I've had hit-and-miss experiences growing ornamental kale. Some years they do well, some years not. Colder temperatures are a must as they will bolt in warmer climes. They respond well to fertilizer although I confess I usually forget to fertilize them. They do not like extreme wet conditions and are especially vulnerable to freezing rain, which leaves them puny and limp. If freezing rain is predicted, cover the plants if you can until the danger has past.