I have just stated harvesting caulifowers but notice the larger ones have developed a purple tinge, the discolouration seems to be confined to the surface. some leaves also have a touch of purple, is this a disease?
Cauliflowers can take on a pink or purplish tinge when exposed to sunlight. A factor can be, especially on peaty ground, that they are short of phosphorus, which is the P in NPK fertilzers. You could try applying a general fertiliser or superphosphate, if you can get it, at 30g per square metre.