Yes perennial plants only have one flowering time, it can be longer or shorter but once they've flowered that is it for the year. The clematis will have fluffy seed heads that will look pretty too. The rhododendron will flower over a longer period that the clematis.

The rhodo will need to be kept watered and fed during the summer as that is when the flower buds for next spring are formed.

The clematis will need pruning - an area of total ignorance for me. I hope someone will be able to advise you about when and how much to prune. Get it wrong and kiss goodbye to flowers next year.

Is that a montana clematis, if so theres no need to prune.

We have to serious prune our montanas Cookygirl or the are right over the top of our potting shed roof.

Yes, montanas will happily spill out of their allotted space given half a chance but respond well to being chopped back soon after flowering. Mine will be getting a short back and sides this coming week and I know it will give an equally good if not better show again next year.

Thanks for the replies, I now need to understand how much I should prune. Lots of leaves appearing now. :-)