Winter Clematis

Hi All.
May seem a bit early but winter does seem to creep up on us so best to prepare now.This year I purchased a Clematis Picardy for container.Ideally it should perhaps go into greenhouse over winter but we have gone a bit mad this year and have over 40 containers!! ranging from small to large so greenhouse may be a bit full after re-potting some plants.
I will move clematis to a west wall but I have been reading about the container/plant fleece you can purchase for added protection.There seems to be either 2 varieties or 2 ways to use them.One is to cover just the container with fleece and the other is container & plant.

I would of thought that since the Picardy is a group 3 and therefore pruned to 1ft (30cm) in spring I would only need to protect container & just one foot of plant??.
Any thoughts please would be appreciated.
Thank you

 

It's worth noting that fleece apparently can only protect a plant in under a minus 2 degree of cold, any colder and it's not able to protect.
I heard this last year from a reliable source.