Posted: 03/02/2018 at 11:46
I have something similar - Lidl were doing them last year - two made of fibre and resin I think, the Lidl ones most probably some kind of plastic.. First, important to ensure there are drainage holes - I made them a few centimetres up from the bottom to prevent them filling with water. Then make sure they have a filling more substantial than multi-purpose compost which dries out too quickly.
I have a camellia in one and it does very well. I have a pair which have alstroemeria in, and they seem to be doing well too, and the colours are stunning. I think you can put whatever you want in providing you watch the watering as they can dry out quickly in full sun, and you may need to bubble-wrap then or pop them in the GH in winter if you hav something more delicate in them.