Posted: 16/05/2017 at 17:24
I have grown all sorts of clematis successfully in ceramic pots and also plastic - getting them ready for life in the ground and, lately, for moving to a new garden. They are all still there waiting to be planted and not wilting at all tho in full sun in 32C today. The only one in trouble is a young one from last spring that has been "pruned" by snails but is now showing signs of regrowth.
I wonder if maybe yours got frosted recently or if you have a naughty slug or snail or 3 that are chewing the stems at the base. Both would cause wilting. Try some slug pellets or going out after dark witha torch and picking them off or both methods to be sure. If the root system is healthy it should recover.