United Kingdom 
I have a spring/summer large purple clematis. Last spring it was very much disturbed. This year is has produced small white flowers together with outstanding large purple blooms. Is this unusual?
1 Jun, 2015
Previous question
No they often do this apparently. there are some that flower single early on then go onto flower fully double for the rest of the year. I suspect a cold spell disrupts the flower formation and in your case it was a s the pigment was due to be made by the plant.
1 Jun, 2015