Low-tech vertical farming: an interesting discussion (Kris DE DECKER / Willem Van Cotthem)

Read at : Low-tech Magazine


How to make your own low-tech vertical farm

Vertical farming has become a popular idea, but what is mostly forgotten is that the energy required for the operation and construction of vertical farms largely negates the ecological advantages. This also applies to small-scale systems, like those of Philips (a concept) or Inka Biospheric Solutions (a product).

A while ago two New York ladies made headlines with their “Window farms“, described as a kind of low-tech indoor vertical farming system (illustration on the right). Upon a closer look, however, I found the method to be rather high-tech and cumbersome, in spite of the use of plastic bottles. A window farm is based on hydroponics, it makes use of lamps, pumps and electricity, it still requires you to buy quite a lot of new stuff, and the whole thing would surely come crashing down if I were to install it.

The Belgian professor Willem Van Cotthem seems to have designed a do-it-yourself vertical kitchen garden system that truly deserves the low-tech label. On his blog, “Container gardening”, he explains how to transform normal plastic bottles into efficient containers (and a container rack) for growing all kinds of plants, even young trees (to be transplanted when reaching sufficient height). The beauty is that the water supply can be automated without the use of electricity, and that his way of installing a vertical garden looks much simpler and sturdier.



MY COMMENTS (Willem Van Cotthem)

See also: http://containergardening.wordpress.com

The publication of this article by Kris DE DECKER in LOW-TECH MAGAZINE created a lively discussion since March 2010.

Readers were interested in tutorials for creating a vertical, urban indoor garden.

Others found it problematic to use plastic containers due to their chemical composition. This is a universal question coming back several times at different fora.  Here is my reply published by LOW-TECH MAGAZINE on March 17, 2010 :

“As a biologist, I agree fully with experts alerting us for the threats of certain components in certain plastics. But I don’t agree with the overall doom scenario written by some journalists. Moreover, I don’t believe that “dangerous” plastics will disappear within the next decades. They will slowly be replaced by “less dangerous”, e.g. biodegradable ones. In the meanwhile, we are recycling some in the developed countries and the bulk of plastics is simply going to waste dumps where we cover it all up with a good top layer of soil.

However, in the developing countries most plastic objects are finally littered. Pots, bags and bottles are literally covering the streets or hanging in the trees as plastic flowers. That dirt causes more diseases than the plastics themselves, e.g. by being the preferred niches for a panoply of germs on the spots where the kids are playing in the dirt. “Recycling” plastic bags, pots and bottles by using them as containers for production of vitamin rich vegetables or seedlings of fruit trees is less dangerous than leaving them flying around in the environment. I agree with Levi that wealthy people, who can afford buying earthenware or glassware for gardening, shouldn’t use the plastic trash. But for the poor people and school children in developing countries, gardening in plastic bottles is not only a contribution to food security, but also to public health. And it helps to keep the environment a bit cleaner and greener, particularly in the drylands.”

Kris DE DECKER, the author of the article, agreed with my views and added some magnificent comments on health risks due to plastics and differences in attitude between the developed and the developing world. He concluded his contribution with: “Also don’t forget that a large part of the rich world is depleting its underground fossil water reserves at an alarming pace, the USA being a good example. The poor drylands that Van Cotthem originally designed his method for, might not be that far away:


The latest comment, posted by “plastic soil?”, contained a number of questions concerning the soil conditioning compound TerraCottem, developed at my laboratory in 1983-1992.  I had the honour of submitting the following reply for moderation by the author:

“You are absolutely right: the TerraCottem soil conditioning compound my team and I developed at the University of Ghent is certainly not “low-tech”. We never claimed that. On the contrary, this mixture of water absorbent polymers, mineral fertilizers, organic substances, root growth activators and carrier material, e.g. volcanic rock (all together more than 20 different substances) is indeed a high-tech compound, intended to solve different dryland problems in one go: drought, soil poverty, lack of organic matter, poor root development, low yield, soil compaction etc. Our main objective was to create a useful “method” (a tool) to combat drought and desertification by mixing a small quantity of a granular compound per square meter in dryland soils to improve their water retention capacity, their organic content, the microbiological activity and the biomass production capacity, using only a minimum of irrigation water or rain. TerraCottem soil conditioner is produced by a spin-off company of the Ghent University since 1990. It is applied in more than 50 different countries with approval of the national safety administrations and services. It is absolutely non-toxic (since the nineties I have eaten a lot of it to show its non-toxicity) and has nothing to do with plastics. All soils treated with it on the different continents are nowadays significantly better (more productive) than the ones before treatment. In order to avoid assumptions one can always ask the producing company to answer a number of additional questions.
Anyway, TerraCottem has nothing to do with vertical farming.”

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Author: Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.