Too late to feed now, the growing seasons coming to a close. Worth trying the milk remedy though - 1 part cows milk to 9 parts water, but you can use 2 or 3 parts milk to 8 or 7 parts water. Spray thoroughly, all parts including under the leaf, till run off. Repeat frequently if its bad. Works best if applied in bright light or sun, and if the mildew is in the early stages.

I've had the same problem, Cam, and though I tried the milk and water it didn't work for me. In the end I cut them back to about a foot and now there is new growth. I think it's the weird weather that's the real problem.

Some years ago I also had this problem especially with Clematis 'Comtesse de Bouchaud' I cut them back when it appeared and found after putting a handful of Epsom salts around them every 6 weeks in the growing season it no longer happened took a couple of years. I do think that after the early flowering clematis it has not been a good year for them.

Thanks Drc, I've recently bought a 1 ltr bag from Boots so I shall try next Spring.