It's starting to spread out. Don't know when to pick it or what to do for it.
My Cauliflower Has a Purple Tint to It
Certified GKH Gardening Expert
This was either caused by the weather (some cauliflowers grow slightly purple under cooler or unusually hot conditions) or you could have bought a purple cauliflower (if you did not mean too, it was probably mislabled). Either way, it will not harm you. They are just as edible. This article will help with harvesting your cauliflower: https://www.gardeningknowhow.com/edible/vegetables/cauliflower/harvest-cauliflower.htm