It depends on which clematis they are, what do the labels say?

Moongrower is right. do they have name labels if yes add them to the comments box below this and we will get back to you.
welcome to GoY

always better to plant in the ground. as they will need a lot more attention when in pots/planters

There are Clematis that do fine in large containers Eamonn, yes easier in the ground, but, perhaps, little or no ground to plant in or poor soil conditions.