Anthocyanin is very sensitive to temperature and light. The colder
it is the more anthocyanin a flower produces. the more light there is,
the less anthocyanin there is in flower. In rainy overcast conditions
the anthocyanin is much enhanced.
These effects are more noticable in flowers where the anthocyanin is a
wash, as the extra anthocyanin in these cases can produce dramatic
effects. When the flower has a lot of anthocyanin as in blues and
purples, the changes in amount of anthocyanin does not produce a
difference because the base amount is so large that a small
difference is not noticable.
So colder weather and lack of sun during last few days before bloom
can produce a dramatic difference in amount of anthocyanin .
Keth Keppel commented to me. that with a lot of SDBs he never
understood why the anthocynin colurs descibed in descriptions never
seemed to be as described when they bloomed n his garden in
When he move to Oregon, suddenly all these SDBs now had
the colurs as described, with the increased anthocyanin with cooler
For some good examples of variations of this type, look at the Space
Age group, and look at the file photos of Thornbird, a flower with a
light anthocyanin wash. Very dramatic differences in many of the
photos, depending on climate wher grown, and amount of anthocyanin
produced in that climatic condititon.