Just a quick note that if you live in an area with Japanese beetles and these are blooming when the J beetles are around, white clematis flowers will get eaten IME. In my area I am fine with spring blooming whites but have decided not to plant any more white or really pastel summer flowering clematis because that coincides with our J beetles.

So the beetles prefer white or pale colored flowers over the darker ones? That's pretty interesting in a weird way :-) I wonden if there is a difference in taste due to the heavier pigmentation............

Knock on wood, those creatures have yet to be much of a presence here in the PNW.

Yup, they eat pale flowers first, and tend to ignore more richly colored ones. They often land on (and stain) light colored laundry drying on the line. So I think it is a visual attraction rather than taste.

They (the J. Beetles) were horrible on my Blue Satin Rose-of-Sharon last year! I'm hoping the hard winter we just experienced will have killed some of them off.

I hate to tell you, but even after zone 4 winter temperatures, they continue without pause.