the most common is low temp at the critical time of growth a late onset of spring or dry soil at start of the growth

so do not let the plants run short of water and choose cultivars that are listed as bolt resistance

Also cauliflowers need a very rich soil to produce a curd rather than going to seed. A lot of GoYers have had problems with brassicas going to seed this year.

We have harvested our cauli's while small to beat this problem. Though small they have been beautiful. We were told an invaluable tip was that when the cauli is about the size of a small apple, snap the leaves surrounding the cauli and fold them over the cauli to keep out the worms. It has certainly helped us and no worm problem at all

Good tip Bridie!