There has long been a need in the UK for the recognition that flat roofs can be used to grow food. Rooftop gardens have become a common feature in North American cities as well as in Asia and other countries where land for growing food is scarce. So it was with some joy that I approached this article on the BBC web site.
A supermarket in Crouch End, London is growing food on its roof at last. They have about 450 square metres of space which has been turned into a food garden. The owner calls it a “… a farm on top of a supermarket” which I think is stretching things a bit; a garden yes but I do not know of any farms with just 0.045 hectares of land. Another quote says the project has a very low carbon footprint because all the equipment has been donated. Nice idea but plastic compost bins and other stuff has to be manufactured and transported to the site so does have a carbon footprint even though somebody else has paid!
Not that I am criticising what they are doing, I have long argued that using city roofs to grow food is exactly the way to go. There are some superb examples around the world where aerial gardens work well. In Singapore Changi hospital grows food on its roof and uses it to feed patients. Not only does that use what was redundant space it also give patients healthy and tasty food and maybe even saves money.
Many of the projects use hydroponics which, at the present time, use fertilizers which are not sustainable i.e. they are made from oil and use huge amounts of energy in the production process. Some argue that there is nothing wrong with that as long as it feeds people but the organic argument is that it relies on heavy imports of nutrients which is both unsustainable, costly and does nothing to address the issue of declining oil supplies.
There are alternatives like growing in containers using peat free, or home made, composts and making nutrients from composting food waste. Some years back a really innovative project in Australia tried to use a continuous worm composting system to make nutrient rich compost from restaurant food waste. The idea was to grow leafy crops in the compost on the roof which would then be used in the restaurant thus completing the nutrient cycle. There was never any news of whether it worked but technology has moved on now and such a project would be perfectly viable.
For me any food grown on roofs, or in gardens, has to be ‘organic’ i.e. not just free of pesticides but sustainable. That means no artificial fertilizers. I would really like to see some innovation in plant based nutrients and container growing which would produce a sustainable system that is low maintenance and productive. That would also have to include some way of watering automatically maybe triggered by sensors when the compost dries out. There are easy ways to do that it just needs the will and vision to see an alternative to existing growing systems. And a nice big flat roof!
More information
- Changi Hospital rooftop micro farm
- University cafe rooftop garden in Canada
- Rooftop gardens in Eygpt
- For a round up of rooftop garden projects see this page . (Not all the projects are about growing food.)
Related posts:
