Hello Guest lots of choice - depends on the look you want to achieve. Structured, Modern, old Cottage, Courtyard, open or shade etc and do you want to minimum care and watering? Which way does it face, uses etc? Why not Join and post a pic of your decking for some good ideas?

Non specific question, Guest - do you mean plants for pots sitting on decking, or plants for the ground around the decking? If the latter, how big an area do you have available? If pots, how many pots have you room for - if only 3 or 4, then you need nice specimen ones, and for that, we need to know whether its in sun or shade, windy and exposed, warm and sheltered.... Perhaps you could repost your question with more information.

cannae beat trailing petunias and trailing nastursiums or try climbing roses in large tubs