Red cabbage

   

Here's one of the self-seeded offspring. A tenacious soul who decided to grow outside the bed with his roots horizontal under the bed edge. The path is part of the GH base so the roots can't go down!
I'm in awe of its will to live so have left it there as a reward.

Another option you could try is to use those side shoots as cuttings and root them. Take off the flower heads, put the shoots in water and wait for the roots. Pot them up and see what happens! I've done it with Primo cabbage and kale.