Posted: 09/02/2014 at 08:31
I can't think of any reason why you shouldn't grow these in the same bed, treating it as a sort of potager. Which way does the wall face? What variety of clematis are you thinking of?
My concern would be for the roots of the clematis, as there'll obviously be some harvesting and replanting of kale and garlic etc don't plant them too close to the clematis to avoid disturbing it's roots.
Have you thought of growing the Italian kale, Cavolo Nero? It's absolutely delicious and looks much more attractive (I think) than the usual curly kale so would suit your potager style of gardening