A lettuce table

This is an idea that has been used by the UN in countries that have suffered natural disasters. It was used extensively after the earth quake in Armenia, Columbia. I cannot claim any originality for the idea which was developed by Cesar Marulanda. A brief account of the project can be found at www.carbon.org/

Although developed as a simple method of growing food in developing countries it has a place in food production in urban areas of the UK. Many inner city districts share common problems with less developed countries. Low fixed incomes; the lack of access to fresh food due to the demise of local shops and the lack of personal and public transport to reach out of town shopping areas are just some of the problems.

(Click on an image to enlarge.)

lettuce_bench1 The wooden tray with rain cover hinged up.
The drain with watering can to catch nutrient runoff for
lettuce_bench2 Salad leaves and wild rocket 16 days after sowing.

The growing system consists of a waterproofed wooded box with a hole in the centre. My boxes have a plywood base and softwood sides. The waterproofing is black plastic and the drainage hole uses a grommet with a 15mm plastic pipe with tap pushed through from the bottom. The tap is not really required but was added so that some measurements of water added and waste water flow to the can could be taken.

This way of growing could be called hydroponics because it does not use soil and all nutrients are added to the irrigation water. Any organic gardener growing using organic grow bags, or pots, would also fall into this category although many would not like that label!

Research is being carried out in many parts of the world on the integration of organic growing and hydroponics. Hybrid hydroponics is being developed in Australia where food waste from a restaurant is being used for worm composting which is then used to make a nutrient solution to feed to beds of salad crops which go back to the restaurant. True closed loop recycling. In some cities the growing takes place on roof tops making use of waste
heat and CO2 from the building beneath.

Update Feb 2009. This article was written a few years ago. Since then I have abandoned trials with this type of growing systems but the recent rise in food prices, and the current financial problems, means that more people are looking at ways to grow food.  Perhaps the way forward is to use garden compost and leaf mould as the growing medium and dilute liquid comfrey as the feed. There are many containers that could be recycled making it a very sustainable system.