@jzs147 , I agree that deep soil is not the best option for growing. I was thinking of buying the 1500 litre bag from the above vendor, and just adding about 40-45 cm of medium and folding the sides down for a bit more strength and easier access.
- Capacity: 1,500 litres
- Dimensions: 85 cm high x 150 cm diameter
It's also good that there are no drain holes underneath, as that would allow access for termites which like to eat the sugars in the roots and subterranean stems. The plants go yellow and fall over once the remaining thin stem breaks.