local climate green roofs can cause; we already know the reduced carbon emissions we’d emit if we cut down the food miles from traditional farming; and now we know the potential for food production in urban greenhouses, as well as the potential for available space.


As with vertical farming, the industry of commercial rooftop greenhouses is a new one, but there are already some burgeoning companies carving a path for urban growing in this way. So who got their first?



The Key Players in Rooftop Growing Game



Back in 2011, Lufa Farms opened the first commercial rooftop greenhouse in Montreal, using no new land, capturing rainwater, recirculating irrigation water, reducing energy use, composting green waste, using biocontrols instead of synthetic pesticides, herbicides, and fungicides, they were able to start delivering produce to members on the same day it’s harvested. Since then, Lufa opened two more rooftop farms with more advanced system as well as a fleet of electric cars to carry out home delivery. In the coming years they also plan to open more greenhouses in Quebec’s urban centres as well as branching out into the US.



It would be hard to discuss commercial urban greenhouses without mentioning Gotham Greens: probably the industry’s most well know venture, this Brooklyn born business started by growing greens and vegetables to their local community. Today the company operates over 170,000 square feet of technologically advanced, urban rooftop greenhouses across 4 facilities in New York City and Chicago. Gotham Green’s also boasts to be 100% clean energy powered, including their 20,000sq ft greenhouse above a Brooklyn branch of Whole Foods - which is about as low as your food miles can go if you’re buying from a supermarket.


New Yorkers have always romanticised the 'tar beaches' of the city's skyline, so it's unsurprising that it's home to a number of rooftop growing ventures. One company that is breaking the paradigm of modern greenhouses is Brooklyn Grange: who operate the largest soil-based rooftop farms in the world, producing 80,000 lbs of organically-cultivated produce per year. On Brooklyn Grange's farms, soil is craned directly onto the roof, and vegetables are planted in the traditional method. Of course, the main issue here is existing buildings having to deal with the extra weight of the soil - which is why B.G. partner with structural engineers at the beginning of any new farm set up.

Brooklyn Grange makes the case for urban farming very clear, showcasing that high-tech or even hydroponic solutions are not required to start producing local food in our cities with under-utilised space. Their rooftops also extend an arm into the community through utilising their space for events, yoga classes, youth workshops, dinners, and even weddings.


One of the key benefits of using soil on city rooftops is that a greater variety of vegetables can be grown. Brooklyn Grange might have a lower yield per square meter compared to vertical farms, but it doesn't just sell 'leafy greens' to it's customers - which is an important distinction in the long term for urban farming.


‘Tomatoes are another of our biggest crops: we have a couple dozen varieties planted. We are also growing peppers, eggplant, kale, chard, carrots, turnips, radishes, chicories, ground cherries, pac choi, herbs, beans, and many other exciting crops! Diversity is good for our sales, enables us to bring more flavours and variety to our CSA and market customers, and is an important aspect of sustainable soil and pest management.’ - Brooklyn Grange, 2019


With that being said, it's hard to ignore the advantages that greenhouse growing brings: allowing for moderated climates, whilst still benefiting from natural sunlight. It's perhaps not surprising then, that when it comes to new ventures in sustainable food, one European country is going full speed ahead with the greenhouse method.



A whole city of Greenhouses



Hungary recently announced plans to build an entire city of carbon-nuetral greenhouses to sustainably grow food, near its borders with Austria and Slovakia. The development is a partnership between German developers FAKT and energy providers EON [who] are collaborating with the Hungarian government on the project. The site in Hegyeshalom-Bezenye is set to create 5000 permanent jobs, with 1000 new homes being built as part of the development, along with hotels, shops, and schools - totalling an area equivalent to 500 football pitches.


Hungary's minister for agriculture, István Nagy, who is championing the development, has said that it will bring about an "epoch change for agriculture". Indeed this project will serve as a great case study for countries seeking to replace traditional, high-emission farming with carbon-nuetral sustainable farming, but there is much still to be learnt before we can claim this as a victory for sustainable food. The implications of creating a whole new city for greenhouse growing are yet to play out. In fact this story is not an unfamiliar one.

Traditional field farming has been known to clear land for food production. Between 2000 and 2010, industrial agriculture accounted for 80% of the planet's deforestation. And whilst Hegyeshalom-Bezenye may have a wealth of sustainable power and infrastructure behind it, the tabula-rasa approach of farm land has had its pitfalls in the past. Creating a new agricultural development outside of cities also means that any food grown there will still have to be transported to higher population regions, even if the overall food miles are reduced.



That is not to say, however, that this development is not a step in the right direction in terms of the methods and, ultimately, the carbon footprint of such ventures. However, we already know that one of the main challenges to a sustainable future for the planet will be helping our urban populations to be self-sustaining in their own right. In our view, this will be best achieved by creating solutions that work with and inside of the cities we already have - like the success stories of Lufa Farms, Gotham Greens and Brooklyn Grange among others.


As usual, to get a better insight into what the future holds for the industry, we caught up with one of the key organisations helping it to grow. Tower Farms supply aeroponic growing towers to would-be urban farmers to provide a straight forward and cost-affective solution to producing food in the city:


"...One of the biggest challenges lies within the accessibility for growers to get the appropriate capital to set up their operations. Banks and financial institutions are more willing to bet on traditional farming practices and shy away from non-traditional practices such as vertical growing. In turn, this leads to hydroponic growers starting much smaller operations that are harder to scale and make profitable. This issue is the exact reason why Tower Farms became a direct lender and provides low interest financing options to growers wanting to get started. 


Additionally, old [American] zoning laws plague the urban farming movement by hindering greenhouses and agricultural practices within the city limits. There’s also an opportunity for growers to find better ways to brand their products and create customer loyalty within the industry.”

- James Coffman, Director, Tower Farms, 2019



As with last week's discussion, the core of the conversation at some point has to come back to long term financial viability. Key to the growth of any industry is finding the right investment. As James Coffman describes above, the big players in venture capital and commercial banking can be slow to lend their trust (and money) to emerging markets like urban farming. But as long as the populations of our cities continue to swell, the problem of sustainable food resourcing becomes greater and greater. At a certain moment in time, the tipping point is going to occur where the established powers will have to accept and embrace more sustainable methods. Whilst Tower Farms and many of their customers might be outliers in 2019, in 30 years time, we are going to find their services all too important.