In article ,
says...
After 4 years against a north facing fence, this thing is now 6 feet
high, but shows no signs of flowering. Although the plant looks
generally vigorous, the leaves don't look too healthy.

http://i55.tinypic.com/141jl0.jpg

The soil is a little on the stony side and it doesn't get a lot of
direct sunlight, but the mopheads grow well in the same location.
Any advice appreciated.

6' is still a baby, they generally take 6-10 years to start flowering and
north facing will take longer.

Tatty leaves after winter is normal but tatty leaves now indicates either
its much too dry or suffering from wind exposure which it doesn't like
very much

If the tatty leaves appear to be notched its vine weevil damage
--
Charlie Pridham, Gardening in Cornwall
www.roselandhouse.co.uk
Holders of national collections of Clematis viticella cultivars and
Lapageria rosea