Roofs you can eat

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Since 1 January 2011 Annelies Kuiper has been known as the Roof Farmer - the first in the Netherlands - and has spent her time transforming unused city roofs into attractive vegetable gardens. A vegetable garden on your roof has all the advantages of an ordinary green roof, with one additional benefit: you can eat it. From your roof to your plate.Starting with her own roof, which served as a test case, she set out on her mission to conquer colourless flat roofs, with the occasional sideways excursion along the way. At the Dutch music and cultural festival Lowlands 2011 she helped to build a vertical garden, an impressive scaffolding structure consisting of 375 crates filled with vegetables which are being grown by the Roof Gardener. Annelies had long been interested in sustainable lifestyles and organic food, but some time ago she also developed a fascination with urban agriculture. People today are living more consciously, eating more healthily and want to know where their food comes from, so there is a growing demand for locally grown organic products. Now they are looking for ways to bring agriculture into cities. Roof Farmer meets this need perfectly: "Land is scarce in urban areas, but roofs... there are plenty of those."

How exactly does Roof Farmer work?

First of all I provide a design based on the roof owner's requirements, taking into account the roof area and its strength. I then create the roof garden and maintain it if required. Food harvested from the roof can be prepared immediately in the company canteen, restaurant, school canteen or under your own roof at home. I use organic seeds and plants, soft fruit bushes and fruit trees. They are all planted in a lightweight natural substrate. I get help from experts to assess the roof structure, supply the subsoil, apply for licenses and subsidies and design items like sheds, beehives and mobile chicken runs.

How did you arrive at the idea?

I have been interested in sustainable lifestyles, authentic eating and growing vegetables for a long time. It is the combination of city and country that excites me most. A new concept such as roof gardening for an old activity like growing food is quite a challenge. Last summer I was reading about empty buildings and the fact that eating organic food is becoming more important for more and more people. Well, I put the two together. The sustainability aspect came later: green roofs are better for the city because they store water, absorb CO₂ and create a greener, cooler
environment (insulation). What is more, a roof like this lasts 30 years longer.

Which roofs are suitable?  

Of course you can go from 1m² in a box up to 10,000 m². The condition is that it must be a flat roof and the structure must be able to support the weight. What you actually do is adapt your roof garden to suit the roof structure. As you can imagine, cabbages that put down deep roots will not do well in 20cm of soil. They will need at least 50cm, but that also makes the garden a lot heavier. I started out with my own roof above my kitchen. That is 12 m² and it feeds two people from spring to autumn. This winter I will be putting up cold frames so that I can have more of my own vegetables in the winter too.

How much does a roof garden cost?

You should allow between 90 and 125 euro per m² for installation. That is more expensive than a bitumen roof, but it is much more sustainable because your roof will last longer and it will also be much more attractive, for example if you should sell your house at some point. Over a number of years, an edible roof works out cheaper than a bitumen roof. Not to mention the vegetables that you grow yourself and therefore do not need to buy in the shops. That saves money too...

What can you grow or keep on a roof?

In principle you can grow anything on a roof, as long as you have a good structure with a deep layer of substrate on top, which is soil composed of lightweight material which absorbs water more effectively. The ideal vegetable roof incorporates a number of different cycles: you collect rainwater and use it to water your garden, you compost your vegetable waste after harvesting, cooked waste goes to the chickens, the chickens peck amongst the larger plants and fertilise parts of the garden, and bees pollinate the plants.

What are the advantages of having a vegetable garden on the roof?

I think the greatest benefit is that when it is time to prepare a meal you can have a look on the roof and see what is ready to harvest. Looking around you see the other roofs with their bitumen, green coverings or solar panels, and feel a sense of peace. You harvest what you need and half an hour later your roof vegetables are on the table downstairs in a pleasant, cool environment because your vegetable roof has provided such good insulation. Food does not come more local than that. You do not have to worry about opening times or cycle off to your allotment. 

What are the main differences from creating an ordinary vegetable garden?

You get a wonderful view from your vegetable garden. You have fewer problems with slugs, weeds and fungi. You have to climb upstairs to get to your garden. The elements such as the rain, sun and wind are more extreme when you are high up. The Roof Farmer takes these factors into account at the design stage.

Does it require a major commitment from the owner of a roof garden?

