"Dave Poole" wrote
I have a clematis florida sieboldii (the purple and white one like a
passion
flower). Anyhoo, the white petals are actually more greenish. Is that
normal, or is the plant lacking in something?

This is perfectly normal. The white 'petals' are really tepals -
modified bracts or leaves.

Dave, many thanks for your reply. I look forward to seeing the change to
white!

Regards,