I would put it in the ground and let it grow up the trellis, but that's just me, others may disagree.

Unless the pot was a very large one, i don't think it would do that well in one, plus, you'd still need to put a frame in there for it to climb up.

It's classed as a 'group/category 2' clematis, which means an early to mid season flowering plant and it'll need only light pruning because its flowers are formed on last years growth.

Thank you Louise

Forgot to say i think i will put it in the ground Louise, i havn't got a big enough pot after spending enough this week on plants! so in the ground it will go which will be less disturbed than a pot! though i will be putting egg shell around!

You're welcome Bm, i adore clematis and have a few here.
You can also plant them so they grow through shrubs where they'll use it to cling to, i like to do that here, infact, most of mine are planted like that, i only have 1 on a trellis and 1 on an obelisk.

Good idea to protect it from slugs, they'll love the nice new growth it makes, a couple of mine have been stunted due to slug damage.
Also, if its new home is quite sunny, shade its roots a bit because traditionally they like their roots cool. Do this with some pebbles/bark/other plants.
I have to say though (here i am again, going against the norm!), i have some without shaded roots and they're fine :-/

And - plant it deeply. This helps if it suffers from 'Clematis wilt' which can strike really quickly - one minute you have a healthy plant, the next, its withered and floppy. If you plant deeper than the pot level, then you may well get new shoots appearing from the rootball. This has happened twice to my 'Vyvyan Pennell', and it DOES work.