ornamental cabbage

Any advise on growing ornamental cabbage here in MI?

We moved here two summers ago from Alaska where the ornamental cabbage sometimes grows three feet across. I planted a few last summer and they only grew to about 9". Can anyone advise as to how to get some size out of these things here? I know that daylight has a lot to do with it - but surely that's not all there is to it.

Thanks in advance. Rhonda

I had bearutiful ones last yr from the seeds we got in a co-op here at daves
10 different kinds and they were big and beautiful- i started them in the GH and kept them there till they were good size and the ones in full sun grew HUGE and some are even coming back-weird as i thought they were annuals!

Thanks for the info Dori. I didn't have them in full sun last year - will try a new location this year. They're just too pretty to pass up so I just had to try again. We put in a new retaining wall and the site should be perfect for them.
Rhonda