Urban farming is hot topic. You see it everywhere.
Small repurposed patches of land in neighbourhoods are teeming with lettuce, radishes and sunflowers. You can follow workshops to make vertical gardens from used soda bottles or buy a square meter garden kit at the home depot.
Our local convenient store gives you seeds and little pots to grow them in if you shop there and even Ikea is jumping on the bandwagon with a stylish little aqua-phonics setup for your living room.
Everywhere on the internet you can read claims that urban farming might be the way of the future. It could even be the answer to a looming food crisis. Just turn every roof, balcony and window sill into a garden, and we can feed the masses. Companies with green fingers are popping up like mushrooms and municipalities are putting their greenest foot forward.
And it’s a reoccurring topic on prepper websites as well as a way to provide yourself and your family with food. Buy big pots, soil and seeds and start sowing now before the shit hits the fan.
Since we have done several gardening projects we were curious about the yield that might come from one balcony garden. So we decided to research the question: “Could you really grow enough food on your balcony to feed yourself?”
Let’s start with the facts.
We don’t need an acute SHTF scenario like a global economic collapse or nuclear fall-out to have a very real food crisis on our hands.
Several academic sources predict that in 2050 more than half of the worlds’ population will live in an urban environment. According to current estimates Tokyo is going to count whopping 37 million inhabitants in 2030, and Delhi is not far behind with an equally impressive number of 36 million. And if you thought that was mega, the Chinese government is planning to combine Beijing and 8 other cities in the Pearl River delta to create the gargantuan mega-city of JingJinJi. Currently the nine cities together already have a massive population of 130 million. The merger would create a city that would outnumber Japan by population and would be larger than Uganda by area.
Chances are that feeding all the people in these mega-cities is going to become a huge problem. Fertile areas are sacrificed for building plots and cities themselves are turning into so-called food desserts. According to recent research published by the PNAS “one-fourth of total global cropland loss will occur in China. Urban expansion in China is taking place in the country’s most productive farmland and over large areas. Therefore, urban expansion could pose a threat to domestic crop production.” This development, which we not only see in China but all over the globe, is bound to disrupt food systems, threatens livelihoods and could bring about enormous environmental consequences like the loss of wetlands and consequential flooding.
Due to the lack of space for agriculture and other actors like soil erosion, depletion of ground water and dwindling numbers of pollinating insects, the output of food production is probably going to decline worldwide whilst the number of people we will have to feed is growing.
So could you feed a city with urban farming?
Methods like vertical gardening (stacked grow beds), rooftop gardening or technologies like aqua-phonics and hydro-phonics (using closed water circuits to irrigate grow beds) can indeed expand the output per square meter.
In 2012 Singapore -then housing 5.3 million inhabitants- opened ‘Sky Greens’, a food production skyscraper with a closed energy and water circuit that could produce up to 500 kilos of vegetables per day. Not bad.
And there are precedents that in times of crisis urban farming can save a starving population, like what happened in Cuba 30 years ago.
During the cold war Cuba relied for 85% of its trade on the Soviet Union. But after the fall of the Soviet Union in 1989 and the ongoing US trade embargo, Cuba became almost completely isolated. It had lost its most important trade partner, which meant less food to import and export. But what was even more severe, no more oil, fertilisers or pesticides.
To deal with the crisis the Cuban government called for a nation-wide restructuring of agriculture. Before the crisis Cuba had large-scale, monoculture state farms relying heavily on artificial fertilisers and pesticides. No oil meant no gas to operate the machines on the farms, no fertilisers to grow the plants and pesticides to protect te monocultures. And even if they could still grow crops, there was no gas for the trucks to transport the food to the cities. This chain of events led to acute food scarcity and hunger. In their strive for survival Cubans living in cities started to use every free plot of land, every flowerpot, every balcony or empty building to grow food. The government supported this grass-roots initiative by helping them to free plots of land and crash courses in organic gardening and pest control.
Almost overnight their agriculture went from mass production to hyper local and organic.
And up to this day most of Cuba’s food is grown in urban farms. Before the crisis they imported more than 70% of their food, now it’s about 10%, making Cuba almost completely self-sufficient.
The reason that it works in Cuba could be attributed to the fact that it’s happening on such a large scale and in forms of urban corporations, that if one individual would not have space to grow everything he needs, he could share, barter of buy whatever he can’t grow from someone else. It’s easier to establish bulk and diversity in food with bigger numbers of participants and more available farm land.
So it works on a larger scale in Cuba, but would it be feasible to grow everything you need in your urban apartment?
