Robin, I have very good success rate on the bench in the conservatory, not so much just pushed into the soil in the garden. Goodlife's advise was to root them into individual pots and keep them in the shade underneath the greenhouse bench and as cool as possible as well.
I can root them, but don't find it as easy as has been said. I planted one out a few days ago that was rooted nicely and 'something' ate it right down to stumps. Another couple of shoots that I pushed into the ground about a month ago looked fine at first, but the cold nights killed them. If you take several new shoots and root them different ways you should be successful.
Also do the propagating as soon as possible. My first attempt at Daubentons failed, because the plants were not big enough to get through winter. Goodlife had to bail me out again and I protected the kales over their first winter. Now they are as tough as old boots. Last year's cuttings just worked, pushed into the ground and sailed through winter, really not sure why it was so difficult to start with. If you take several cuttings and they all root, there will be takers, that's for sure. Good luck