You could have an annual such as Black eyed Susan but would need to sow several and use a few canes as well I would think. I grew a lovely large pot of those one year facing south-west. Clematis would be nice too and will live several years if you keep the roots well shaded and cool. Again, you would need some canes or wires as the drainpipe would be too thick for its tendrils to hang on to.

Thank you, pennyfarthin, I am going to try and put something round the drain pipe first to support the plant the black eyed Susan sounds lovely, and a clamatis sounds good also. Thank you once again.