Gardening is mostly about relaxation, whether it is on the roof or in the garden. Some people play football with friends, others take courses in painting and still others enjoy creating a vegetable garden. Football helps you to get fit and a painter has pleasant views to look at but a gardener gets fit and enjoys pleasant views too, and he has home-grown vegetables to put on the table every day as well.

So what do you grow on your roof?

On my first roof I have got a lot of diversity: pumpkins, chard, kale, potatoes, lettuces, iceberg lettuces, tomatoes, strawberries, parsnips, carrots, sprouts, artichokes, leeks, cauliflower, nasturtiums, pot marigolds, French marigolds, Chinese cabbage, sweetcorn and runner beans. I have the same conditions downstairs as the roof upstairs, because there is a concrete base underneath. There are grapes, horseradish, mint, lemon balm, sage, rhubarb, red cabbage, cauliflower, Savoy cabbage, celeriac and fennel. In winter of course I have winter cabbage, and in the cold frame on the roof there is also spinach, turnip greens, lettuce, winter purslane, chard and rocket.

Do you think Urban Farming will be a necessity in future, looking at the environment and the need to supply food to cities?

Eight to ten percent of all fruit and vegetables could be sourced from cities. I think there really needs to be some interaction between what happens in the city and in the surrounding area. There are a number of inescapable factors that are becoming more and more important. Consumers want transparency; they want to know where their food comes from. Food kilometres are important: consumers prefer to buy local and regional rather than international. People are eating a healthier diet. Increasingly they are choosing organic products that do the least possible damage to the environment and respect animal habitats and the environment. That does of course include roof gardening, as well as making use of empty buildings and unused land. The advantage is that in this way knowledge about food and food production can find its way back into the city. Knowledge means that consumers will become more independent of large food producers and adopt a more critical approach. Have a look at the film Food Inc.; that is an example of how things should not be.

Were you already interested in Urban Farming before?

Yes, I had been following urban farming for a while, and some interesting reports have been coming out of the WUR (University of Wageningen). The Marconi project in Rotterdam, using a plot of unused land for temporary agriculture, and the experiments at Aquaponics - growing vegetables and farming fish simultaneously in a greenhouse - both attracted my interest.

Is the Roof Farmer a completely sustainable and organic concept?

It is not yet possible to be completely sustainable, because Roof Farmer is about investments that a customer needs to make in his roof. Sometimes things are not available or there is such a large difference in price that the customer chooses less sustainable materials. I do use organic seeds and plants and a natural substrate. The organic aspect is very important for me.  This way of growing food does the least possible damage to the earth, gets the best out of the vegetables and produces the highest nutritional value. Roof Farmer prefers to use recycled materials or materials that can be recycled.

There is more air pollution in cities; are you not concerned that this will affect the concept?

The plants use CO₂, which is yet another cycle. Some gardeners want to have more CO₂ in their greenhouses to stimulate plant growth. The majority of the problem with particulate materials comes from other countries. Influences from the continent are responsible for 73% of this, and we cause the rest ourselves through soot emissions, industry and agriculture. Natural sources do of course play their part too. The air above the North Sea is quite salty and regularly blows inland. All public authorities acknowledge that particulate materials are a major problem. That is another reason why green roofs and vertical gardens have become popular with municipal and provincial authorities. Plants are able to take up particulate materials via their stomas and roots. When it rains, they are washed off the leaves. In this way they purify the air. They absorb hardly any particulate materials at all.

Six months after starting, you have already won a Biodiversity Innovation Award in the 2011 New Venture business competition, which will no doubt be a major encouragement to keep going. What is the Roof Farmer's dream? 

 Yes, of course the prize was wonderful, especially hearing that people think it is such a great idea. In fact, that is a big part of what having a vegetable roof is about: the idea that you are growing your own vegetables on your own roof. The Roof Farmer dreams of having a number of roof farms to bring the production as close to the market as possible. That means using the vegetables from the roof in the restaurant downstairs or by a caterer inside the building, in a large company canteen, etc. As a Roof Farmer you are not only interested in growing vegetables and the plants that support them, but you want to know what will happen to those vegetables too: eating, preserving, disseminating knowledge about growing vegetables, the nutrients in food and what they do to people. What I would really like is to have a Roof Farmer company that makes the whole food chain visible: from producing seeds right up to the toilets where those vegetables ultimately end up (laughs)!