Let’s assume that you live in an urban environment and you can spare space with a window to shed direct sunlight on your plants and / or have some space for an aqua-phonics set-up with artificial light. In addition to that you have a balcony or a strip on your landing in your apartment building that you could use for growing plants. Let’s assume that would be an royal average of 10 m2.
How much space do you need to sustain yourself with traditional agriculture?
In order to be self-sustainable with a family of 4 you need approximately 2 acres or roughly 1 hectare (8000 m2). If you have a hard time visualising the size, this is one and a half times the size of a football field. This comes down to 1/2 an acre or 2000 m2 per person.
If you would live on a vegetarian diet and thus only use the land for growing crops, you need about 400m2 per person, which is 40 times more than the available space in an average urban apartment. Of course this number is based on traditional agriculture. Designing the garden in layers like a forrest (permaculture), stacking layers of grow beds in forms of grows towers or make constructions with hanging plants (vertical farming) could double, maybe even triple or quadruple your gardening space. But even then you’re still 360 m2 short.
We could take a closer look at the food that we would like to grow. Most sources recommend that you should grow tomatoes, eggplants, broccoli, potatoes and beans, which echoes traditional farming. But tomatoes, eggplants and broccoli need a lot of space to grow.
Growing sprouts and micro greens for instance might be an option to deal with lack of space. Sprouts and micro greens contain on average more nutrients than their grown-up counterparts, take up little to no space and can be ready to eat within a week. If you could easily obtain new seeds, growing sprouts and micro greens could be the solution.
But in a SHTF situation, obtaining new seeds might not be that easy. In such a scenario you probably want to use seeds as sparingly as possible.
We could select plants with the most nutrients and need a relative small amount of space to grow. The climate where you live is also very decisive in what and how much you could grow. If you live in a moderate climate , you could grow sunflowers, squash and kale, and if you live in a warmer climate you might choose to grow sweet potatoes, cassava and peanuts. You could raise meal worms and snails in stead of pigs or chickens for proteins, or try to grow fish in your aqua phonics system, and grow mushrooms on coffee grounds in your cellar.
Your best bet for to get as many nutrients as possible from a small surface would be growing potatoes, either normal or sweet potatoes. They are excellent survival food and contain almost everything you need (except B12 and D, zinc selenium, and are low on proteins and fatty acids).
Let’s do the math for a scenario in which we mainly grow potatoes.
A grown man who only eats potatoes needs 3kg a day which adds up to 1095 kg a year. To produce that amount of potatoes you need 1023 plants. Every plant needs at least 10 litres of soil to grow. The big black buckets to mix mortar in can hold 40 litres and are ideal for growing potatoes. You can plant a maximum of 4 potatoes per bucket, so you need 255 of those buckets. You could fit 4 buckets in 1 square meter thus in total you would need 64 m2. Potatoes take 120 days to mature, so theoretically you can harvest them 3 times per year. Thats means we can do with a third of the space if we would grow in batches: a third of 64 m2 is still 21 square meters.
That’s more than double the amount of space most people have in cities.
But technically, if you would have that amount of space because you also have an additional garden or terrace, you could survive on potatoes. Especially when you would enrich your diet by growing meal worms (an additional square meter) on the peels of the potatoes for proteins and fatty acids and a few lima or pinto beans (an additional 4 m2) for selenium and zinc. That would amount in a total of 26m2 in order to be self-sufficient.
But 26 m2 is the bare minimum. You’re really screwed if your plants die, the potatoes turn out to be smaller than expected or if you can’t grow them the whole year round because they don’t like frost. To be safe, you need double or triple the amount of potatoes you sow. So a minimum of 52 m2 would be more realistic.
And in this calculation we didn’t even took the depletion of nutrients in the soil and thus the need for a compost heap, the methods of watering your crop and storage for your stock and gardening equipment into consideration…
So on the whole, could you grow everything you need in your urban apartment?
Unless you live alone in a mediterranean or warm area, in a spacious loft with big windows and reinforced floors to carry the weight of all the buckets with moist soil and an enormous terrace, the answer would be no.
Sources:
Megacities and the Threat to Food Security
Organic Cuba without Fossil Fuels
Future urban land expansion and implications for global croplands
How Much Land Do You Really Need to Be Self Sufficient?
The 7 Layers of a Forest
Comparing Health Benefits of Microgreens to Other Nutritious Vegetables
Survival Food – 10 You Should Be Growing Yourself
Growing Enough Food to Feed a Family
Can you survive eating nothing but potatoes?
How to Grow Potatoes in Pots
How to Raise Mealworms
Complete Nutrient Content of Four Species of Commercially Available Feeder Insects
Top 10 Vegetables Highest in Zinc