I have been successful with floating clematis blooms, however I MUCH prefer to let the stems come out of the water. Sometimes I cut shorter stems when absolutely needed. A shorter bouquet is prettier than a few floated flowers, I think.
Suzy

I forgot to include this picture of a bouquet which was sent to me from Chalk Hill Clematis in California all the way to my address in Massachusetts ! It was beyond gorgeous !
{{gwi:626360}}