When in doubt, go bigger :-) 'Guernsey Cream' is not a huge clematis, however when growing any clem in a container, I tend to err to the generous side. Even a small clematis can generate a pretty good size root system. I'd consider the minumum size to be the equivalent of a 3G nursery container but generally go larger whenever possible. A container with a diameter of at least 18" and a similar depth is about ideal for most.

Perfect! Thanks Gardengal,

sorry to rehash an old thread, but when is a good time of the year to pot up?