By Emerion
United Kingdom 
I have a North facing wall, which is 5 feet tall with 18" of trellis on top. What climbers would thrive there, given that above the wall will be in full sun from mid spring to mid autumn, but below that is shady? Would a shade loving hydrangea, like petiolaris be happy? Or do I want a sun lover that will climb up towards the light? I don't want to end up with a top-heavy plant with bare stems below the trellis. Anything that grows above the wall will have to tolerate strong winds as well as sun. Our soil is slightly acidic.
30 Apr, 2017
Answers
There's quite a range of plants that will grow in this situation - some are climbers, some freestanding shrubs that prefer to be against a wall, like Garrya elliptica or Pyracantha. There's a comprehensive list, including clematis, in this link here https://www.rhs.org.uk/advice/profile?PID=467
Schizophragma is mentioned, along with Pilostegia, but if you live in a very cold part of the UK, they may not do too well.
30 Apr, 2017
Thanks very much Loosetrife2 and Bamboo. I hadn't even considered clematis! Now the fun bit!
30 Apr, 2017
Chaenomeles, Japanese quince would be my choice. Can be trained as a climber and would be suitable for a north facing wall. As it is deciduous there would be no problems when the worst of the weather present. Excellent early season flowers; reds, pinks, oranges or whites on almost bare stems followed by fruit for jams and jellies. Would be a delight in any garden.
30 Apr, 2017
Clematis like their feet in the shade and head in the sun so I would suggest any variety of that to you.
30 Apr, 2017