By John_a
I have a white (pot grown) and a Red Camellia shrubs
They bud nicely during the winter and start to flower in the spring. The buds turn from the green to the colour and before they open fully go brown and drop off.
they are sheltered from strong winds and have plenty of light.
3 Mar, 2015
Answers
It would help to know whereabouts you are in the world - UK (which bit) or elsewhere and where the plant is, other than in plenty of light.
It looks like frost damage, as per Bamboo's posting, and that would be the obvious answer at this time of year in most of the UK and given that we have had a few cold nights, you might want to give your plants a bit of late protection.
btw that pot doesn't look big enough for the amount of camellia visible.
4 Mar, 2015
Previous question
Two possibilities - the flowers are hit by the sun as soon as it comes up in the morning, before frost has had a chance to dissipate, or at least get sun on them whilst they are covered in frost. The second possibility is Camellia flower blight - there is no treatment for this fungal infection, but you should collect all fallen blooms as quickly as possible and dispose of them away from your garden.
The RHS has a page on Camellia flower blight if you want more information.
3 Mar, 2015