Mine is doing the same thing. All of the potted ones are all green. Moved them into the full sun hoping it will help them to bolt, but I do not see any buds yet.

I did get one to bloom this year. It actually bloomed in Spring and again in late Summer. It grew in ground from a pack of wildflower seeds. There is a good chance it overwintered from seeds I planted last year, or maybe they were sewn in late winter.