Miriam, hydrangea petiolaris is a wonderful climber for shade. It 'sticks' to the wall or fence that it is growing against and therefore is not super ideal for a wire fence but if your fence is wooden its a great choice. It has clusters of lovely white flowers. The clematis that you mentioned is, I think, Guernsey Cream, and is also a great climber and will do well in a shady spot. It is a type 2 clematis which means that it blooms initially on last seasons wood so dont hard prune in the spring and do a light prune after the first bloom flush and it will bloom again later. I dont know much about your growing conditions but both the above plants like adequate moisture and good drainage. I am unfamiliar with the Japanese hydrangea so cant help there. Good luck. Kat