In article , Paul Flackett
writes

I'd agree with that and particularly recommend either Polish Spirit
(purple) or Madame Julia Corevon (deep red/pink). However I've not had
too much success with Clematis in tubs. They're great the first year but
soon use up all the goodness in the compost and struggle the second
year. Also they're not too forgiving if you forget to water them.
Another thing I've noticed about the viticellas is that they're rather
susceptible to capsid bug damage and also mildew (especially in the sort
of 'summers' we've had the past couple of years).

They will grow in tubs for years, but you do have to do some work.
Turfing them out in the dormant season & reducing the root ball (with a
large knife) and re-potting. Watering is absolutely essential. No
plant that will grow to 10ft+ and flower for almost 3 months can do it
without food or water.

Mildew can be controlled though I notice it more on the texensis & their
near relatives than the vits. Planting where air can circulate easily
helps too. Capsid bugs? Not here, but may depend on where you are.

Purple clematis to go with pink roses: Viticella Etoile Violette
(stunning thing), Polish Spirit, Little Baz, Elvan, Black Prince,
Mikelite. (The last two not strictly vits, but enough in their
'bloodlines' to mean small flowers & hard pruning).
--
Rachel
Clematis Web Site
http://www.ukclematis.co.uk/