Plastic bottles and bags: precious jewels for container gardening (Willem)

On September 12th, 2007 Riziki SHEMDOE sent the following message :

“I have been reading on the container gardening experiments that you have been doing. This has encouraged me to put up a proposal on introducing this technology to the rural semiarid areas of Tanzania where normally crop production is very poor due to drought and poor soil fertility. I am requesting to know whether there are some best practices from the third world countries that you have come across regarding the use of this technology in improving rural food security and poverty alleviation? I will be grateful if you share with me some of the best practices so that I may use them to strengthen my proposal. I look forward to reading from you.
Kindest regards,
Riziki. “

Riziki Silas Shemdoe (MSc)
Institute of Human Settlements Studies,
University College of Lands and Architectural Studies
P.O.Box 35124 Dar es Salaam, Tanzania

Here is my reply :

The easiest and most practical way for people in developing countries to practice container gardening is to collect a large number of plastic (PET) bottles and plastic shopping bags. It’s clean and cheap. Moreover, it helps to take care of our environment !

The plastic bottles should be cut in two : a shorter bottom part (the cup, used as a water tank) and a longer top part (with the stop still on), to be filled with potting soil. In order to cut the bottle in two optimal parts, define the length of the two parts approximately so that, turning over the top part (that will contain potting soil later on) and sliding it into the bottom part, the stop is touching or almost touching the bottom of the cup. If this is not the case the bottle will be rather unstable. Then, a small slit should be cut at the edge at two opposite sides of the bottom cup so that the top part of the bottle can be pushed into the cup until the stop reaches the bottom (short slits will open a bit). It is better to have the bottom cup a bit too long than too short (stability). One can always cut the two slits !

The bottleneck should be perforated at two opposite sides, close to the stop, to create drainage possibilities if too much water is poured in the bottle and to create water absorption possibilities from the bottom cup. Holes of 5 mm diameter are sufficient.

When filling up the inverted top part with potting soil, the soil should be well compressed in order to avoid larger air cavities in the bottle. I recommend to mix a water stocking soil conditioner with the potting soil, but if this is not possible for financial constraints, don’t hesitate to do it without.

During the first days, watering should be abundant to eliminate too much air in the potting soil. As the infiltrating surplus of water will run through the two openings in the bottleneck into the bottom cup (water tank), and as evaporation will be limited (only through the top opening of the bottle), one can save a lot of irrigation water and produce significantly more biomass with less water (less leaching of nutrients from the potting soil, and less evaporation).

Isn’t this a nice solution for some of our main environmental problems in the drylands ?
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The same advantages are offered when growing vegetables or young trees in the classical plastic shopping bags.

Fill up a plastic bag with potting soil for 2/3, and keep the two handles of the bag upright, simply by pushing them up and sustaining them with two pieces of a small branch or another support (one at each side of the bag). Thus, a shallow cavity is created above the potting soil in which water can be poured from time to time.

Don’t forget to perforate the lower part of the plastic bag a couple of times at the two opposite sides of the bag, e.g. 2-3 little holes (not slits !) at both sides approximately 1-3 cm ( 0.5 – 1 inch) above the bottom (and not in the bottom itself, so that a bit of water can be kept temporarily in the bag). Vegetables can be seeded or planted in the potting soil. Young tree seedlings can also be grown in such a simple plastic bag.
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FOR BOTH BOTTLES AND BAGS :

Considerable advantages :

(1) more biomass with less water (because of less leaching and less evaporation).

(2) eliminate plastic from the environment by burying the used plastic bottles and bags at the end of the growing season, e.g. when planting the tree seedlings in a planting hole (ecological cleaning).

Caution : avoid heating in the bottles or bags by keeping them in half-shade or in places where the number of hours of sunshine is limited (not a full day).

Please set up some experiments and discover the real advantages of gardening in plastic bottles and bags, not in the least the provision of food security and the alleviation of poverty. That’s what I call a success story or best practice for sustainable rural development. I hope that once my preaching in the desert will be heard.

PS. Have a look at my former postings to discover pictures and drawings.

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RIZIKI’s IMMEDIATE REPLY

“Thank you so much, Prof., for the explanations and the methodological approaches. I will try something in this area. This will really relieve our poor people in the dryland-areas to improve their nutrition. Similarly this will assist in improving the environmental sanitation by giving use values to the plastic bottles that are being thrown everywhere in our cities. Thank you.
Riziki.”

Published by

Willem Van Cotthem

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

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