I have focused in on the 2-3 inch heads that are starting to form on my Primero purple cabbage plants. The outer set of leaves is probably 18 inches wide right now.
Purple cabbage tastes the same as green cabbage and can be used interchangeably in recipes. However you have to be aware that it will bleed and stain the other foods, like a beet does. Why grow purple cabbage organically? Because it makes the worms so easy to find!
Edit: Above I said that these were “Primero” cabbages. They are in fact Red Acres cabbages. I am growing both this year, and they look very similar.