Posted: 07/06/2012 at 10:46
Clematis are very hungry and thirsty plants so be prepared to feed and water regularly during the growing season and alo protect the roots form freezing in winter as they are more exposed to frost in a pot above ground.
You could underplant with pelargoniums for the summer or for a permanent planting try evergreen grasses such as forms of carex buchananii or blue fescue. other than that, any hanging basket subject such as trailing lobelia or petnuias would do well but would need replenishing each year.
However, I personally would choose a mulch of slate or gravel with occasional applications of wildlife friendly slug pellets to get the nasties that might eat young clem shoots.