I have found this discussion interesting. It's good to learn the options and the advantages and disadvantages of each and how to get around some of the problems. I am glad that John Grimshaw mentioned the weight of clay as a disadvantage. That's a big one for me (as is using large particles of sand in the mix). I don't want to end up with a stress fracture from lugging around heavy pots. I kept wondering when that was going to be mentioned. Not all of us are able to have greenhouses and plunge beds either to make clay pots work. In a climate like mine where it is very wet part of the year and very dry part of the year clay pots have another disadvantage. In the wet times the pots can turn green or black on the outside. We've not compared them with wood which I use sometimes. It may not last as long as other materials, but Jim Robinett a number of years ago suggested that I might have better luck with Calochortus in a wet climate planting in wood instead of plastic. Sun on black plastic would not be to the plants liking and wood would help with drainage as well. Mary Sue